Improving efficiency of spectral beam combining by optimizing reflectivity of output coupler for laser diode array

This paper reports a study on the relationship between the combining efficiency and reflectivity of output coupler of diode array in spectral beam combining. The combining efficiency is analyzed theoretically by using principle of the resonator. The simulation shows that high reflectivity will lead to low combining efficiency, and low reflectivity may cause the failure of wavelength locking. With increasing of the reflectivity of the OC, the combining efficiency changes like a downward parabola which has a maximum value of ~10%. The experiments demonstrate that the highest efficiency is obtained at a reflectivity of 10%, and the experimental results agree well with the theoretical analysis.