Continuous-wave operation of 1.55-μm vertical-cavity surface-emitting laser with digital-alloy active region using submonolayer superlattices

For the first time, a digital-alloy active region (DAAR) consisting of submonolayer superlattices was used in a 1.55-μm vertical-cavity surface-emitting laser. The device showed continuous-wave operation with a room-temperature threshold current (I/sub th/) of 1.2 mA, maximum output power (P
_max
) of 0.26 mW, and a differential quantum efficiency (/spl eta//sub d/) of 21%. These results indicate that the DAAR is at least as efficient as the analog-alloy active region and provides much better control of alloy composition and strain.