Enhancing Optical Nonlinearity in a Nonstoichiometric SiN Waveguide for Cross-Wavelength All-Optical Data Processing

Nonstoichiometric SiN x with enhancing optical nonlinearity is enabled to facilitate the waveguide microring resonator for cross-wavelength all-optical data processing applications. The Si/N composition ratio of the nonstoichiometric SiN x can be detuned from stoichiometric to Si-rich by adjusting the SiH 4 /NH 3 fluence ratios. Under pumping with incoming pulsed data, the comb-like transmittance of the nonstoichiometric SiN x microring resonator can spectrally red-shift by 100 pm as its effective refractive index changed by more than 1 order of magnitude due to the enhanced nonlinear Kerr effect. The enlarged refractive index of Δ n = 1.6 × 10 –4 with increasing nonlinear refractive index to n 2 = 1.6 × 10 –13 cm 2 /W at 1550 nm is observed at a Si concentration of 66.2% in the Si-rich SiN x film. In application, a cross-wavelength all-optical data conversion/inversion processor based on the nonstoichiometric SiN x microring resonator is presented. The dense nanoscale Si content formed by a higher Si/N composition ratio of the SiN x contributes to an enhanced Kerr effect based optical nonlinear switching, which enables the optimized 12 Gbit/s all-optical conversion of the pulsed return-to-zero on–off-keying (RZ-OOK) data with converted or inverted format. The photon lifetime of ∼19 ps in the Si-rich SiN x microring resonator cavity can support the Si-rich SiN x all-optical Kerr switch with a maximal bandwidth of up to 50 GHz.