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Generation and Coherent Control of Pulsed Quantum Frequency Combs
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Phase noise characterization of a Cr:ZnS frequency comb using subspace tracking
Optics Letters
|March 14, 2025
Summary
We characterized the phase noise of a mid-IR Cr:ZnS frequency comb, crucial for dual-comb spectroscopy. Common mode noise dominates, with other noise terms below the detection limit.
Area of Science:
- Quantum optics
- Spectroscopy
- Laser physics
Background:
- Mid-infrared (mid-IR) Cr:ZnS lasers are emerging as powerful tools for high-resolution dual-comb spectroscopy (DCS).
- Detailed phase noise characterization is essential for optimizing DCS performance but has been lacking for Cr:ZnS combs.
Purpose of the Study:
- To conduct a comprehensive phase noise characterization of a mid-IR Cr:ZnS frequency comb.
- To investigate common mode, repetition rate, and high-order phase noise terms and their dependence on comb-line number.
Main Methods:
- Utilized a recently developed phase noise measurement technique based on multi-heterodyne detection and subspace tracking.
- Employed a single measurement setup to capture various phase noise components simultaneously.
- Quantified phase noise terms and their scaling with comb-line number.
Main Results:
- Demonstrated that common mode phase noise is the dominant noise source in the Cr:ZnS frequency comb.
- Found that repetition rate and high-order phase noise terms are below the measurement noise floor (approximately -120 dB rad²/Hz).
- Identified that these lower-order noise terms are not discernible with the current measurement sensitivity.
Conclusions:
- The phase noise of the mid-IR Cr:ZnS frequency comb is primarily governed by common mode noise.
- The sensitivity of the measurement technique is sufficient to identify dominant noise sources.
- Further improvements in measurement sensitivity may be required to resolve lower-level phase noise contributions.
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