Broadband electro-optic frequency comb generation in a lithium niobate microring resonator

Area of Science:

• Photonics
• Optical Engineering
• Materials Science

Background:

• Optical frequency combs are crucial for optical communication, metrology, timing, and spectroscopy.
• Existing comb generation methods, like mode-locked lasers and Kerr nonlinearity, have limitations in spectrum width and integration.
• Electro-optic (EO) combs offer stability and controllability but were previously limited by narrow widths and weak interactions.

Purpose of the Study:

• To overcome limitations of previous EO combs by developing an integrated EO comb generator.
• To achieve wider spectra and enhanced controllability in EO comb generation.
• To explore the potential of integrated EO combs for advanced applications.

Main Methods:

• Development of an integrated EO comb generator on a thin-film lithium niobate photonic platform.
• Leveraging the platform's large EO response, ultralow optical loss, and co-localized fields.
• Implementing dispersion engineering for enhanced comb generation.

Main Results:

• Demonstrated an EO comb spanning more frequencies than the telecommunications L-band (over 900 lines).
• Showcased future potential for octave-spanning combs with dispersion engineering.
• Achieved fine control over frequency spacing (10 Hz to 100 MHz) and generated dual-frequency combs.

Conclusions:

• Integrated EO comb generators can produce wide and stable optical frequency comb spectra.
• The reconfigurability of these integrated EO combs complements integrated Kerr combs.
• These devices enable diverse applications, including spectroscopy and optical communications.