Optical sampling system for simultaneously monitoring intensity modulation and frequency modulation
AssigneeNippon Telegraph and Telephone Corporation
InventorFumihiko Ito
Life of this patent
Estimating the term…
Abstract
The optical sampling system performs by detecting the interference effect which is a linear correlation between the signal lights and the optical pulses, so that both the signal lights and the optical pulses can have relatively low intensities, and the reception sensitivity is high. Also, the pulse width of the optical pulses and the amount of delay given to the optical pulses are the only factors that limit the time resolution, so that it is possible to provide the optical sampling system with excellent time resolution and power consumption properties, and it is possible for the optical sampling system to monitor not only the intensity of the signal lights but also the frequency modulation component as well.
Claims12
An optical sampling method for monitoring repeatedly entered high speed signal lights, comprising the steps of:
- generating 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, from an optical pulse generation unit;
- splitting each of the signal lights and the optical pulses into two parts by respective splitters;
- delaying a split part of either the signal lights or the optical pulses for a prescribed period of time by a delay unit;
- inputting one split part of the signal lights and one split part of the optical pulses into a first optical hybrid, while inputting the delayed split part of the signal lights or the optical pulses and the other split part of either the signal lights or the optical pulses whichever was not delayed into a second optical hybrid;
- receiving output lights from the first optical hybrid at first and second balanced optical receivers, and outputting first and second currents;
- receiving output lights from the second optical hybrid at third and fourth balanced optical receivers, and outputting third and fourth currents;
- and
- obtaining a frequency modulation component of the signal lights by calculation processing using values of the first to fourth currents by a calculation processing device.
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 part of the signal lights and one split part of the optical pulses inputted therein;
- a second optical hybrid configured to have the delayed split part of the signal lights or the optical pulses and the other split part of either the signal lights or the optical pulses whichever was not delayed 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 third and fourth currents;
- and
- a calculation processing device configured to obtain a frequency modulation component of the signal lights by calculation processing using 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 part of the signal lights and one split part of the optical pulses inputted therein;
- a second optical hybrid configured to have the delayed split part of the signal lights or the optical pulses and the other split part of either the signal lights or the optical pulses whichever was not delayed 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 third 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 calculation processing using values of the first to fourth currents.
Dependencies are inferred from the claim text.