title: Thermal tuning of Kerr frequency combs in silicon nitride microring resonators.
abstract: Microresonator based Kerr frequency comb generation has many attractive features, including ultrabroad spectra, chip-level integration, and low power consumption. Achieving precise tuning control over the comb frequencies will be important for a number of practical applications, but has been little explored for microresonator combs. In this paper, we characterize the thermal tuning of a coherent Kerr frequency comb generated from an on-chip silicon nitride microring. When the microring temperature is changed by ~70 °C with an integrated microheater, the line spacing and center frequency of the comb are tuned respectively by -253 MHz (-3.57 MHz/°C) and by -175 GHz (-2.63 GHz/°C); the latter constitutes 75% of the comb line spacing. From these results we obtain a shift of 25 GHz (362.07 MHz/°C) in the comb carrier-envelope offset frequency. Numerical simulations are performed by taking into account the thermo-optic effects in the waveguide core and cladding. The temperature variation of the comb line spacing predicted from simulations is close to that observed in experiments. The time-dependent thermal response of the microheater based tuning scheme is characterized; time constants of 30.9 μs and 0.71 ms are observed.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Xue
authors.forename: Yi
authors.initials: Y
authors.lastname: Xuan
authors.forename: Cong
authors.initials: C
authors.lastname: Wang
authors.forename: Pei-Hsun
authors.initials: PH
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Ben
authors.initials: B
authors.lastname: Niu
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Leaird
authors.forename: Minghao
authors.initials: M
authors.lastname: Qi
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Weiner