Optical sampling system for simultaneously monitoring intensity modulation and frequency modulation

An optical sampling system for monitoring repeatedly entered high speed signal lights, comprising:

• an optical pulse generation unit configured to generate optical pulses with an optical pulse width shorter than an inverse of a frequency variation of the signal lights, which has a period slightly different from a repetition period of the signal lights;
• splitters configured to split each of the signal lights and the optical pulses into two parts;
• a delay unit configured to delay a split part of either the signal lights or the optical pulses for a prescribed period of time;
• a first optical hybrid configured to have one split parts of the signal lights and the optical pulses inputted therein;
• a second optical hybrid configured to have other split parts of the signal lights and the optical pulses inputted therein;
• first and second balanced optical receivers configured to receive output lights from the first optical hybrid, and output first and second currents;
• third and fourth balanced optical receivers configured to receive output lights from the second optical hybrid, and output this and fourth currents;
• and
• a calculation processing device configured to obtain a frequency modulation component of the signal lights by carrying out a calculation processing with respect to values of the first to fourth currents.

A computer program product for causing a computer to function as a calculation processing device for obtaining a frequency modulation component of signal lights in an optical sampling system for monitoring repeatedly entered high speed signal lights, formed by:

• an optical pulse generation unit configured to generate optical pulses with an optical pulse width shorter than an inverse of a frequency variation of the signal lights, which has a period slightly different from a repetition period of the signal lights;
• splitters configured to split each of the signal lights and the optical pulses into two parts;
• a delay unit configured to delay a split part of either the signal lights or the optical pulses for a prescribed period of time;
• a first optical hybrid configured to have one split parts of the signal lights and the optical pulses inputted therein;
• a second optical hybrid configured to have other split parts of the signal lights and the optical pulses inputted therein;
• first and second balanced optical receivers configured to receive output lights from the first optical hybrid, and output first and second currents;
• third and fourth balanced optical receivers configured to receive output lights from the second optical hybrid, and output this and fourth currents;
• the computer program product comprising:
• a computer program code for causing the computer to obtain a frequency modulation component of the signal lights by carrying out a calculation processing with respect to values of the first to fourth currents.