Far field output distribution features for spectral beam combining of diode laser array stack in an external cavity

We present the design and the experimental implementation of spectral beam combining of diode laser bars, which contains six 800 nm Mini-Bars along the fast-axis direction in an external cavity. The output power of 175 W with its efficiency of 62% is achieved at 60 A of operating current. For better applications, some of output features need to be uncovered. In this work, the far field distribution of lobes is studied. The variation tendency of efficiencies with pump currents and the distribution of spectrum are measured. The distribution of the spectrum with the angle between the axis of output laser and the axis of central wavelength is simulated. The result shows that 1. the efficiency decrease slowly with current increasing. 2.it is measured that Beam Parameter Product of main lobe along the slow axis considered by one-dimension, 3.05 mm × mrad, is close to that of single emitter. 3. it is verified that mutual locked mode generate side lobes effecting both beam quality and efficiency.