Kerr Nonlinear Optical Signal Processing in Ultra-silicon-rich Nitride- based Devices

Nonlinear photonics devices are designed and fabricated on bandgap engineered ultra-silicon-rich nitride (USRN). The USRN films are compositionally engineered to possess a bandgap of 2.1 eV to eliminate two-photon absorption at 1.55 μm while maintaining a large linear and nonlinear refractive index of 3.1 and 2.8 × 10^-13 cm²/ W respectively. We present nanopho-tonic devices periodic in one and two dimensions that introduce an engineered group index profile. The devices are designed to possess a specific dispersion profile that enables slow-light behavior and augmented waveguide nonlinear parameters to be observed. Photonic crystal waveguides with flat band region engineered at the 1.55 μm region show a ×40 enhancement increase in the nonlinear parameter, providing an effective nonlinear parameter of 1.97 × 10⁴ W^-l/m. One-dimensional photonic crystals are designed with effective index modulation effected in the device cladding, and demonstrated to exhibit augmented anomalous dispersion on the band edge while maintaining high transmission. Consequently, the reduced dispersive length combined with the large intrinsic nonlinearity in the material enables time and spectrally resolved characterizations of soliton formation, temporal compression and soliton fission to be experimentally observed. This represents one of the first observations of Bragg solitons on a chip, with the largest soliton-effect pulse compression to date with a compression factor of × 4.