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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
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Phase-locking transition in Raman combs generated with whispering gallery mode resonators.
Optics Letters
|August 13, 2016
Summary
We demonstrate phase locking in Raman optical frequency combs using ultrahigh Q resonators. These highly coherent combs, achieved with low pump power, exhibit wide spectral spans and narrow microwave beat signals.
Area of Science:
- Optics
- Quantum Optics
- Resonator Optics
Background:
- Raman optical frequency combs (ROFCs) are generated in high-Q resonators.
- Phase locking is crucial for comb applications but challenging to achieve in ROFCs.
- Whispering gallery mode (WGM) resonators offer high Q-factors for efficient nonlinear processes.
Purpose of the Study:
- Investigate mechanisms for phase locking in ROFCs.
- Explore different operational regimes of ROFC generation.
- Characterize the coherence and spectral properties of phase-locked ROFCs.
Main Methods:
- Utilizing ultrahigh Q crystalline WGM disk resonators.
- Experimentally controlling pumping conditions to trigger different lasing regimes.
- Measuring beat signal spectra to monitor phase locking and coherence.
Main Results:
- Observed single-frequency Raman lasing, multimode operation, and Kerr-assisted ROFC generation.
- Achieved phase-locked combs with high coherence and wide spectral spans.
- Obtained combs with pump powers of a few tens of mW.
- Reported ROFCs with multiple free-spectral range spacings.
- Measured microwave beat signals with a 3 dB linewidth < 50 Hz, confirming phase locking.
Conclusions:
- Phase locking in ROFCs is achievable in various regimes with ultrahigh Q resonators.
- Low pump powers are sufficient for generating high-coherence, phase-locked combs.
- The demonstrated phase-locked ROFCs are promising for applications requiring precise frequency control.
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