Four-wave mixing in silicon wire waveguides

TLDR

The nonlinear refractive index in silicon wire waveguides can cause significant crosstalk in dense wavelength division multiplexing systems. The high nonlinearity arises from the extremely small core of silicon wire waveguides. We observed four‑wave mixing in silicon wire waveguides at telecom‑band powers, achieving a maximum conversion efficiency of –35 dB in a 1.58‑cm device, a nonlinear index of 9 × 10⁻¹⁸ m²/W, and demonstrating 10‑Gbps wavelength conversion in a 5.8‑cm waveguide, indicating that longer low‑loss waveguides could enable practical silicon‑based wavelength conversion.

Abstract

We report the observation of four-wave mixing phenomenon in a simple silicon wire waveguide at the optical powers normally employed in communications systems. The maximum conversion efficiency is about -35 dB in the case of a 1.58-cm-long silicon wire waveguide. The nonlinear refractive index coefficient is found to be 9x10-18 m2/W. This value is not negligible for dense wavelength division multiplexing components, because it predicts the possibility of large crosstalk. On the other hand, with longer waveguide lengths with smaller propagation loss, it would be possible to utilize just a simple silicon wire for practical wavelength conversion. We demonstrate the wavelength conversion for data rate of 10-Gbps using a 5.8-cm-long silicon wire. These characteristics are attributed to the extremely small core of silicon wire waveguides.