High-temperature, high-power self-pulsating 635 nm laser diodes

The next generation of optical data systems will be based upon visible AlGalnP laser diodes operating at wavelengths between 630-680 nm. One important application for visible diodes is the optical “read” head of the data storage system. The most important requirement of the read laser is a low noise figure, typically measured as relative intensity noise (RIN), achieved across a broad temperature range at the operating power of the read system. One approach to achieving a very low noise diode is to design the laser diode to self-pulsate. The self-pulsation of the laser diode destroys many coherence effects and leads to a general reduction in RIN and greatly improved resistance to optical feedback. In the paper, data are presented on 635 nm self-pulsating laser diodes that achieve an average self-pulsating output power of 25 mW at 25°C and show distinct self-pulsation to temperatures as high as 100°C. The characteristic temperature of the self-pulsating laser diode is 230 K over the temperature range from 25°C to 80°C. The lasers described here use AlGaInP epitaxial layers grown lattice-matched on n-type GaAs substrates