Energy-efficient and temperature-stable oxide-confined 980 nm VCSELs operating error-free at 38 Gbit/s at 85°C

980 nm vertical-cavity surface-emitting lasers (VCSELs) operating error-free at 38 Gbit/s at 85°C with record 177 fJ of dissipated heat per bit are presented. The VCSELs are particularly well suited for short, very-short and ultra-short-reach interboard, chip-to-chip and intrachip optical interconnects, where temperature stability, bandwidth and VCSEL density and the minimisation of waste heat are critical. Error-free operation at 40 Gbit/s at 75°C and at 42 Gbit/s at 25°C is achieved. To date, 980 nm VCSELs are the most energy-efficient of all VCSELs at 85°C at any wavelength.