Angular resolved far-field dynamics of (Al,In)GaN laser diodes

We investigate the angularly, temporally, and spectrally resolved far-field dynamics of a single lateral mode green (Al,In)GaN laser diodes. For applications as directly modulated light source in laser projection, for AR/VR/MR, etc., a stable beam pointing angle and width of the far-field is required. Combing an angle- resolved measurement with a spectrometer and streak camera, we characterize optical intensity as function of far-field angle, wavelength, and time. Beam pointing angle and width are then calculated from the moments of the angular intensity distributions. We observe a stable far-field behavior for the narrow ridge. This is in contrast to strong variations in beam pointing direction and far-field profile during short pulses for earlier (Al,In)GaN laser diodes, where the dynamics could be tracked to heating of the waveguide. Therefore we attribute the observed stable dynamics of state-of-the-art narrow ridge laser diodes to their low internal losses, low forward voltage, and consequently low heating.