Analysis and Applications of Reflection-Spectrum Envelopes for Sampled Gratings

In this paper, an analytical method is proposed for calculating reflection-spectrum envelopes (RSEs) of various multipeak gratings. Consequently, impacts of parameters on the envelope of the sampled grating are analyzed in detail both with and without refractive index variation. Accuracy of those proposed methods has been verified by the good agreement with the simulated reflectivity spectrum of the transfer matrix method. A technology of multiple reflection spectrum envelopes concatenation (MRSEC) is proposed to design multipeak gratings with broad flat-top spectrum envelopes: one is the digital concatenated grating; the other is the consecutive interleaved sampled grating. The proposed technology can densify spectral channels of sampled gratings with fixed reflectivity peak space, as well as spatially physical corrugation of structure.