Self-sustained pulsation in 650 nm band AlGaInP visible-laser diodes with highly doped saturable absorbing layer

650-nm band self-sustained-pulsing AlGaInP laser diodes having very low intensity noise characteristics were successfully demonstrated by adopting novel structure, which has highly doped saturable absorbing layer for the first time. Short carrier lifetime, which is indispensable for self-sustained pulsation, was realized by applying high doping to the absorbing layer. 500-μm-long devices with the lasing wavelength of 656 mm were fabricated, resulting in the threshold current of 65 mA at room temperature. The relative intensity noise (RIN) was below -138 dB/Hz in the temperature ranging from 20-50/spl deg/C at 5 mW.