Methods and systems for optical detection

An apparatus comprising:

• a single-polarization receiver front end that detects a signal including a symbol having a pulse position modulation (PPM) pulse;
• an analog-to-digital convertor (ADC) that converts the detected signal into a digital component;
• and
• a processor, operably coupled to the single-polarization receiver and the ADC, the processor configured to decode a first non-zero portion of a plurality of bits carried by the symbol based on a position of the PPM pulse.

An optical communication method, comprising:

• receiving a signal at a receiver;
• detecting, through the receiver, a signal including a symbol with an independent pulse position modulation (PPM) pulse and an additional modulation;
• recovering two polarization components from the detected signal, each of the polarization components carrying independent data in different timeslots;
• decoding a first portion of bits carried by the symbol based on a position of the PPM pulse;
• and
• decoding a second portion of the bits based on the additional modulation.

An optical communication method, comprising:

• receiving a signal at a coherent receiver;
• detecting, through the coherent receiver, the signal including a symbol with a pulse position modulation (PPM) pulse;
• recovering a first and a second frequency of the detected signal;
• and
• decoding a first non-zero portion of bits carried by the symbol based on a position of the PPM pulse.