Semiconductor Lasers: Recent Advancesand Prospects

Semiconductor lasers have made exciting progress in performance over the last few years with prospective applications e.g. in optical communications and data storage, metrology, display technology, material processing, or solid state laser pumping. The short wavelength limit of semiconductor laser emission has now been pushed to 410 nm using GaN based devices. High power broad area lasers in the well established InAlGaAs material system offer several 10 W continuous output power at power conversion efficiencies above 60%. Beam profile control is obtained in hybrid or monolithic master oscillator power amplifier (MOPA) configurations. Communication laser diodes show small signal current modulation bandwidths 40 GHz and are applied for 20 Gbit/s data transmission. Extremely low laser threshold currents of less than 10µA as well as more than 50% conversion efficiency at 1 mW output power are reported from novel selectively oxidized vertical cavity surface emitting laser diodes (VCSELs).