MoS 2 is a layered quasi-2D material that can enhance effective third-order optical nonlinearity of waveguides. In this paper, we measured the optical loss of MoS 2 on silicon waveguides and compared the conversion efficiencies of four-wave mixing (FWM) in silicon waveguides with and without MoS 2 on the top cladding. Hybrid integration of the few-layer MoS 2 produced about 4 dB enhancement in the idler output of FWM. The Kerr coefficient of MoS 2 was obtained as (2.7±0.2)×10 −16 m 2 W −1 . The refractive index of MoS 2 was obtained from the characteristics of grating couplers.

Integrated Raman lasers have been well explored using silica and silicon platforms for decades. A well‐known equation with negligible nonlinear losses is employed for predictions of Raman lasing threshold powers in critically coupled cavities. However, nonlinear losses are known to be highly detrimental to silicon devices. Herein, for the first time, including the effects of linear loss, nonlinear losses, and cavity design, a new general equation that predicts the onset of Raman lasing in a cavity is derived and validated experimentally. Generally, a cavity with a small effective area, a short length, and high quality factors (Qs) at both pump and Stokes wavelengths can lase at relatively low pump power. This theory is verified by the experimental results with sub‐milliwatt threshold powers in 2.8 mm long multimode cavities with different Qs at different pump wavelengths. The derived Raman gain coefficients from the measurements follow the scaling rules of Raman gain. This work advances the understanding of Raman lasing in high‐Q multimode cavities. It also shows that Raman lasing at O/S‐band is possible in racetrack resonators without needing any reverse bias and the broad operation wavelength is promising for single‐chip silicon devices operating at all communication bands.

Multimode silicon resonators with ultralow propagation losses for ultrahigh quality (Q) factors have been attracting attention recently. However, conventional multimode silicon resonators only have high Q factors at certain wavelengths because the Q factors are reduced at wavelengths where fundamental modes and higher-order modes are both near resonances. Here, by implementing a broadband pulley directional coupler and concentric racetracks, we present a broadband high-Q multimode silicon resonator with average loaded Q factors of 1.4 × 106 over a wavelength range of 440 nm (1240–1680 nm). The mutual coupling between the two multimode racetracks can lead to two supermodes that mitigate the reduction in Q factors caused by the mode coupling of the higher-order modes. Based on the broadband high-Q multimode resonator, we experimentally demonstrated a broadly tunable Raman silicon laser with over 516 nm wavelength tuning range (1325–1841 nm), a threshold power of (0.4 ± 0.1) mW and a slope efficiency of (8.5 ± 1.5) % at 25 V reverse bias.

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We experimentally observed a possibly enhanced self-phase modulation (SPM) in silicon suspended membrane waveguides (SMWs) by measuring the spectral broadening of optical pulses. The nonlinear coefficient n2 and the two-photon absorption coefficient β2 of silicon SMWs were measured to be (4.6 ± 0.9) × 10−18 m2 W−1 and 0.46 cm GW−1 at 1555 nm wavelength. We also proposed a method of using SPM-induced spectral broadening to obtain the coupling loss of a single grating coupler and experimentally compared the spectra of two grating couplers in silicon SMWs and in silicon-on-insulator waveguides.