Phase locked broad-stripe diode laser array in an external cavity

By using an external cavity, a commercially available broad-stripe semiconductor diode laser array(DLA) has been phase locked. Measurements show that the spectral width of the phase-locked DLA is reduced to 0.16 nm compared to 1.9 nm of the free-running DLA, and the peak wavelength is shifted from 803.8 nm to 805.5 nm. An angular spacing between the lobes of the far field pattern of 1.6 mrad, coincident with the ratio of the wavelength to emitter distance, indicates that the DLA is operated in the fundamental(or highest) super mode. The modulation depth of the peak-valley pattern is measured to be larger than 0.8. It has also been verified that phase locking can be achieved for external cavity length between 1/10 to 1/16 of the Talbot distance zT. Based on experimental facts, it is believe