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Ultra-broadband Kerr microcomb through soliton spectral translation

TitleUltra-broadband Kerr microcomb through soliton spectral translation
Publication TypeJournal Article
Year of Publication2021
AuthorsG. Moille, E. F. Perez, J. R. Stone, A. Rao, X. Lu, T. Sami Rahman, Y. K. Chembo, and K. Srinivasan
JournalNat. Commun.
Date PublishedDEC 14
Type of ArticleArticle

Broadband and low-noise microresonator frequency combs (microcombs) are critical for deployable optical frequency measurements. Here we expand the bandwidth of a microcomb far beyond its anomalous dispersion region on both sides of its spectrum through spectral translation mediated by mixing of a dissipative Kerr soliton and a secondary pump. We introduce the concept of synthetic dispersion to qualitatively capture the system's key physical behavior, in which the second pump enables spectral translation through four-wave mixing Bragg scattering. Experimentally, we pump a silicon nitride microring at 1063 nm and 1557 nm to enable soliton spectral translation, resulting in a total bandwidth of 1.6 octaves (137-407 THz). We examine the comb's low-noise characteristics, through heterodyne beat note measurements across its spectrum, measurements of the comb tooth spacing in its primary and spectrally translated portions, and their relative noise. These ultra-broadband microcombs provide new opportunities for optical frequency synthesis, optical atomic clocks, and reaching previously unattainable wavelengths. Integrated optical frequency measurements, benefit from broadband on-chip frequency combs. Here the authors present a low-noise microcomb whose span extends from telecom to near-visible wavelengths. Here the authors present a dissipative Kerr soliton formation approximated by introducing the concept of synthetic dispersion.