Enhancement of self-phase modulation induced spectral broadening in silicon suspended membrane waveguides

We experimentally observed a possibly enhanced self-phase modulation (SPM) in silicon suspended membrane waveguides (SMWs) by measuring the spectral broadening of optical pulses. The nonlinear coefficient n ₂ and the two-photon absorption coefficient β ₂ of silicon SMWs were measured to be (4.6 ± 0.9) × 10⁻¹⁸ m² W⁻¹ and 0.46 cm GW⁻¹ at 1555 nm wavelength. We also proposed a method of using SPM-induced spectral broadening to obtain the coupling loss of a single grating coupler and experimentally compared the spectra of two grating couplers in silicon SMWs and in silicon-on-insulator waveguides. (paper)