Enhanced optical nonlinearities in CMOS-compatible ultra-silicon-rich nitride photonic crystal waveguides

We present the design, fabrication, and characterization of photonic crystal waveguides (PhCWs) on an ultra-silicon-rich nitride (USRN) platform, with the goal of augmenting the optical nonlinearities. The design goals are to achieve an optimized group index curve on the PhCW band edge with a non-membrane PhCW with symmetric SiO2 undercladding and overcladding, so as to maintain back-end CMOS compatibility and better structural robustness. Linear optical characterization, as well as non-linear optical characterization of PhCWs on ultra-silicon-rich nitride is performed at the telecommunication wavelengths. USRN's negligible two-photon absorption and free carrier losses at the telecommunication wavelengths ensure that there is no scaling of two-photon related losses with the group index, thus maintaining a high nonlinear efficiency. Self-phase modulation experiments are performed using a 96.6 mu m PhCW. A 1.5 pi phase shift is achieved with an input peak power of 2.5W implying an effective nonlinear parameter of 1.97 x 10(4) (W m)(-1). This nonlinear parameter represents a 49 x enhancement in the nonlinear parameter from the slow light effect, in good agreement with expected scaling from the measured group index. Published by AIP Publishing.