Basic Properties, Linewidth Enhancement Factor and Spectral Linewidth of SQW Laser Diodes Emitting in the 780 nm Region

GRIN-SCH-SQW laser diodes with quite a narrow well width of 3 nm were successfully fabricated by MOVPE. Oscillation wavelength and dispersion of linewidth enhancement factor α were found to be greatly dependent on cavity length i.e. threshold level. α measured at oscillation wavelength was 2.1 in the 300 µm-long laser, and 3.7 in the 1000 µm-long laser. This dependence was roughly explained by taking account of bandgap shrinkage and broadening of the gain spectrum. The narrowest spectral linewidth obtained was 1.5 MHz at an output power of 8.7 mW with a linewidth-power product of 5.7 MHz·mW in the 1000 µm-long laser.