Enhancing SiN waveguide optical nonlinearity via hybrid GaS integration

Abstract

Silicon nitride (SiN) has been demonstrated as an exceptional low-loss platform for integrated photonics, however, its relatively small nonlinear refractive index limits its full potential in applications such as all-optical phase modulation, supercontinuum generation, and frequency combs. Here, we demonstrate that through hybrid integration with wide-bandgap 2D materials such as gallium sulfide (GaS), the nonlinear refractive index of the hybrid waveguide can be greatly increased (by five-fold in our experiment). We fabricate high quality factor SiN/GaS microring resonators, with low two-photon absorption at telecom wavelengths, to demonstrate enhanced all-optical modulation. We show that the hybrid platform is suitable for assessing the nonlinear properties of 2D materials, and we have used it to quantify, for the first time, the nonlinear refractive index (n 2) of GaS. For GaS, n 2 = 12 × 10 − 19 m 2 W − 1 , which is ten times larger than that of SiN.

Ultrafast Nonlinear Optical Response and Carrier Dynamics in Layered Gallium Sulfide (GaS) Single-Crystalline Thin Films

“…Their results show that GaS has fascinating properties that could be used in transistors, LEDs, photodetectors, catalysts, etc (Late et al, 2012;Hu et al, 2013;Harvey et al, 2015;Jung et al, 2015;Lu et al, 2020;Tverjanovich et al, 2020;Zappia et al, 2021). Despite these efforts, however, few reports are available in literature about the nonlinear optical (NLO) properties of GaS (Allakhverdiev et al, 1997;Kato and Umemura, 2011;Isik et al, 2013;Karatay, 2019;Deckoff-Jones et al, 2021;Xu et al, 2021). And pervious results on NLO response of GaS were carried out with picosecond (ps), nanosecond (ns) and continuous wave (CW) laser (Isik et al, 2013;Karatay, 2019;Xu et al, 2021).…”

Enhancing Si3N4 Waveguide Nonlinearity with Heterogeneous Integration of Few-Layer WS2

“…Enhancements of FWM efficiency up to 7.3 dB in a SiN waveguide integrated with graphene oxide and 4 dB in a silicon waveguide integrated with MoS 2 have been successfully demonstrated. Recently, the heterogeneous integration of GaS thin-flakes with SiN microring resonators has been demonstrated, showing a 5-fold improvement of Kerr coefficient. In comparison to the aforementioned 2D materials, WS 2 has an intriguing combination of optical properties, including good transparency and a strong nonlinearity in the near-infrared wavelength range, making it a potential choice for on-chip nonlinear optics, especially in the conventional telecom windows at ∼1.5 μm. ,, …”