Abstract

Titanium dioxide (TiO₂) are foreseen as one of the promising material platforms for highly efficient on-chip signal processing, due to its CMOS-compatibility, broad transparency window from visible to mid-infrared wavelengths, relatively large linear and nonlinear indices as well as having a two-photon-absorption-free bandgap at wavelengths around 1550 nm [1-4]. So far, supercontinuum generation [1], Raman scattering [2], and third harmonic generation [3] have been demonstrated in TiO₂ waveguides. Wavelength conversion is one of the basic functionalities within nonlinear optics and has been widely applied for optical signal processing. Recently, we have presented four-wave mixing (FWM) experiments within a straight TiO₂ photonic waveguide and demonstrated a wavelength conversion efficiency (CE) of -36.2 dB with a coupled pump power of ~20 dBm [4]. The CEs can be pronouncedly enhanced by utilizing a micro-ring resonator (MRR) [5]. Here, we present FWM experiments in a TiO₂ MRR having a high intrinsic Q-value of ~1.5 × 10⁵ and achieve an idler power enhancement of 18.6 dB on resonance comparing to the off resonance case.

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