Spectral beam combining for a diode laser array by using a grating pair

A grating and a collimating lens are used to replace the transformer lens in the traditional spectral beam combining structure. As a result, the degradation of the beam quality and the cross-talk are prevented. A spectral beam combining with narrow line-width is achieved. A standard semiconductor laser array is employed in this experiment. An output power of 44.8 W and an electro-optic conversion efficiency of 38.9% are achieved. The spectral line-width is 4.1 nm. A beam quality factor of 1.3711.7 in fast and slow axis directions are obtained. The beam quality of the output is close to that of a single emitter of the array in both directions.