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Distortion-corrected phase demodulation using phase-generated carrier with multitone mixing.
Optics Express
|December 31, 2020
Summary
We developed a new phase generated carrier (PGC) demodulation technique for homodyne interferometers. This method corrects distortion caused by modulation depth variations and intensity fluctuations without adding noise.
Area of Science:
- Optical interferometry
- Signal processing
Background:
- Homodyne interferometers are sensitive to environmental and source fluctuations.
- Standard phase generated carrier (PGC) demodulation can suffer from distortion due to modulation depth variations.
Purpose of the Study:
- To present a novel PGC demodulation technique robust to modulation depth variations and source intensity fluctuations.
- To provide real-time DC component of phase without prior data or ellipse fitting.
Main Methods:
- Digitally mixing the interferometric waveform with a multitone synthetic function.
- Utilizing a linear combination of harmonics of the modulating signal.
- Implementing the technique with only two mixers.
Main Results:
- Achieved negligible distortion even with large modulation depth variations.
- Successfully provided real-time DC component of phase.
- Validated the technique with simulated data and experimental wavelength metering data from an on-chip interferometer.
- Demonstrated distortion correction without increasing noise compared to standard PGC.
Conclusions:
- The novel PGC demodulation technique offers improved robustness and real-time capabilities for homodyne interferometry.
- This method is suitable for applications like wavelength metering where stability is crucial.
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