Spectral and spatial dynamics of a multimode GaN-based blue laser diode

High-resolution spectral analysis of a multimode GaN-based blue laser diode was performed as a function of temperature and current both below and above the threshold levels. Maps of longitudinal modes evolution as a function of current and temperature were obtained from the highly resolved emission spectra of the laser diode. The evolution of emitted longitudinal modes with current and temperature exhibited redshifts at rates of 0.0059 nm/mA and 0.0149 nm/°C, respectively. Similarly, the laser gain profile was observed to shift towards longer wavelengths but with rates of 0.022 nm/mA and 0.0439 nm/°C. The longitudinal mode spacing of 0.0540 nm was experimentally evaluated and compared with its equivalent theoretically predicted value.