Methods and apparatus for emulating optical modules. A method includes receiving, from an optical module emulator, a first serial data stream having the plurality of upstream signals multiplexed into a plurality of bits; wherein the first data stream includes a plurality of frames, each frame having a multi-frame alignment bit; and de-multiplexing the plurality of upstream signals based on each multi-frame alignment bit within each respective frame. A method includes receiving, from an emulator controller, a second serial data stream having a plurality of downstream signals multiplexed into a plurality of bits; wherein the second serial data stream includes a plurality of frames, each frame having a multi-frame alignment bit; and de-multiplexing the plurality of downstream signals based on each multi-frame alignment bit within each respective frame.