Spectral Purification of Microwave Signals with Disciplined Dissipative Kerr Solitons

Abstract

Continuous-wave-driven Kerr nonlinear microresonators give rise to self-organization in terms of dissipative Kerr solitons, which constitute optical frequency combs that can be used to generate low-noise microwave signals. Here, by applying either amplitude or phase modulation to the driving laser we create an intracavity potential trap to discipline the repetition rate of the solitons. We demonstrate that this effect gives rise to a novel spectral purification mechanism of the external microwave signal frequency, leading to reduced phase noise of the output signal. We experimentally observe that the microwave signal generated from disciplined solitons is injection-locked by the external drive at long time scales, but exhibits an unexpected suppression of the fast timing jitter. Counter-intuitively, this filtering takes place for frequencies that are substantially lower than the cavity decay rate. As a result, while the long-time-scale stability of the Kerr frequency comb's repetition rate is improved by more than 4 orders of magnitude, the purified microwave signal shows a reduction of the phase noise by 30 dB at offset frequencies above 10 kHz.

Formation and Collision of Multistability-Enabled Composite Dissipative Kerr Solitons

“…(b) The evolutions of the VNA response (b1), the repetition rate spectra (b2), and the power fluctuation spectra (b3) as the primary pump-resonance detuning is varied from 30 to 40 MHz and then back to 30 MHz. The jumps of the primary f rep around 37 MHz are attributed to a strong single dispersive wave[11] that we confirm by comparing the acquired microcomb spectra before and after the jump. The range where the state of soliton collision is switched on is denoted by the red dashed lines.…”

“…In recent years, a particular type of cavity solitons-temporal solitons in dissipative systems [3] with Kerr nonlinearity, also known as dissipative Kerr solitons (DKSs)-have been attracting surging research interest in platforms ranging from bulk free-space cavities [4] and fiber ring resonators [5] to microresonators of a variety of host materials [6,7]. In particular, DKSs generated in microresonators are, on the one hand, promising for numerous applications including spectroscopy [8,9], low-noise microwave generation [10,11], imaging [12], and telecommunication [13] as they produce miniaturized and coherent frequency combs (microcombs). On the other hand, DKSs exhibit a plethora of interesting phenomena such as Stokes solitons [14], soliton breathers [15][16][17], and soliton crystals [18].…”

Ultralow-noise photonic microwave synthesis using a soliton microcomb-based transfer oscillator

“…The mutual harmonic phase-locking of the comb repetition rates is achieved via soliton injection-locking 32 . The harmonic M = 56 of the repetition rate of the auxiliary comb (at 14.093 GHz) is detected, filtered and amplified to phase-modulate the pump light using an electrooptic modulator (EOM, blue box in Fig.…”

Emerging material systems for integrated optical Kerr frequency combs

“…In this technique, phase modulation of the CW pump creates a spatially varying loss and gain profile in the cavity [275,415] and can create detuning ranges where the multi-stability is fully lifted and a single-peak DKS is the only possible microcomb state [414]. Pump phase or amplitude modulation at the comb repetition rate has additionally been shown to improve microcomb stability [225] and hence the phase noise performance of the detected RF signal [9]. Additionally, synchronous pumping, with a relatively smallbandwidth pulse, of a fiber Fabry-Perot resonators has been exploited for spontaneous excitation of DKS microcombs [233].…”