Inverse design of the multimode Bragg grating based on time-domain layer peeling method

Abstract

Multimode waveguide Bragg gratings filters with square shape amplitude responses and well-controlled dispersion characteristics are achieved by the Time-Domain Layer Peeling method for the first time, the Bragg grating structures can be mapped by the complementary lateral-misalignment modulation apodization. Three filters with different amplitude and phase responses are demonstrated. For the dispersion-less filter, the dispersion compensation filter and the three-channel dispersionless filter, the 3 dB bandwidth and the group delay of the realizable spectral responses are 4.0 nm, 4.7 nm, 2.1 nm and 0 ps/nm, 5.7 ps/nm, 0 ps/nm, the group delay ripples have a standard deviation of 1.7 ps, 1.5 ps, and 2.0 ps. The multimode relaxes the fabrication requirement in terms of both the lithography resolution and minimum feature size/spacing while maintaining the advantages of low insertion loss.