Efficiency and Threshold Characteristics of Spectrally Beam Combined High-Power Diode Lasers

The efficiency, threshold characteristics, and the stability of spectral beam combining (SBC) of diode laser array had been studied based on different output couplers (OC). It was found that the lower OC reflectivity, lower internal loss, and shorter cavity-length of emitter were helpful for the realization of high efficiency SBC in an external cavity. However, too low OC reflectivity would also result in an unstable combining with the characteristic of side lobes appeared in far-field and the degraded efficiency. The influence of OC reflectivity on threshold current, lasing spectra, and the beam quality of SBC was investigated and analyzed.