Azimuthal Kerr combs with predictable mode spacing in surface nanoscale axial photonic microresonators

Area of Science:

• Photonics
• Materials Science
• Fiber Optics

Background:

• Optical frequency combs are crucial for precision measurement and spectroscopy.
• Generating frequency combs in compact microresonators is an active research area.
• Surface nanoscale axial photonic microresonators (SNAPRs) offer a new platform for photonic device integration.

Purpose of the Study:

• To demonstrate the first generation of optical frequency combs in SNAPRs.
• To investigate the feasibility of using continuous-wave light pumping for comb generation in these structures.
• To analyze the spectral characteristics of frequency combs produced by SNAPRs of varying dimensions.

Main Methods:

• Fabrication of SNAPRs in silica optical fibers using localized heating.
• Pumping the SNAPRs with continuous-wave light.
• Characterization of the generated optical frequency combs using optical spectrum analyzers.

Main Results:

• Successfully generated optical frequency combs in SNAPRs for the first time.
• Observed consistent spectral spacing across SNAPRs with different fiber diameters (220 µm, 440 µm, 660 µm).
• Experimental spectral spacing matched theoretical predictions for untreated fibers, indicating robustness of the fabrication process.

Conclusions:

• SNAPRs are a viable new platform for generating optical frequency combs.
• The fabrication method yields reproducible results without requiring fine-tuning.
• This breakthrough opens possibilities for miniaturized and integrated frequency comb sources.