Slot Waveguides With Silicon-Rich Materials for Nonlinear Applications

Abstract

Slot waveguides based on silicon-rich materials are proposed and experimentally demonstrated, which consist of a silicon-rich oxide (SRO) slot layer sandwiched by two silicon-rich nitride (SRN) layers. Measurements show the waveguides have a low propagation loss of $\sim$2.2 dB/cm and a 50-$\mu \text{m}$-radius micro-ring resonator can achieve a loaded quality factor ($Q_{load}$) of $\sim 10^5$. Four-wave mixing experiments in the slot waveguides reveal a high nonlinearity $\gamma$ of 16 W$^{-1}$m$^{-1}$ of the waveguide and an averaged nonlinear index $n_2$ of 2.5 x 10$^{-18}$ m $^2$/W of the silicon-rich materials, 10 times larger than that of stoichiometric silicon nitride (Si$_3$N$_4$). Supercontinuum generation (SCG) experiments have shown a large fabrication tolerance of such slot waveguides that 1.2 octave spectral broadening in a 1510-nm-wide slot waveguide can be achieved while that is 0.9 octave in a slot waveguide with a width shrinking as large as 220 nm.

Keywords

• Integrated optics
• nonlinear photonics
• supercontinuum generation
• four-wave mixing