Energy efficient 40 Gbit/s transmission with 850 nm VCSELs at 108 fJ/bit dissipated heat

Energy‐efficient oxide‐confined 850 nm vertical‐cavity surface‐emitting lasers (VCSELs) for optical interconnects are presented. Error‐free data transmission at 40 Gbit/s is achieved with a record low dissipated heat per bit (energy efficiency) of only 108 fJ/bit. At 36 Gbit/s across 200 m and at 40 Gbit/s across 50 m of OM3 plus multimode optical fibre error‐free operation is achieved with energy efficiencies of 127 and 119 fJ/bit, respectively.