On the numerical modeling of optical-switching in non-linear phase-shifted grating

We discuss the transmission properties of non-linear phase-shifted grating. Using a direct integration method, we show that phase-shift in linear sinusoidal grating introduces a very narrow resonance in the band gap with very high amplification factor. Using frequency in the vicinity of this resonance, we show that the threshold of switching can be reduced significantly. Based on the direct integration method, it is shown that Coupled-Mode Theory may produce inaccurate results for the case of both linear and non-linear grating structure with and without phase-shift.