Output characteristics of diode laser array by three different spectral beam combing structures

Based on spectral beam combining technology, with diffraction grating and external cavity feedback, each element of an array of diode laser is locked at different wavelengths in a narrow linewidth by inserting a beam shaping system. And the output beam is an approximately parallel light along the direction of combination. Beam quality improvement and linewidth narrowing of an array of diode laser are achieved. The standard diode laser array used in our experiment has 19 elements, with a width of 100 m and a period of 500 m for each element. Experiment is conducted on different spectral beam combing setups, including spectral beam combing after collimation in both fast and slow axes, spectral beam combing after beam shaping and beam combing in an external cavity with narrow-line width. The combining output beam has the same beam quality as that of a single emitter and the linewidth of such a beam is narrow. The experiment results are analyzed.