Email alert
RSS2005 Vol. 17, No. 05s
Recommend Articles
column
Display Method:
2005,
17.
Abstract:
An actively mode-locked Nd:YAG laser with an optimized resonator was demonstrated which can provide with large mode volume in the active material and high stability against thermal lensing fluctuations. By using a compact pump module which utilizes a radial array of close-coupled diode laser arrays for efficient direct side pumping of the Nd:YAG rod, as well as, a phase-lock loop circuit, 10 W continuous-wave mode-locked stable pulses were obtained.
An actively mode-locked Nd:YAG laser with an optimized resonator was demonstrated which can provide with large mode volume in the active material and high stability against thermal lensing fluctuations. By using a compact pump module which utilizes a radial array of close-coupled diode laser arrays for efficient direct side pumping of the Nd:YAG rod, as well as, a phase-lock loop circuit, 10 W continuous-wave mode-locked stable pulses were obtained.
2005,
17.
Abstract:
Simultaneous self-Q-switched and mode-locking was demonstrated in a diode-pumped Nd,Cr:YAG laser with an almost 100% modulation depth. The maximum average output power of 1.9 W was obtained at 1 064 nm with stability better than 1%. The corresponding Q-switched pulse had a repetition rate of 61 kHz and a pulse duration of 157 ns. The repetition rate of the mode locked pulse was 149 MHz.
Simultaneous self-Q-switched and mode-locking was demonstrated in a diode-pumped Nd,Cr:YAG laser with an almost 100% modulation depth. The maximum average output power of 1.9 W was obtained at 1 064 nm with stability better than 1%. The corresponding Q-switched pulse had a repetition rate of 61 kHz and a pulse duration of 157 ns. The repetition rate of the mode locked pulse was 149 MHz.
2005,
17.
Abstract:
The package structure and high efficiency cooling technique have been studied for high average power diode laser. The laser power of single CW DL bar reach 50 W, the life time reached 5 000 h, and the power of QCW DL bar reached 150 W at 10% duty cycle, 100 W at 25% duty cycle, the life time reached 5×109 pulse. The 25 bar stack DL arrays were made with module structure, it's laser power reached CW 1 kW and QCW 2.5 kW at 20% duty cycle.
The package structure and high efficiency cooling technique have been studied for high average power diode laser. The laser power of single CW DL bar reach 50 W, the life time reached 5 000 h, and the power of QCW DL bar reached 150 W at 10% duty cycle, 100 W at 25% duty cycle, the life time reached 5×109 pulse. The 25 bar stack DL arrays were made with module structure, it's laser power reached CW 1 kW and QCW 2.5 kW at 20% duty cycle.
2005,
17.
Abstract:
The upconversion luminescence of Yb3+-doped yttrium aluminum garnets under 940 nm excitation at room teperature was studied, and it was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. X-ray excited luminescence features of the crystal were also measured and the emission bands correspond to the transition from charge transfer state to the ground and excited state of Yb3+ ion. The emission spectra of Cr,Yb:YAG crystal were studied and the Cr4+ emission band was observe with its peak at 1.35 μm wavelength range from 1.2 to 1.6 μm. The probability of Cr4+ laser output was discussed.
The upconversion luminescence of Yb3+-doped yttrium aluminum garnets under 940 nm excitation at room teperature was studied, and it was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. X-ray excited luminescence features of the crystal were also measured and the emission bands correspond to the transition from charge transfer state to the ground and excited state of Yb3+ ion. The emission spectra of Cr,Yb:YAG crystal were studied and the Cr4+ emission band was observe with its peak at 1.35 μm wavelength range from 1.2 to 1.6 μm. The probability of Cr4+ laser output was discussed.
2005,
17.
Abstract:
The theory of beam shaping of laser diode array (LDA) is described and a beam-shaping system composed of two blazed grating arrays is presented. The system can theoretically transform the beam parameter product (BPP) of LDA into 5.7 mm·mrad in the fast axis and 8.9 mm·mrad in the slow axis. Experimental results indicate the BPP of the fast axis can be transformed into 12 mm·mrad and 9.5 mm·mrad for the slow axis after beam shaping. The beams can be coupled into the fiber of 200 μm diameter and numerical aperture of 0.22 after focused.
The theory of beam shaping of laser diode array (LDA) is described and a beam-shaping system composed of two blazed grating arrays is presented. The system can theoretically transform the beam parameter product (BPP) of LDA into 5.7 mm·mrad in the fast axis and 8.9 mm·mrad in the slow axis. Experimental results indicate the BPP of the fast axis can be transformed into 12 mm·mrad and 9.5 mm·mrad for the slow axis after beam shaping. The beams can be coupled into the fiber of 200 μm diameter and numerical aperture of 0.22 after focused.
2005,
17.
Abstract:
Thermal lens and stress induced birefringence are two key effects that must be considered in the design and optimization of high-power DPL. This paper discusses the general way of calculating the thermal lens by finite-difference beam propagation method and that of calculating the stress induced birefringence using the elasto-optical coefficients of the material. The effects of the thermal lens and the stress induced birefringence on beams were calculated for a 6 cm Nd:YAG rod. The results show that the wavefront amplitude in the center of the rod increases about 6% after one pass, and the wavefront phase difference between the center and the edge of the rod reaches nearly 20 wavelengths; meanwhile, about 30% power losses due to birefringence．
Thermal lens and stress induced birefringence are two key effects that must be considered in the design and optimization of high-power DPL. This paper discusses the general way of calculating the thermal lens by finite-difference beam propagation method and that of calculating the stress induced birefringence using the elasto-optical coefficients of the material. The effects of the thermal lens and the stress induced birefringence on beams were calculated for a 6 cm Nd:YAG rod. The results show that the wavefront amplitude in the center of the rod increases about 6% after one pass, and the wavefront phase difference between the center and the edge of the rod reaches nearly 20 wavelengths; meanwhile, about 30% power losses due to birefringence．
2005,
17.
Abstract:
This paper theoretically and experimentally investigated the elements which influence the gain distribution of laser medium. A high energy storage laser module was manufactured. In this module an 8 mm diameter Nd:YAG rod which was 120 mm long was pumped by twelve diodes-arrays (the peak pump-power was 12 kW). Each array consisted of twelve diodes. Numerical calculation was done to optimize the coupling structure. In order to satisfy the condition of reducing heat, a microchannel cooling structure was adopted. The experiment result shows that the gain coefficient of this module is 0.186/cm and the storage power is about 700 mJ per pulse．
This paper theoretically and experimentally investigated the elements which influence the gain distribution of laser medium. A high energy storage laser module was manufactured. In this module an 8 mm diameter Nd:YAG rod which was 120 mm long was pumped by twelve diodes-arrays (the peak pump-power was 12 kW). Each array consisted of twelve diodes. Numerical calculation was done to optimize the coupling structure. In order to satisfy the condition of reducing heat, a microchannel cooling structure was adopted. The experiment result shows that the gain coefficient of this module is 0.186/cm and the storage power is about 700 mJ per pulse．
2005,
17.
Abstract:
An all solid state laser was built, which is composed of a directional prism resonator, half-circular LD array to pump two Nd:YAG rods, Cr4+:YAG passive Q switched, and heat-conduct structure etc. It is a practical engineering instrument with high stability and high beam quality. Light travels back and forth symmetrically in cavity, that lets the gain distribution become even, and depresses the high order mode. At the same time, the attribution of the directional prism including the phase-conjugate and self-collimation can compensate the phase aberration, the wedge-shaped effect and double-refraction effect by heat. It ensures the heat stability in large repetition range. Laser operates with 53 ampere, 10 Hz repetition rate at room temperature. Experimental results are as follows: laser ou
An all solid state laser was built, which is composed of a directional prism resonator, half-circular LD array to pump two Nd:YAG rods, Cr4+:YAG passive Q switched, and heat-conduct structure etc. It is a practical engineering instrument with high stability and high beam quality. Light travels back and forth symmetrically in cavity, that lets the gain distribution become even, and depresses the high order mode. At the same time, the attribution of the directional prism including the phase-conjugate and self-collimation can compensate the phase aberration, the wedge-shaped effect and double-refraction effect by heat. It ensures the heat stability in large repetition range. Laser operates with 53 ampere, 10 Hz repetition rate at room temperature. Experimental results are as follows: laser ou
2005,
17.
Abstract:
Structural parameter of micro-channel heatsink is optimized through numerical calculation. Heat resistances of 4 different structural micro-channel heatsinks are measured by experiment. In order to take advantage of copper's high thermal conductivity, and W-Cu alloy's high hardness, micro-channel heatsink module is made by compound Cu-WCu layers. With an exterior size of 25.0 mm×12.0 mm×1.5 mm and heat resistance of 0.4～0.8 K/W, the optimized micro-channel heatsink module can match the need of thermal spread for high power diode laser with pulse power 120 W(duty cycle 20%) or continual power 50W, and can be used to package two-dimension high cycle duty or continual diode laser.
Structural parameter of micro-channel heatsink is optimized through numerical calculation. Heat resistances of 4 different structural micro-channel heatsinks are measured by experiment. In order to take advantage of copper's high thermal conductivity, and W-Cu alloy's high hardness, micro-channel heatsink module is made by compound Cu-WCu layers. With an exterior size of 25.0 mm×12.0 mm×1.5 mm and heat resistance of 0.4～0.8 K/W, the optimized micro-channel heatsink module can match the need of thermal spread for high power diode laser with pulse power 120 W(duty cycle 20%) or continual power 50W, and can be used to package two-dimension high cycle duty or continual diode laser.
2005,
17.
Abstract:
Using statistics analysis method, diode laser failure states were classified and the causes of these diode laser failures were analyzed in every packaging process. The result of the statistics analysis shows that the main causes of these failures are solder void, pn short circuit and facet damage. The packaging techniques were optimized and ameliorated and the production rate is improved from 77% to 85%．
Using statistics analysis method, diode laser failure states were classified and the causes of these diode laser failures were analyzed in every packaging process. The result of the statistics analysis shows that the main causes of these failures are solder void, pn short circuit and facet damage. The packaging techniques were optimized and ameliorated and the production rate is improved from 77% to 85%．
2005,
17.
Abstract:
Microchannel heat sinks are minute channels fabricated onto the back of the thin silicon chip substrate with hydraulic diameter ranging from 10 to 103 μm. Microchannels have the advantage of large surface area to volume ratio, low thermal resistances and low flux, so they are thought to be an effective solution in dissipating thermal. One typical application is the cooling of the laser diode arrays. Because flow and heat transfer in microchannel are different from those in macro one, further research is necessary. An FEA (finite element analysis) model of a flat plate microchannel is set up in this paper using commercial software CoventorWareTM to investigate the localized flow and heat transfer in a single microchannel, computation results are also presented and analyzed. Microchannel is
Microchannel heat sinks are minute channels fabricated onto the back of the thin silicon chip substrate with hydraulic diameter ranging from 10 to 103 μm. Microchannels have the advantage of large surface area to volume ratio, low thermal resistances and low flux, so they are thought to be an effective solution in dissipating thermal. One typical application is the cooling of the laser diode arrays. Because flow and heat transfer in microchannel are different from those in macro one, further research is necessary. An FEA (finite element analysis) model of a flat plate microchannel is set up in this paper using commercial software CoventorWareTM to investigate the localized flow and heat transfer in a single microchannel, computation results are also presented and analyzed. Microchannel is
2005,
17.
Abstract:
Great nonlinear coefficients of quasi-phase-matching crystals may be used in optical parametric chirped-pulse amplification (OPCPA) system. This is particularly true for the applications that require high repetition rates and small pump energies. The numerical simulations show that a saturatiom amplificatiom gain of above 6.2×106 and over 25% pump-to-signal conversion efficiency can be obtained with a periodically poled crystal in the first stage of the optical parametric amplification. A high repetition rate and sub-terawatt OPCPA laser system with diode-laser pumping was discussed．
Great nonlinear coefficients of quasi-phase-matching crystals may be used in optical parametric chirped-pulse amplification (OPCPA) system. This is particularly true for the applications that require high repetition rates and small pump energies. The numerical simulations show that a saturatiom amplificatiom gain of above 6.2×106 and over 25% pump-to-signal conversion efficiency can be obtained with a periodically poled crystal in the first stage of the optical parametric amplification. A high repetition rate and sub-terawatt OPCPA laser system with diode-laser pumping was discussed．
2005,
17.
Abstract:
Phase-locking of a diode laser array was achieved in a simple external cavity consisting of a fast axis collimating lens and a high-reflection coated external mirror. When the cavity length is a few centimeter, the far field pattern has 3 lobes, and the divergence of each lobe is about 10 mrad and the contrast of the far field pattern is about 50%. The energy in the side-lobes can be suppressed by blocking the output of some emitters.
Phase-locking of a diode laser array was achieved in a simple external cavity consisting of a fast axis collimating lens and a high-reflection coated external mirror. When the cavity length is a few centimeter, the far field pattern has 3 lobes, and the divergence of each lobe is about 10 mrad and the contrast of the far field pattern is about 50%. The energy in the side-lobes can be suppressed by blocking the output of some emitters.
2005,
17.
Abstract:
Using a high reflectivity mirror as the external cavity of a 19-unit diode laser array(LDA), the optical beam from the LDA can be coupled into itself by adjusting the distance and tilting angle of the external mirror. The bandwidth of the LDA was narrowed down and its threshold current was reduced. With the external feedback, the spectra of the LDA at different drive currents were narrowed to about the tenth of that without feedback, the threshold current decreased from 7 A to 5.5 A, and the output power increased by two times.
Using a high reflectivity mirror as the external cavity of a 19-unit diode laser array(LDA), the optical beam from the LDA can be coupled into itself by adjusting the distance and tilting angle of the external mirror. The bandwidth of the LDA was narrowed down and its threshold current was reduced. With the external feedback, the spectra of the LDA at different drive currents were narrowed to about the tenth of that without feedback, the threshold current decreased from 7 A to 5.5 A, and the output power increased by two times.
2005,
17.
Abstract:
Hollow lens duct is a good choice for the coupling system of the large-aperture high power diode arrays. With numerical analysis of three-dimension ray tracing, a computer simulation program was developed for end-pumped LD arrays coupling system. Based on the result of simulation, a coupling system for a large-aperture(>100 cm2) high-power(48 kW) LD arrays was built, which has a hollow lens duct and a homogenizer. The pumping radiations was coupled into a laser crystal of only about 4 cm2, with coupling efficiency beyond 70% and perfect pumping-uniformity in the gain material.
Hollow lens duct is a good choice for the coupling system of the large-aperture high power diode arrays. With numerical analysis of three-dimension ray tracing, a computer simulation program was developed for end-pumped LD arrays coupling system. Based on the result of simulation, a coupling system for a large-aperture(>100 cm2) high-power(48 kW) LD arrays was built, which has a hollow lens duct and a homogenizer. The pumping radiations was coupled into a laser crystal of only about 4 cm2, with coupling efficiency beyond 70% and perfect pumping-uniformity in the gain material.
2005,
17.
Abstract:
The article mainly discusses the design of pump coupling system that is one of the key technology of disk laser. In the optical system, we applied three fast and slow axis collimation cylinder lenses and one cylinder HR mirror. The fast and slow collimation cylinder lenses collimate 220-bar diode lasers stack's pump light. The cylinder HR mirror insure the pump laser 4 times pass through the laser medium. The beam size at the pumped area is 23 mm×27 mm. The coupling efficiency is 85%. The pumping light beam tested by CCD camera is nearly symmetric.
The article mainly discusses the design of pump coupling system that is one of the key technology of disk laser. In the optical system, we applied three fast and slow axis collimation cylinder lenses and one cylinder HR mirror. The fast and slow collimation cylinder lenses collimate 220-bar diode lasers stack's pump light. The cylinder HR mirror insure the pump laser 4 times pass through the laser medium. The beam size at the pumped area is 23 mm×27 mm. The coupling efficiency is 85%. The pumping light beam tested by CCD camera is nearly symmetric.
2005,
17.
Abstract:
This paper presents the numerical simulation of the Nd:YAG disk as the high power laser medium. The upper surface of the disk is pumped by the diode array, and the other side is cooled by copper heat sink. Temperature and stress are simulated for the disk partly pumped by an area of 7.5 mm×6.2 mm as well as pumped from its whole surface .The results show that with the same pumping power intensity, environment temperature and cooling, the overall stress of the disk fully pumped is smaller than that of the partly pumped disk. As the former is mainly caused by the difference of thermal expansion between the disk and the copper heatsink,it reduces when the compound diamond is used as a medium. While the latter, which is mainly caused by the temperature difference between the pumped and non-pu
This paper presents the numerical simulation of the Nd:YAG disk as the high power laser medium. The upper surface of the disk is pumped by the diode array, and the other side is cooled by copper heat sink. Temperature and stress are simulated for the disk partly pumped by an area of 7.5 mm×6.2 mm as well as pumped from its whole surface .The results show that with the same pumping power intensity, environment temperature and cooling, the overall stress of the disk fully pumped is smaller than that of the partly pumped disk. As the former is mainly caused by the difference of thermal expansion between the disk and the copper heatsink,it reduces when the compound diamond is used as a medium. While the latter, which is mainly caused by the temperature difference between the pumped and non-pu
2005,
17.
Abstract:
Thermal effects such as the thermally induced lens and thermally induced birefringence of the laser rod pumped by high power LD in laser amplifier and their compensations were discussed. Minus lenses can make good compensation for the thermally induced lens of the laser rod. The depolarization loss caused by the birefringence is reduced with a 90°quartz rotator and imaging relay optical system between two similar laser modules. Both of the output power and the efficiency of laser are improved in experiment.
Thermal effects such as the thermally induced lens and thermally induced birefringence of the laser rod pumped by high power LD in laser amplifier and their compensations were discussed. Minus lenses can make good compensation for the thermally induced lens of the laser rod. The depolarization loss caused by the birefringence is reduced with a 90°quartz rotator and imaging relay optical system between two similar laser modules. Both of the output power and the efficiency of laser are improved in experiment.
2005,
17.
Abstract:
A V-shaped Silicon microchannel cooler has an advantage of packaging compact laser diode arrays due to its high cooling power and specific structure. The structure and fabrication process of the V-shaped silicon microchannel cooler are reported. The cooler contains a silicon wafer and a glass manifold. The silicon wafer contains V-shaped grooves and microchannels of 30 μm wide which are etched by anisotropic etching after being photolithed. The whole cooler is formed by bonding silicon wafer to glass manifold. Some coolers were fabricated and tested. The results show that it has a thermal impedance of 0.051 ℃·cm2/W for the single groove facet that match the results of numerical simulation. The cooler meets the requirement for packaging laser diode arrays with a peak power density up t
A V-shaped Silicon microchannel cooler has an advantage of packaging compact laser diode arrays due to its high cooling power and specific structure. The structure and fabrication process of the V-shaped silicon microchannel cooler are reported. The cooler contains a silicon wafer and a glass manifold. The silicon wafer contains V-shaped grooves and microchannels of 30 μm wide which are etched by anisotropic etching after being photolithed. The whole cooler is formed by bonding silicon wafer to glass manifold. Some coolers were fabricated and tested. The results show that it has a thermal impedance of 0.051 ℃·cm2/W for the single groove facet that match the results of numerical simulation. The cooler meets the requirement for packaging laser diode arrays with a peak power density up t
2005,
17.
Abstract:
In order to get ultra-short intensity laser pulses, it is necessary to amplify the laser pulses from nJ level to mJ level. The regenerativeamplifier is the best way to get high-energy laser pulse. It can amplify the seed from nJ level to mJ level quickly. And the output laser has a good spatial mode. A Ti:sapphire regenerative amplifier was designed in this paper.Otherwise, in order to make the output laser stable, a 1 kHz 527 nm green laser was used as the pump laser in the experiment. Using such a Ti:sapphire regenerative amplifier, a 12 nJ seed which was generated from a self mode-locking Ti:sapphire oscillator was amplified to energy of 2.3 mJ in a pulse at 1 kHz. The spectrum of the amplifier was also measured. When the 40 nm seed was injected into the cavity, a laser output of about
In order to get ultra-short intensity laser pulses, it is necessary to amplify the laser pulses from nJ level to mJ level. The regenerativeamplifier is the best way to get high-energy laser pulse. It can amplify the seed from nJ level to mJ level quickly. And the output laser has a good spatial mode. A Ti:sapphire regenerative amplifier was designed in this paper.Otherwise, in order to make the output laser stable, a 1 kHz 527 nm green laser was used as the pump laser in the experiment. Using such a Ti:sapphire regenerative amplifier, a 12 nJ seed which was generated from a self mode-locking Ti:sapphire oscillator was amplified to energy of 2.3 mJ in a pulse at 1 kHz. The spectrum of the amplifier was also measured. When the 40 nm seed was injected into the cavity, a laser output of about
2005,
17.
Abstract:
As the representation of the third generation laser device high power double cladd fiber laser is applicatted in industry process and laser beam weapons. The developments of Yb3+ doped fiber lasers is introduced in this paper. The relationship between pumped threshold value and output power is analyzed in theory. One experiment device on high power LD pumped Yb3+ doped double cladding fiber laser is designed.The key technologies in the experiment are concluded. The obtained result can be a reference for developing the proper laser equipment.
As the representation of the third generation laser device high power double cladd fiber laser is applicatted in industry process and laser beam weapons. The developments of Yb3+ doped fiber lasers is introduced in this paper. The relationship between pumped threshold value and output power is analyzed in theory. One experiment device on high power LD pumped Yb3+ doped double cladding fiber laser is designed.The key technologies in the experiment are concluded. The obtained result can be a reference for developing the proper laser equipment.
2005,
17.
Abstract:
As a high power laser which has some important application background, the selection of solid-state laser’s parameters such as wavelength, beam aperture, power, and beam quality has been analyzed, and the influencing factors such as the atmospheric optical characteristics, the effects of laser beams propagation in the atmosphere, and the mechanism and efficiency of laser beam coupling with targets has been investigated. The related results show that the general efficiency of 100 kW solid-state lasers corresponds to DF lasers which have two to three times average out power, thus the high average out power solid-state laser is demonstrated as a laser of some potential advantages and favorable prosperity.
As a high power laser which has some important application background, the selection of solid-state laser’s parameters such as wavelength, beam aperture, power, and beam quality has been analyzed, and the influencing factors such as the atmospheric optical characteristics, the effects of laser beams propagation in the atmosphere, and the mechanism and efficiency of laser beam coupling with targets has been investigated. The related results show that the general efficiency of 100 kW solid-state lasers corresponds to DF lasers which have two to three times average out power, thus the high average out power solid-state laser is demonstrated as a laser of some potential advantages and favorable prosperity.
2005,
17.
Abstract:
High average power diode pumped laser (HAP-DPL) is a developing concept and research field. Its every progress depends on the technological innovation. Different approaches of the thermal management lead to the different type of HAP-DPL even beyond the all-solid-state laser concept. HAP-DPL has the good application perspective. The five application directions are given. Meanwhile the paper indicates that there are some restraints such as energy, heat controll for HAP-DPL development.
High average power diode pumped laser (HAP-DPL) is a developing concept and research field. Its every progress depends on the technological innovation. Different approaches of the thermal management lead to the different type of HAP-DPL even beyond the all-solid-state laser concept. HAP-DPL has the good application perspective. The five application directions are given. Meanwhile the paper indicates that there are some restraints such as energy, heat controll for HAP-DPL development.
2005,
17.
Abstract:
An LD pumped high power Nd:GdVO4 laser was reported. A continuous and pulse output of 1 064 nm was obtained. In the experiment of continuous output, when the pumped power was 20.2 W, an output power of 11.5 W with a maximum optical conversion efficiency of 55.0% and a slope efficiency of 59.1% was obtained. In the acousto-optic Q-switch experiment, when the repetition is 10 kHz, a pulse width of 6.5 ns, a peak power of 52.3 kW and an energy of 340 μJ were obtained. As the repetition was 30 kHz and the minimum pulse width was 14.5 ns, the average output power was 5.18 W.
An LD pumped high power Nd:GdVO4 laser was reported. A continuous and pulse output of 1 064 nm was obtained. In the experiment of continuous output, when the pumped power was 20.2 W, an output power of 11.5 W with a maximum optical conversion efficiency of 55.0% and a slope efficiency of 59.1% was obtained. In the acousto-optic Q-switch experiment, when the repetition is 10 kHz, a pulse width of 6.5 ns, a peak power of 52.3 kW and an energy of 340 μJ were obtained. As the repetition was 30 kHz and the minimum pulse width was 14.5 ns, the average output power was 5.18 W.
2005,
17.
Abstract:
An LD side-pumped A-O Q-switched intracavity frequency doubled Nd: YAG laser was studied. A folded resonator with a single pump head was experimentally studied and theoretically analyzed. Under the condition of a total pump power of 800 W and a repetition rate of 10 kHz, a beam with a green output power of 112 W, a pulse width of 80 ns and a divergence angle of 6 mrad was achieved when V-shaped resonator was employed. When Z-shaped resonator was employed, a beam with output power of 120 W, pulse width of 95 ns and divergence angle of 4 mrad was obtianed．
An LD side-pumped A-O Q-switched intracavity frequency doubled Nd: YAG laser was studied. A folded resonator with a single pump head was experimentally studied and theoretically analyzed. Under the condition of a total pump power of 800 W and a repetition rate of 10 kHz, a beam with a green output power of 112 W, a pulse width of 80 ns and a divergence angle of 6 mrad was achieved when V-shaped resonator was employed. When Z-shaped resonator was employed, a beam with output power of 120 W, pulse width of 95 ns and divergence angle of 4 mrad was obtianed．
2005,
17.
Abstract:
The theory of solid state Yb:YAG thin disk laser is introduced and it is compared with traditional rod Nd:YAG lasers. The powerful function of VersaDisk laser as dual wavelength output, wavelength tuning ability and single frequency are illustrated. Its scientific applications as high-resolution spectroscopy in the NIR, Bose-Einstein condensates and laser tweezers, high CW power Ti:sapphire and dye laser pumping are introduced．
The theory of solid state Yb:YAG thin disk laser is introduced and it is compared with traditional rod Nd:YAG lasers. The powerful function of VersaDisk laser as dual wavelength output, wavelength tuning ability and single frequency are illustrated. Its scientific applications as high-resolution spectroscopy in the NIR, Bose-Einstein condensates and laser tweezers, high CW power Ti:sapphire and dye laser pumping are introduced．
2005,
17.
Abstract:
Thermal effects present a major challenge to scaling of solid-state laser to high-average power. When using a thin laser crystal disc with a nearly flat top pump profile, the heat flux can be considered to be one-dimensional. This results in a homogeneous temperature and stress profile within the laser medium leading to dramatically reduce the thermal effects. Some factors that may affect the homogeneous temperature profile are analyzed, such as the cooling dimension and the ratio of the pump area to the thickness of the disc. More than 120 W of an average output power is obtained with a 336 W average pump power by using a good design.
Thermal effects present a major challenge to scaling of solid-state laser to high-average power. When using a thin laser crystal disc with a nearly flat top pump profile, the heat flux can be considered to be one-dimensional. This results in a homogeneous temperature and stress profile within the laser medium leading to dramatically reduce the thermal effects. Some factors that may affect the homogeneous temperature profile are analyzed, such as the cooling dimension and the ratio of the pump area to the thickness of the disc. More than 120 W of an average output power is obtained with a 336 W average pump power by using a good design.
2005,
17.
Abstract:
An LD-pumped Nd:YAG laser that generates simultaneous laser action at the wavelengths 1 064 nm and 946 nm by optimizing film design is presented. An optimized CW 593.5 nm yellow laser at room temperature was obtained for the first time. Using type-I critical phase-matching LBO crystal, 500.8 nm laser was obtained by 1 064 nm and 946 nm intracavity sum-frequency mixing for the first time. The maximum laser output power of 20 mW was obtained when an incident pump laser of 14 W was used. The optical-to-optical conversion was up to 1.4% and the power instability in 24 h was better than ±3%.
An LD-pumped Nd:YAG laser that generates simultaneous laser action at the wavelengths 1 064 nm and 946 nm by optimizing film design is presented. An optimized CW 593.5 nm yellow laser at room temperature was obtained for the first time. Using type-I critical phase-matching LBO crystal, 500.8 nm laser was obtained by 1 064 nm and 946 nm intracavity sum-frequency mixing for the first time. The maximum laser output power of 20 mW was obtained when an incident pump laser of 14 W was used. The optical-to-optical conversion was up to 1.4% and the power instability in 24 h was better than ±3%.
2005,
17.
Abstract:
A diode laser pumped Q-switched double-pass MOPA system operated on 400 Hz repetition rate and 15 ns pulse width has been investigated in this paper. The laser with a beam expanded mirror and a beam isolated equipment is amplified by two 6.5 kW diode laser pumped modules, each has 81 diode lasers. Two modules pumping Nd:YAG rod is used. Compensation of thermal birefringence is achieved by inserting a 90°crystal quartz rotator and using an imaging optical system between the two module. Besides, two appropriate concave lenses are placed on both sides of each pumped module for thermal lensing compensation. Accordingly, approximate apparel beam can be obtained through laser rods. The laser system developed can output 400 mJ energ with an optical-optical efficiency of 12.3% and beam quality of
A diode laser pumped Q-switched double-pass MOPA system operated on 400 Hz repetition rate and 15 ns pulse width has been investigated in this paper. The laser with a beam expanded mirror and a beam isolated equipment is amplified by two 6.5 kW diode laser pumped modules, each has 81 diode lasers. Two modules pumping Nd:YAG rod is used. Compensation of thermal birefringence is achieved by inserting a 90°crystal quartz rotator and using an imaging optical system between the two module. Besides, two appropriate concave lenses are placed on both sides of each pumped module for thermal lensing compensation. Accordingly, approximate apparel beam can be obtained through laser rods. The laser system developed can output 400 mJ energ with an optical-optical efficiency of 12.3% and beam quality of
2005,
17.
Abstract:
The power conditioning system for Xe-flash lamps pumped kW average power output solid state heat capacity laser (SSHCL) is described. It includes high power high voltage constant-current-charging system, capacitors bank, discharge control system, power supply of preignition for Xe-flash lamps, general control and diagnostic system. The practical application shows that the power conditioning system meets the design demands to operate at 7.5 kJ/pulse at a 10 Hz pulse repetition frequency, and runs well.
The power conditioning system for Xe-flash lamps pumped kW average power output solid state heat capacity laser (SSHCL) is described. It includes high power high voltage constant-current-charging system, capacitors bank, discharge control system, power supply of preignition for Xe-flash lamps, general control and diagnostic system. The practical application shows that the power conditioning system meets the design demands to operate at 7.5 kJ/pulse at a 10 Hz pulse repetition frequency, and runs well.
2005,
17.
Abstract:
A LDA side-pumped high-gain amplifier system with a dual-pass geometry is reported in this paper. According to the requirement of ICF driver, four ring-LD side-pumping Nd3+:YLF amplifiers are used in this system. More than 106 gain are achieved when input pulse energy is several nJ at 1 053 nm, the output pulse has good energy stability and perfect near-field distribution.
A LDA side-pumped high-gain amplifier system with a dual-pass geometry is reported in this paper. According to the requirement of ICF driver, four ring-LD side-pumping Nd3+:YLF amplifiers are used in this system. More than 106 gain are achieved when input pulse energy is several nJ at 1 053 nm, the output pulse has good energy stability and perfect near-field distribution.
2005,
17.
Abstract:
CW and Q-switched operation of Tm, Ho:GdVO4 laser is reported in this paper. The Tm,Ho:GdVO4 crystal is cooled by liquid nitrogen and end-pumped by a laser diode of 793nm. Output power of 4.0 W and optical-to-optical efficiency of 26% is achieved at CW mode. With acousto-optically Q-switched operation, an average power 3.9 W of at a pulse-repetition rate of 10 kHz with pulse duration of 50ns is obtained. The pulse width is tunable from 23 ns to 50 ns by changing rf(radio frequency) off-time of AO Q-switch. At a pulse-repetition rate of 10 kHz, 0.39 mJ of pulse energy, and 7.8 kW of peak power were measured
CW and Q-switched operation of Tm, Ho:GdVO4 laser is reported in this paper. The Tm,Ho:GdVO4 crystal is cooled by liquid nitrogen and end-pumped by a laser diode of 793nm. Output power of 4.0 W and optical-to-optical efficiency of 26% is achieved at CW mode. With acousto-optically Q-switched operation, an average power 3.9 W of at a pulse-repetition rate of 10 kHz with pulse duration of 50ns is obtained. The pulse width is tunable from 23 ns to 50 ns by changing rf(radio frequency) off-time of AO Q-switch. At a pulse-repetition rate of 10 kHz, 0.39 mJ of pulse energy, and 7.8 kW of peak power were measured
2005,
17.
Abstract:
The shift coefficients of the central wavelength of diode laser under different cooling water temperature and operating current were measured. The gain distrubution in the Nd:YAG rod was theoretically studied using ray tracing program. Without the help of collimating lens, two kinds of diode-side-pumped modules were designed with different output power levels of 170 W and 800 W. The maximum optical to optical conversion efficiency is 37%.
The shift coefficients of the central wavelength of diode laser under different cooling water temperature and operating current were measured. The gain distrubution in the Nd:YAG rod was theoretically studied using ray tracing program. Without the help of collimating lens, two kinds of diode-side-pumped modules were designed with different output power levels of 170 W and 800 W. The maximum optical to optical conversion efficiency is 37%.
2005,
17.
Abstract:
The development and current status of solid-state heat capacity lasers are described. The basic principle of a high power solid-state heat capacity laser is introduced. The experimental results of a diode-pumped Nd:YAG heat capacity disk laser are presented. Temperature profile in the gain medium is obtained. An interferogram of the gain medium is described. Fluorescence profile in the gain medium is described. Result indicates such a gain medium has little effect on the wavefront aberration of the beam. An average power of 47.5 W and an optical efficiency of 17% are obtained．
The development and current status of solid-state heat capacity lasers are described. The basic principle of a high power solid-state heat capacity laser is introduced. The experimental results of a diode-pumped Nd:YAG heat capacity disk laser are presented. Temperature profile in the gain medium is obtained. An interferogram of the gain medium is described. Fluorescence profile in the gain medium is described. Result indicates such a gain medium has little effect on the wavefront aberration of the beam. An average power of 47.5 W and an optical efficiency of 17% are obtained．
2005,
17.
Abstract:
Solid-state lasers and compact power supplies have been developed much well in recent years, and this makes it a possible aim that solid-state lasers powered by electricity will be applied in the near future. It is necessary to optimize the performance of a laser system design and to evaluate performance of the lasers system before its manufacture in order to maximize performance-cost ratio owing to its complexity and high expenses in manufacture. The laser wavelength should lie the “atmospheric window” and minimum attenuation of laser energy. The consideration in systems design mostly is limitation in physical optical effect and addition of adaptive optics system which could compensate for aberration induced by atmospheric effects. The atmospheric propagation and compensation code could
Solid-state lasers and compact power supplies have been developed much well in recent years, and this makes it a possible aim that solid-state lasers powered by electricity will be applied in the near future. It is necessary to optimize the performance of a laser system design and to evaluate performance of the lasers system before its manufacture in order to maximize performance-cost ratio owing to its complexity and high expenses in manufacture. The laser wavelength should lie the “atmospheric window” and minimum attenuation of laser energy. The consideration in systems design mostly is limitation in physical optical effect and addition of adaptive optics system which could compensate for aberration induced by atmospheric effects. The atmospheric propagation and compensation code could
2005,
17.
Abstract:
In a double-pass amplifier system, a laser pulse width(FWHM) of l6.9 ns and more than 216 mJ was obtained in the case of 10 Hz repetition frequency. Furthermore, 203.4 mJ per pulse was achieved where the repetition rate is up to 400 Hz. The beam quality factor is no more than 5 in the case and self-oscillating was successfully eliminated in experiments. But the distribution of laser section is asymmetric, and the reason was theoretically analyzed. HR mirror replaced by phase conjugated mirror and ocillating output mirror by sup-Guass mirror can improve the beam quality.
In a double-pass amplifier system, a laser pulse width(FWHM) of l6.9 ns and more than 216 mJ was obtained in the case of 10 Hz repetition frequency. Furthermore, 203.4 mJ per pulse was achieved where the repetition rate is up to 400 Hz. The beam quality factor is no more than 5 in the case and self-oscillating was successfully eliminated in experiments. But the distribution of laser section is asymmetric, and the reason was theoretically analyzed. HR mirror replaced by phase conjugated mirror and ocillating output mirror by sup-Guass mirror can improve the beam quality.
2005,
17.
Abstract:
The heat- capacity operation of a solid state laser is a novel method by which a high quality beam and high average power can be generated. This paper describes a diodes- pumped solid state heat capacity laser that produces average power of 300 W and a running duration of 5 s. In order to get a uniform gain distribution and acquire a fine thermal distribution to reduce the stress of laser material and to lengthen the time of output, numerical simulation was done to meet the operation conditions of laser . The experiment results show that the output power is up 300 W, the optical- optical efficiency is above 25%．
The heat- capacity operation of a solid state laser is a novel method by which a high quality beam and high average power can be generated. This paper describes a diodes- pumped solid state heat capacity laser that produces average power of 300 W and a running duration of 5 s. In order to get a uniform gain distribution and acquire a fine thermal distribution to reduce the stress of laser material and to lengthen the time of output, numerical simulation was done to meet the operation conditions of laser . The experiment results show that the output power is up 300 W, the optical- optical efficiency is above 25%．
2005,
17.
Abstract:
Tm1－xGdxAl3(BO3)4 crystals were grown from the K2Mo3O10-B2O3 flux by the top-seeded solution growth (TSSG) method. The TmAl3(BO3)4 crystal structure was measured. Tm3＋:GAB was cut into samples in c-axis and polarized absorption and emission spectra were measured. Based on the Judd-Ofelt theory, the optical parameters were calculated, such as intensity parameters, oscillator strengths, radiative transition, probabilities, radiative lifetime as well as the branching．
Tm1－xGdxAl3(BO3)4 crystals were grown from the K2Mo3O10-B2O3 flux by the top-seeded solution growth (TSSG) method. The TmAl3(BO3)4 crystal structure was measured. Tm3＋:GAB was cut into samples in c-axis and polarized absorption and emission spectra were measured. Based on the Judd-Ofelt theory, the optical parameters were calculated, such as intensity parameters, oscillator strengths, radiative transition, probabilities, radiative lifetime as well as the branching．
2005,
17.
Abstract:
Using an electron beam evaporation technique.ZrO2 thin films were deposited on three kinds of Lithium triborate (LiB305 or LBO) substrates with three different crystalline orientations. The influences of LBO structure on the microstructure and optical properties of ZrO2 thin films were studied by spectrophotometer and X-ray diffraction. The results indicate that the substrate structure has an obvious effect on the microstructure and optical property of the film, namely, the ZrO2 thin film deposited on the X-LBO, Y-LBO and Z-LBO oriented along m(－212), m(021) and o(130) directions. It is also found that the ZrO2 thin film with m(021) has the highest refractive index and the least lattice misfit．
Using an electron beam evaporation technique.ZrO2 thin films were deposited on three kinds of Lithium triborate (LiB305 or LBO) substrates with three different crystalline orientations. The influences of LBO structure on the microstructure and optical properties of ZrO2 thin films were studied by spectrophotometer and X-ray diffraction. The results indicate that the substrate structure has an obvious effect on the microstructure and optical property of the film, namely, the ZrO2 thin film deposited on the X-LBO, Y-LBO and Z-LBO oriented along m(－212), m(021) and o(130) directions. It is also found that the ZrO2 thin film with m(021) has the highest refractive index and the least lattice misfit．
2005,
17.
Abstract:
An LD-end-pumped Nd:YVO4 crystal 593 nm yellow laser by intracavity sum-frequency mixing (SFM) is reported. With one plane-curved cavity dual-wavelength operation, 1 064 nm and 1 342 nm, is realized. By LBO Intracavity SFM 593 nm laser is attained. With 1.4 W pump power 70 mW output power at 593 nm was observed. The far field divergence angle of 593 nm is less than 1 mrad and the ellipticity of the output beam is 0.999. Low-noise characteristic has been proved at the same time. The experiment show that this is the useful method to obtain solid state yellow laser with diffraction limit.
An LD-end-pumped Nd:YVO4 crystal 593 nm yellow laser by intracavity sum-frequency mixing (SFM) is reported. With one plane-curved cavity dual-wavelength operation, 1 064 nm and 1 342 nm, is realized. By LBO Intracavity SFM 593 nm laser is attained. With 1.4 W pump power 70 mW output power at 593 nm was observed. The far field divergence angle of 593 nm is less than 1 mrad and the ellipticity of the output beam is 0.999. Low-noise characteristic has been proved at the same time. The experiment show that this is the useful method to obtain solid state yellow laser with diffraction limit.
2005,
17.
Abstract:
The strongest transition of the Nd:YAG occurs at 1 064 nm, which exhibits a fluorescence linewidth of 4～6 cm-1, the Nd:YAG laser shows multiple longitudinal-mode operation at 1 064 nm usually. In order to obtain the laser emission at 1 319 nm, key mirror coatings are designed, which suppress the unwanted oscillations in the cavity. The properties of wavelength tuning and longitudinal-mode-selecting of Fabry-Perot etalon are discussed. The output wavelength is tuned by adjusting the tilt angle of etalon and three adjacent longitudinal modes are obtained with two etalons. The 1 319 nm laser's requirements could be satisfied.
The strongest transition of the Nd:YAG occurs at 1 064 nm, which exhibits a fluorescence linewidth of 4～6 cm-1, the Nd:YAG laser shows multiple longitudinal-mode operation at 1 064 nm usually. In order to obtain the laser emission at 1 319 nm, key mirror coatings are designed, which suppress the unwanted oscillations in the cavity. The properties of wavelength tuning and longitudinal-mode-selecting of Fabry-Perot etalon are discussed. The output wavelength is tuned by adjusting the tilt angle of etalon and three adjacent longitudinal modes are obtained with two etalons. The 1 319 nm laser's requirements could be satisfied.
2005,
17.
Abstract:
The dispersion and refractive index inhomogeneity of film materials and error accumulation of layers thickness are all the factors that cause the half-wave hole for a harmonic beam splitter, among them the periodic error accumulation of layer thickness and sensitive layer error is the primary one. Furthermore, the stack structure is also related to the half-wave hole. With the aid of TFCALC the numerical calculations and theoretical analysis were performed. Measures are taken and a harmonic beam splitter was designed and fabricated. The half-wave hole was eliminated fundamentally. Both theoretical and experimental curves are given in this paper, which agree well with each other.
The dispersion and refractive index inhomogeneity of film materials and error accumulation of layers thickness are all the factors that cause the half-wave hole for a harmonic beam splitter, among them the periodic error accumulation of layer thickness and sensitive layer error is the primary one. Furthermore, the stack structure is also related to the half-wave hole. With the aid of TFCALC the numerical calculations and theoretical analysis were performed. Measures are taken and a harmonic beam splitter was designed and fabricated. The half-wave hole was eliminated fundamentally. Both theoretical and experimental curves are given in this paper, which agree well with each other.
2005,
17.
Abstract:
A wavelength separation multilayer with high reflectivity at 1 030 nm and high transmittance at 940 and 980 nm was obtained by optimizing the film stack, such as inserting matching layers, tuning the periodic thickness with the help of thin film design software. The Fabry-Perot configuration was adopted to increase the transmitiance of pass-band. This applicable sample multilayer was carried out by dual ion beam sputtering on BK7 glass. The testing result shows that transmittances of 97.73% and 93.63% are obtained at 940 nm and 980 nm, respectively. A laser induced damage threshold (LIDT) of 35 J/cm2 (1 064 nm, 12 ns) of the separation film is characterized with self-made testing facility.
A wavelength separation multilayer with high reflectivity at 1 030 nm and high transmittance at 940 and 980 nm was obtained by optimizing the film stack, such as inserting matching layers, tuning the periodic thickness with the help of thin film design software. The Fabry-Perot configuration was adopted to increase the transmitiance of pass-band. This applicable sample multilayer was carried out by dual ion beam sputtering on BK7 glass. The testing result shows that transmittances of 97.73% and 93.63% are obtained at 940 nm and 980 nm, respectively. A laser induced damage threshold (LIDT) of 35 J/cm2 (1 064 nm, 12 ns) of the separation film is characterized with self-made testing facility.
2005,
17.
Abstract:
Optical thin films for LD-pumped Nd:YAG/LBO yellow laser at 556 nm are presented in this paper. To achieve 1 112 nm laser action and output 556 nm yellow laser with high power, the coating design of resonator mirrors was analyzed. The spectrum transmittance/reflectance request was reasonably distributed on the two resonator facet reflectivity to restrain the other laser lines such as 946 nm, 1 064 nm and 1 319 nm. The dielectric high reflective laser mirrors was achieved by double ion beam sputter technique for the first time, which was controlled by a time-power monitoring method. When the incident pump power was 2 W, CW 556 nm yellow laser output power of 102 mW was obtained.
Optical thin films for LD-pumped Nd:YAG/LBO yellow laser at 556 nm are presented in this paper. To achieve 1 112 nm laser action and output 556 nm yellow laser with high power, the coating design of resonator mirrors was analyzed. The spectrum transmittance/reflectance request was reasonably distributed on the two resonator facet reflectivity to restrain the other laser lines such as 946 nm, 1 064 nm and 1 319 nm. The dielectric high reflective laser mirrors was achieved by double ion beam sputter technique for the first time, which was controlled by a time-power monitoring method. When the incident pump power was 2 W, CW 556 nm yellow laser output power of 102 mW was obtained.
2005,
17.
Abstract:
A doubly resonant ZnGeP2 (ZGP) optical parametric oscillator pumped by a Tm,Ho:GdVO4 laser is investigated. High pulse repetition frequency of 10 kHz cryogenic Tm(5%),Ho(0.5%):GdVO4 laser at 2.05 μm was utilized as pumping source for ZnGeP2 OPO. The stable pulse train with duration of 23 ns was achieved from Tm,Ho:GdVO4 laser pumped by a continuous wave fiber-coupled laser diode at 801 nm. The GdVO4 host exhibited good thermo-optical property, experiencing greater than 12 kW/cm2 pump density. The ZGP OPO generated a total combined output of 1.2 W at 3.75 μm and 4.52 μm under pumping power of 5.3 W, corresponding conversion efficiency of 23% from incident 2 μm laser power to mid-IR output.
A doubly resonant ZnGeP2 (ZGP) optical parametric oscillator pumped by a Tm,Ho:GdVO4 laser is investigated. High pulse repetition frequency of 10 kHz cryogenic Tm(5%),Ho(0.5%):GdVO4 laser at 2.05 μm was utilized as pumping source for ZnGeP2 OPO. The stable pulse train with duration of 23 ns was achieved from Tm,Ho:GdVO4 laser pumped by a continuous wave fiber-coupled laser diode at 801 nm. The GdVO4 host exhibited good thermo-optical property, experiencing greater than 12 kW/cm2 pump density. The ZGP OPO generated a total combined output of 1.2 W at 3.75 μm and 4.52 μm under pumping power of 5.3 W, corresponding conversion efficiency of 23% from incident 2 μm laser power to mid-IR output.
2005,
17.
Abstract:
The accumulation effect of multi-shot laser-induced damage to optical coatings was investigated. Laser damage testing was performed at 1 064 nm with nanosecond pulses at a pulse length of 12 ns, using an accurate and reliable measurement system. The damage threshold and the number of shots were studied by a statistical method. Compared with the case of single shot laser damage, it is concluded that the microdefects in the optical coatings are responsible for the multiple-pulse damage to mirrors. The damage mechanism can be used to explain the damage process. The expressions for the damage threshold and the number of shots are founded. Nomarski microscope was employed to observe the laser-induced damage morphology after laser irradiation．
The accumulation effect of multi-shot laser-induced damage to optical coatings was investigated. Laser damage testing was performed at 1 064 nm with nanosecond pulses at a pulse length of 12 ns, using an accurate and reliable measurement system. The damage threshold and the number of shots were studied by a statistical method. Compared with the case of single shot laser damage, it is concluded that the microdefects in the optical coatings are responsible for the multiple-pulse damage to mirrors. The damage mechanism can be used to explain the damage process. The expressions for the damage threshold and the number of shots are founded. Nomarski microscope was employed to observe the laser-induced damage morphology after laser irradiation．
2005,
17.
Abstract:
A model which treated the active medium as a thick lens was established to analyze the effects of thermal lens in the resonator. By using the matrix method, the equivalent resonator performance was studied. The uniformity of pump energy distribution was improved. An unstable plane-convex resonant cavity with special parameters was designed based on the calculation result of thermal lens compensation. The optimum radius of the rear convex mirror was presented which could efficiently compensate the effect of thermal lens. A beam divergence less than 1.3 mrad was achieved.
A model which treated the active medium as a thick lens was established to analyze the effects of thermal lens in the resonator. By using the matrix method, the equivalent resonator performance was studied. The uniformity of pump energy distribution was improved. An unstable plane-convex resonant cavity with special parameters was designed based on the calculation result of thermal lens compensation. The optimum radius of the rear convex mirror was presented which could efficiently compensate the effect of thermal lens. A beam divergence less than 1.3 mrad was achieved.
2005,
17.
Abstract:
The thermodynamic model was established for analyzing the temperature and the thermal stress in laser medium. The transient heat conduction equation is the base in the model. First, the longitudinal distribution of the heat deposition power density was got. It was loaded on the corresponding pumping part. The heat capacity, the thermal conductivity, the thermal expansion coefficient and the elastic modulus were fully considered. Thus the distribution and the variation of the temperature and the thermal stress were got. There were references for the experiment and design of heat capacity laser.
The thermodynamic model was established for analyzing the temperature and the thermal stress in laser medium. The transient heat conduction equation is the base in the model. First, the longitudinal distribution of the heat deposition power density was got. It was loaded on the corresponding pumping part. The heat capacity, the thermal conductivity, the thermal expansion coefficient and the elastic modulus were fully considered. Thus the distribution and the variation of the temperature and the thermal stress were got. There were references for the experiment and design of heat capacity laser.
2005,
17.
Abstract:
The development and application background of 2 μm laser were summarized. Two schemes to obtain 2 μm laser were compared and the indirect tunable scheme was adopted.After LD pumped intra-cavity KTP OPO being adopted, the pump peak value power density was increased and high repetition frequency of 2 μm laser was implemented easily. With KTP crystal cut under specifically angle and OPO resonator designed reasonably, 2 μm laser output efficiency was improved effectively. 2 μm laser experiment was performed, and 11.2 W of 2 μm laser output was realized．
The development and application background of 2 μm laser were summarized. Two schemes to obtain 2 μm laser were compared and the indirect tunable scheme was adopted.After LD pumped intra-cavity KTP OPO being adopted, the pump peak value power density was increased and high repetition frequency of 2 μm laser was implemented easily. With KTP crystal cut under specifically angle and OPO resonator designed reasonably, 2 μm laser output efficiency was improved effectively. 2 μm laser experiment was performed, and 11.2 W of 2 μm laser output was realized．
2005,
17.
Abstract:
Based on the nonlinear optics coupled wave equations, a physics model of SBS under focal pumping condition was established and numerical codes were developed. The laser field in fused silica glass when SBS existed was thoroughly evaluated and the damage mechanism was exploited. It is found that the optical-limiting-effect makes the laser intensity decrease in the focus spot to a moderate level. The dependence of SBS process on the laser pulse width and focal length of coupling lens was discussed and an operation state with high efficiency and without laser-induce damage was suggested.
Based on the nonlinear optics coupled wave equations, a physics model of SBS under focal pumping condition was established and numerical codes were developed. The laser field in fused silica glass when SBS existed was thoroughly evaluated and the damage mechanism was exploited. It is found that the optical-limiting-effect makes the laser intensity decrease in the focus spot to a moderate level. The dependence of SBS process on the laser pulse width and focal length of coupling lens was discussed and an operation state with high efficiency and without laser-induce damage was suggested.
2005,
17.
Abstract:
The KTP OPO was studied for frequency conversion of Nd-doped lasers to longer wavelengths and can be used as the basis for eye-safe lidar systems operating in the 1 550 nm wavelength region. One of the major advantages of OPO based on KTP and its isomorphs is the ability to operate with non-critical phase matching (NCPM). The large acceptance angle for NCPM permits efficient OPO operation even with multi-transverse-mode pump lasers. The operation efficiency of KTP optical parametric oscillators (OPO) pumped by multimode Nd:YAG lasers was recently demonstrated. The highest pulse energy(400 mJ )and highest average-power signal output(12 W) of signal output at 1571 nm from a singly-resonant OPO with a 1 J, 30 Hz, Nd:YAG pump laser were obtained. The results provide a clear demonstration that
The KTP OPO was studied for frequency conversion of Nd-doped lasers to longer wavelengths and can be used as the basis for eye-safe lidar systems operating in the 1 550 nm wavelength region. One of the major advantages of OPO based on KTP and its isomorphs is the ability to operate with non-critical phase matching (NCPM). The large acceptance angle for NCPM permits efficient OPO operation even with multi-transverse-mode pump lasers. The operation efficiency of KTP optical parametric oscillators (OPO) pumped by multimode Nd:YAG lasers was recently demonstrated. The highest pulse energy(400 mJ )and highest average-power signal output(12 W) of signal output at 1571 nm from a singly-resonant OPO with a 1 J, 30 Hz, Nd:YAG pump laser were obtained. The results provide a clear demonstration that
2005,
17.
Abstract:
Two kinds of azobenzene polymers (including four samples: films of HMMM-DR1, HMMM-DR19 and films of side-chain azobenzene polymers PCN6 and PCN2) were synthesized and prepared. The HMMM-DR1 and PCN6 were studied and compared with all-optical poling (AOP) technique. Their poling and decaying process were studied and the fundamental AOP properties were described. Double frequency absorption dependence of AOP efficiency of thin films and the trade-off relationship between efficiency of photo-induced second order polarizability of the azobenzene and the transmission efficiency of double frequency were investigated, which are critically important to practical all-optical devices. The quasi-phase matching in the thin film PCN6 was proved and relaxation retardation effect of photo-induced second
Two kinds of azobenzene polymers (including four samples: films of HMMM-DR1, HMMM-DR19 and films of side-chain azobenzene polymers PCN6 and PCN2) were synthesized and prepared. The HMMM-DR1 and PCN6 were studied and compared with all-optical poling (AOP) technique. Their poling and decaying process were studied and the fundamental AOP properties were described. Double frequency absorption dependence of AOP efficiency of thin films and the trade-off relationship between efficiency of photo-induced second order polarizability of the azobenzene and the transmission efficiency of double frequency were investigated, which are critically important to practical all-optical devices. The quasi-phase matching in the thin film PCN6 was proved and relaxation retardation effect of photo-induced second
