Suppression of multiple photon absorption in a SiC photonic crystal nanocavity operating at 1.55 μm

We show that a SiC photonic crystal cannot only inhibit two photon absorption completely, but also suppress higher-order multiple photon absorption significantly at telecommunication wavelengths, compared to conventional Si-based photonic crystal nanocavities. Resonant spectra of a SiC nanocavity maintain a Lorentzian profile even at input energies 100 times higher than what can be applied to a Si nanocavity without causing nonlinear effects. Theoretical fitting of the results indicates that the four photon absorption coefficient in the SiC nanocavity is less than 2.0 × 10^-5 cm ⁵/GW³. These results will contribute to the development of high-power applications of SiC nanocavities such as harmonic generation, parametric down conversion, and Raman amplification.