Two-stage system based on a software-defined radio for stabilizing of optical frequency combs in long-term...

Area of Science:

• Metrology
• Optical Physics
• Signal Processing

Background:

• Passive optical resonators are crucial for nanometer-scale length measurements.
• Optical frequency combs offer ultimate wavelength references for tunable lasers.
• Traditional analog stabilization systems for optical frequency combs are complex and sensitive.

Purpose of the Study:

• To develop a novel digital signal processing approach for long-term stabilization of femtosecond optical frequency combs.
• To overcome the limitations of traditional analog stabilization methods.
• To enable extended operation of optical frequency combs for precise metrology.

Main Methods:

• Utilizing digital signal processing (DSP) algorithms.
• Implementing a software-defined radio (SDR) for comb stabilization.
• Locking comb repetition and offset frequencies to a radiofrequency (RF) oscillator.

Main Results:

• Achieved long-time stable operation of the optical frequency comb (8 days or more).
• Demonstrated relative frequency stability better than 1.6 × 10⁻¹¹.
• Developed a robust system less sensitive to ambient conditions compared to analog systems.

Conclusions:

• The novel DSP and SDR approach significantly enhances the stability and operational duration of optical frequency combs.
• This advancement facilitates long-term, high-precision length metrology experiments.
• The digital approach offers a more robust and manageable solution for comb stabilization.