In some embodiments, a data center optical communications system includes: a transmitter comprising a light source, wherein the light source is configured to provide light; an optical fiber operably connected to said transmitter and configured to receive light from the light source, wherein the optical fiber has a length L of 50 km or greater; a receiver configured to receive light from the optical fiber, wherein the receiver includes a detector for detecting the light, wherein the system has a power consumption of 15 W or less.