Photonic integrated circuits suffer from a thermal drift of device performance, which is a key obstacle to the development of commercial optoelectronic products. Temperature-insensitive integrated waveguides and resonators have been demonstrated at a single wavelength, using materials with a negative TOC, which are not suitable for WDM devices and wideband nonlinear devices. Here, we propose two waveguides to realize the generation of broadband athermal features. For one of them, the temperature-insensitivity over a bandwidth of 780 nm (1280 to 2060 nm) with an ultra-small effective-TOC within is ±1×10<sup>-6</sup>/K. Uniquely, the waveguide has small anomalous dispersion (from 66 to 329 ps/nm/km) over the same band and is suitable for frequency comb generation without being affected by intra-cavity thermal dynamics. We also show another waveguide design with an effective-TOC variation of ±1×10<sup>-6</sup>/K over a bandwidth of 1060 nm, from 1220 to 2280 nm. The obtained dispersion varies from -232 to -502 ps/nm/km over the same band, which can be used in nonlinear devices.
Microresonator-based frequency combs have attracted a great deal of attention in recent years. Traditional generation scheme could be slow due to the operation of tunable lasers and thermal effects. In some spectral ranges, it is also difficult to find a tunable laser with a certain tuning range. In this paper, we propose a fast and simple method for Kerr comb generation without laser detuning and local cooling. In this way, the generation time can be reduced to tens of nanoseconds, three orders of magnitude faster.
Frequency comb generation in the mid-infrared (mid-IR)region is attractive recently. Here, we propose the Ge-on-Si microresonator for power-efficient frequency comb generation in the mid-IR. An octave-spanning comb can be obtained with power reduced to 190 mW. The robustness of the frequency comb generation with localized spectral loss is also analyzed. Based on the analysis, we propose a novel architecture of on-chip spectroscopy systems in the mid-IR.