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Compact sub-hertz linewidth laser enabled by self-injection lock to a sub-milliliter FP cavity
Optics Letters
|March 1, 2023
Summary
We developed a compact narrow linewidth laser (NLL) using a miniature Fabry-Perot cavity. This NLL achieves exceptional frequency stability and a linewidth of 60 mHz, surpassing commercial NLLs for advanced applications.
Area of Science:
- Optics and Photonics
- Laser Technology
- Quantum Technologies
Background:
- Narrow linewidth lasers (NLLs) with high frequency stability and small form factors are crucial for applications like long-range sensing, quantum information processing, and atomic clocks.
- Existing high-performance NLLs often rely on complex laboratory setups, such as Pound-Drever-Hall (PDH) lock or self-injection lock (SIL) systems coupled with vacuum-stabilized Fabry-Perot (FP) cavities, which are bulky and sensitive to environmental factors.
Purpose of the Study:
- To demonstrate a compact, high-performance NLL that bypasses the need for complex stabilization systems.
- To achieve superior frequency stability and narrow linewidth in a small-volume laser system.
Main Methods:
- Utilized self-injection lock (SIL) of a diode laser to a miniature Fabry-Perot (FP) cavity with an ultrahigh quality (Q) factor of 7.7 × 108 and a volume of 0.5 mL.
- The compact NLL system has a total volume of 67 mL, eliminating the need for table-size vacuum systems and extensive thermal/vibration isolation.
- Characterized the laser's performance using a self-delayed heterodyne system.
Main Results:
- Achieved a Lorentzian linewidth as narrow as 60 mHz.
- Measured an integrated linewidth of approximately 80 Hz.
- Demonstrated frequency noise performance superior to commercial NLLs and recently reported hybrid-integrated NLLs.
Conclusions:
- The developed compact NLL, utilizing an ultrahigh-Q FP cavity, represents a significant advancement toward field-deployable laser systems.
- This work paves the way for practical implementation of high-performance NLLs in various demanding applications by overcoming the limitations of traditional complex setups.
