Microwave-resonator-enabled broadband on-chip electro-optic frequency comb generation

Zhaoxi Chen, Yiwen Zhang, Hanke Feng, Yuansong Zeng, Ke Zhang, Cheng Wang*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

3 Citations (Scopus)
8 Downloads (CityUHK Scholars)

Abstract

Optical frequency combs play a crucial role in optical communications, time-frequency metrology, precise ranging, and sensing. Among various generation schemes, resonant electro-optic combs are particularly attractive for their excellent stability, flexibility, and broad bandwidths. In this approach, an optical pump undergoes multiple electro-optic modulation processes in a high-Q optical resonator, resulting in cascaded spectral sidebands. However, most resonant electro-optic combs to date make use of lumped-capacitor electrodes with relatively inefficient utilization of the input electrical power. This design also reflects most electrical power back to the driving circuits and necessitates costly radio-frequency (RF) isolators in between, presenting substantial challenges in practical applications. To address these issues, we present an RF circuit friendly electro-optic frequency comb generator incorporated with on-chip coplanar microwave resonator electrodes, based on a thin-film lithium niobate platform. Our design achieves more than three times electrical power reduction with minimal reflection at the designed comb repetition rate of ∼25 GHz. We experimentally demonstrate broadband electro-optic frequency comb generation with a comb span of >85 nm at a moderate electrical driving power of 740 mW (28.7 dBm). Our power-efficient and isolator-free electro-optic comb source could offer a compact, low-cost, and simple-to-design solution for applications in spectroscopy, high-precise metrology, and optical communications. © 2025 Chinese Laser Press.
Original languageEnglish
Pages (from-to)426-432
JournalPhotonics Research
Volume13
Issue number2
Online published30 Jan 2025
DOIs
Publication statusPublished - 1 Feb 2025

Funding

Research Grants Council, University Grants Committee (CityU 11212721, CityU 11204022, N_CityU113/20); Croucher Foundation (9509005); City University of Hong Kong (9610682).

Publisher's Copyright Statement

  • COPYRIGHT TERMS OF DEPOSITED FINAL PUBLISHED VERSION FILE: © 2025 Chinese Laser Press Chen, Z., Zhang, Y., Feng, H., Zeng, Y., Zhang, K., & Wang, C. (2025). Microwave-resonator-enabled broadband on-chip electro-optic frequency comb generation. Photonics Research, 13(2), 426-432. https://doi.org/10.1364/PRJ.546194

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