Ultra-broadband Kerr microcomb through soliton spectral translation

Abstract

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.

Broadband high-Q multimode silicon concentric racetrack resonators for widely tunable Raman lasers

“…2f . Both Q c and Q L factors exhibit relatively flat variations from 1260 to 1650 nm, indicating the well-designed pulley directional coupler for broadband resonator-waveguide coupling 52 , 65 , 66 . We do not have measurements from 1360 to 1450 nm because of the limited wavelength coverage of pump lasers in our laboratory.…”

“…Even though the multimode resonator has normal dispersion, the presence of the mode and mutual coupling can modify the dispersion for the initialization of modulation instability which can be used for comb generation 53 . The multimode concentric resonators may therefore find applications beyond that demonstrated in the widely tunable Raman laser and may be of interest for use in wideband comb generation 65 , 69 , 70 , or broadband integrated optical parametric oscillators 71 .…”

Parametrically-driven temporal cavity solitons in a bichromatically-driven pure Kerr resonator

“…We begin by discussing the theoretical modelling of bichromatically-driven Kerr resonators. Our starting point is a polychromatic Ikeda-like map, which we will use to derive an extended mean-field Lugiato-Lefever equation that has been used in previous studies [25,[27][28][29][30][31]. To this end, we consider a Kerr resonator made out of a dispersive waveguide [with length L and propagation constant β(ω)] that is driven with two coherent fields with angular frequencies ω ± = ω 0 ± Ω p [see Fig.…”

“…Whilst this question has been previously explored in the context of diffractive Kerr-only resonators [24], the presence of dispersion substantially changes the physics of the problem. The impact of bichromatic driving in the dynamics of conventional Kerr CSs has also been considered [25][26][27][28][29][30], but to our knowledge, no work has yet explored the possibility of using the scheme to generate parametrically-driven CSs in pure Kerr resonators.…”

Dissipative solitons and switching waves in dispersion folded Kerr cavities

“…Given the relative maturity of research into the physics of dissipative Kerr structures, greater attention has been given to exploring physics and microcomb generation in non-trivial regimes. These regimes include alternative pumping schemes such as pulse-driving [15] and self-injection locked lasers [16,17], and the use of complex dispersion profiles to extend * tobias.kippenberg@epfl.ch the comb bandwidth of solitons with dispersive waves (DWs) [18,19]. Complex resonator structures are now the object of attention, including in particular resonators with integrated Bragg or photonic-crystal elements [20], and dual coupled-ring photonic 'dimers' [21] or photonic 'molecules' [22].…”