TUNABLE EXTREMELY LOW-THRESHOLD VERTICAL-CAVITY LASER-DIODES

We have fabricated submilliampere-threshold wavelength tunable three-t erminal vertical-cavity laser diodes by proton implantation and wet ch emical etching. Laser diodes of 8-mum active diameter exhibit record l ow threshold currents of 650 muA and emit up to 170-muW output power u nder CW conditions and 0.4 mW under pulsed excitation. Slightly larger devices of about 12-mum diameter emit up to 1.85 mW in a single mode under pulsed conditions. The emission wavelength is about 970 nm match ed to the spectral gain of the three active InGaAs quantum wells. Indi vidual elements in a two-dimensional array can be continuously tuned o ver 2.2 nm by applying separate tuning currents of 700 muA to the corr esponding top mesa electrode. Tuning and laser currents are controlled independently.