30 GHz bandwidth 850 nm VCSEL with sub‐100 fJ/bit energy dissipation at 25–50 Gbit/s

A high‐speed and energy‐efficient oxide‐confined 850 nm vertical‐cavity surface‐emitting laser (VCSEL) for optical interconnects is presented. A record‐high modulation bandwidth of 30 GHz is reached for a 3.5 µm oxide aperture VCSEL, with 25 GHz bandwidth already at a bias current of 1.8 mA. The high bandwidth at low currents enables energy‐efficient transmission with a dissipated heat energy in the VCSEL of <100 fJ/bit at 25, 40 and 50 Gbit/s.