Low noise characteristics of AlGaInN-based self-pulsating laser diodes

We have successfully realized practical self-pulsating laser diodes (SP-LDs) based on AlGaInN systems that exhibit low noise characteristics even with an optical feedback of 1% at a high temperature of 75 degrees C. Our fabricated SP-LD employs a saturable absorber layer (SAL). We adopt new approaches to realize practical SP operation; specifically, (i) we inserted an AlGaN layer between the active layer and the SAL in order to reduce the threshold current, and (ii) we intentionally introduced reactive ion etching (RIE) damage to the SAL in order to reduce the carrier lifetime in the SAL by controlling the distance between the SAL and the dry-etched surface. The threshold currents for the fabricated SP-LD at 25 degrees C and 75 degrees C were 38.8 mA and 54.4 mA, respectively. We also demonstrated that it is possible to suppress the relative intensity noise (RIN < - 125 dB/Hz) even under the conditions of high temperature (75 degrees C) and an optical feedback of 1%. These results indicate that practical SP-LDs for use in optical storage devices can be realized by inducing dry etching damage in the SAL.