Performance of SOI Bragg Grating Ring Resonator for Nonlinear Sensing Applications

In this paper, a resonant sensor formed by a silicon-on-insulator waveguiding Bragg grating ring resonator working in linear and non-linear regime is proposed. In linear regime, the device shows a spectral response characterized by a photonic band gap (PBG). Very close to the band gap edges, it exhibits split resonant modes having a splitting magnitude equal to the PBG spectral extension, which is almost insensitive to the fabrication tolerances. When the device operates in nonlinear regime, exactly in that spectral region showing the split resonant mode structure, the sensing performance is strongly improved. This improvement has been demonstrated through a detailed model based on a set of full-vectorial equations taking into account not only all non-linear effects excited in the integrated silicon structure (i.e. Two Photon Absorption (TPA), TPA-induced Free Carrier Absorption, plasma dispersion, Self-Phase-Modulation and Cross-Phase-Modulation effects as induced by Kerr nonlinearity), but also the deleterious thermal and stress effects affecting the sensor performance.