Slot Waveguides With Silicon-Rich Materials for Nonlinear Applications

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 \sim2.2 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_3N_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.