Mode-resolved optical frequency comb fixed point localization via dual-comb interferometry

Area of Science:

• Physics
• Optical Engineering
• Metrology

Background:

• Optical frequency combs are critical tools in metrology and spectroscopy.
• Precisely locating the fixed point of an optical frequency comb is essential for its accurate application.
• Existing methods for fixed-point determination can be complex and limited in precision.

Purpose of the Study:

• To develop and demonstrate improved methods for accurately locating the fixed point of an optical frequency comb.
• To enhance the precision of optical phase tracking (OPT) measurements.
• To validate new methods against established techniques like dual-comb interferometry (DCI).

Main Methods:

• Utilizing two continuous-wave lasers locked to a reference frequency comb.
• Tracking the optical phase of a comb-under-test (CUT) at two distinct frequency points (1.6 THz separation).
• Employing carrier-envelope and optical phase tracking (OPT) and dual-comb interferometry (DCI) for fixed-point determination.

Main Results:

• Achieved precise fixed-point measurements across a wide range of pump modulation frequencies (400 Hz–250 kHz).
• Observed sub-nanometer shifts in the fixed point, indicating high sensitivity.
• DCI measurements closely matched the results obtained from the dual-point tracking method, confirming accuracy.

Conclusions:

• The described dual-point tracking method provides a precise and reliable way to locate optical frequency comb fixed points.
• These improved methods enhance the capabilities of optical frequency combs for advanced scientific applications.
• The findings validate the accuracy and precision of the novel fixed-point determination techniques.