US Patent 10009108 Coherent and pulse amplitude modulation in a pluggable optical transceiver

An apparatus adapted to operate a pluggable optical transceiver in a plurality of modulation schemes includes core circuitry adapted to interface with a host device, wherein the host device is adapted to support the pluggable optical transceiver; direct detection modulation circuitry communicatively coupled to the core circuitry; coherent modulation circuitry communicatively coupled to the core circuitry; and selection circuitry adapted to operate one of the direct detection modulation circuitry and the coherent modulation circuitry based on a selection depending on an application of the pluggable optical transceiver.