High-Power AlGaInN Laser Diodes with High Kink Level and Low Relative Intensity Noise

High-power AlGaInN laser diodes (LDs) with both high kink level and low relative intensity noise (RIN) are successfully fabricated. A kink level of higher than 100 mW is obtained by using a new ridge structure and by narrowing the ridge width down to 1.5 µm. This structure consists of a thin Si on SiO2 multiple buried layers instead of the conventional thick SiO2 buried layer. The low RIN of these devices is obtained by decreasing the threshold current; under optical feedback with high-frequency modulation, the RIN values are as low as -125 dB/Hz. As the RIN of these devices exhibits a tendency to deteriorate with increasing operating current, the lifetime criterion was redefined as the point at which the operating current has increased by 20%. Even under this stricter lifetime criterion, the estimated lifetime of these LDs exceeds 15,000 h under 30 mW cw operation at 60°C.