Phase-diverse coherent optical spectrum analyzer

A phase-diverse coherent optical spectrum analyzer comprising:

• a narrow-band optical receiver comprising:
• a first input for receiving a first optical input signal;
• a second input for receiving a second optical input signal;
• and
• an optical coupler for receiving said first optical input signal and said second optical input signal, and producing at least three optical output signals based on said first optical input signal and said second optical input signal, wherein said optical coupler combines
• said first optical input signal and said second optical input signal;
• a detector unit for converting said optical output signals into corresponding electrical output signals allowing for mixing of said first optical input signal and said second optical input signal;
• and
• a processing unit for isolating heterodyne signals from said electrical output signals, said heterodyne signals comprising a first signal and a second signal such that phase diversity of the heterodyne components between said first input signal and said second input signal is achieved by said phase-diverse coherent optical spectrum analyzer.

A method for analyzing an optical signal comprising:

• receiving a first optical input signal at a narrow-band optical receiver of a phase-diverse coherent optical spectrum analyzer;
• receiving a second optical input signal at said narrow-band optical receiver;
• producing a first output signal, a second output signal, and a third output signal based on mixing said first optical input signal and said second optical input signal;
• isolating heterodyne components of said first output signal, said second output signal and said third output signal, said heterodyne components comprising a first quadrature signal and a second quadrature signal such that phase diversity of the heterodyne mixing between said first input signal and said second input signal is achieved by said phase-diverse coherent optical spectrum analyzer.