Dispersion-Engineered SiN-Coated TeO₂ Hybrid Waveguide for Nonlinear Applications

On-chip light generation in the mid-infrared (mid-IR) region of the electromagnetic spectrum is gaining considerable attention due to its various potential applications in free-space communication, mid-IR spectroscopy, sensing, and thermal Imaging. In this work, we have designed a dispersion-engineered silicon nitride (SiN)-coated tellurium oxide (TeO₂) hybrid waveguide on silica (SiO₂) substrate with barium fluoride (BaF₂) as cladding for nonlinear applications. Strong modal confinement, broad dispersion characteristic, and high nonlinearity were achieved in the proposed hybrid waveguide design, which are important features for obtaining desired nonlinear applications. Through numerical simulations, we found that the dispersion curve is nearly flat within the dispersion range of −40.60 ps/nm/km to 33.15 ps/nm/km for a spectral bandwidth of 1.55–4.25 µm with a zero-dispersion wavelength (ZDW) around 1.80 µm, which is suitable for generating nonlinear effects such as four-wave mixing, self-phase modulation, and Raman scattering. Such types of on-chip hybrid waveguide devices can be pumped using a commercially available fiber laser operating at a wavelength of 2 µm. The design of the hybrid waveguide was optimized to achieve very low modal confinement loss ranging from 0.1 × 10⁻⁴ to 35 dB/cm, with a spectral bandwidth of 1.5–4 µm. Additionally, a high nonlinear coefficient value of 1372 W⁻¹ km⁻¹ was achieved at a pumping wavelength of 1.5 µm in hybrid waveguide. The results of such hybrid waveguides can be helpful to experimentalists working in this field for developing nonlinear hybrid waveguide devices. These nonlinear hybrid waveguide devices have potential nonlinear applications, including four-wave mixing, Raman scattering, and supercontinuum spectrum spanning the near-IR to mid-IR. Further, the on-chip hybrid waveguide structure can be significantly help to expand the functionality of future photonics integrated circuits.