Emitter-Resolved Characterization of High-Power Diode Laser Bars at Operating Point and Below Threshold

In this letter, we report on a novel measurement setup for emitter resolved characterization of polarization, optical output power, wavelength, and slow-axis intensity distribution of high-power diode laser bars. Our setup enables the emitter-resolved characterization in a range starting from below the laser threshold reaching up to several 100 amps correlating to operating power of the state-of-the-art generation of diode laser bars, which possess a power output of several 100 watts. In contrast to previous works, the properties are determined directly from the laser radiation during operation, which enables us to directly correlate the emitter-resolved power and polarization distribution. In addition to the reduction in degree of polarization towards the edge emitters, we demonstrate a disparity in power distribution among the edge emitters at operating output power in comparison to operation below the laser threshold. To distinguish between thermal and stress-induced effects, we operate the diode laser bar both in cw- and pulsed mode. Furthermore, we demonstrate how the effects of mechanical stress on the performance and degree of polarization of the edge emitters at operating power are identified.