Apparatus and methods for power efficient multi-format optical transmission

A transmitter for generating a differential phase shift keyed (DPSK) optical signal, the apparatus comprising:

• a DPSK encoder to convert a data signal into a pre-coded DPSK signal;
• a first driver, operably coupled to the DPSK encoder, to convert the pre-coded DPSK signal into a first drive signal;
• a laser, operably coupled to the first driver, to emit a first optical signal in response to the first drive signal, the first optical signal having a phase shift depending on an amplitude of the first drive signal;
• a spectral filter, in optical communication with the laser and characterized by a spectral pass band, to spectrally filter the first optical signal;
• a temporal filter, in optical communication with the laser, to temporally filter the first optical signal so as to yield the DPSK optical signal;
• and
• a second driver, operably coupled to the laser, to generate a second drive signal, the second drive signal causing the laser to generate an optical beam having a wavelength outside the spectral pass band of the first filter,
• wherein the second driver is configured to change a duty cycle of the DPSK optical signal between about 2.5% and about 100%.