Numerical modeling and analysis of a TM mode-division (de)multiplexer based on grating assisted couplers

Abstract

In this paper, a mode-division (de)multiplexer capable of multiplexing three transverse magnetic modes simultaneously at the operating wavelength of 1550 nm has been proposed. The device structure is designed using slab waveguides with Si and SiO2 as core and cladding materials, respectively. Grating assisted couplers have been employed to couple the fundamental modes of two single-mode waveguides with the two higher-order modes of a multimode waveguide in the opposite direction. The fundamental mode of the multimode waveguide keeps propagating in the same waveguide without any power coupling to other modes. Using perturbation approach and coupled-mode theory, the proposed structure is theoretically analyzed. 2D Finite Difference Time Domain numerical simulation technique has been used to simulate and analyze the proposed mode division (de)multiplexer. During the demultiplexing operation, the proposed device exhibits insertion loss ranging from − 2.01 to − 0.01 dB, return loss ranging from − 31.07 to − 9.17 dB, and crosstalk in the range of − 41.76 to − 13.58 dB. Whereas for the multiplexing operation, insertion loss, return loss, and crosstalk range from − 1.59 to − 0.01 dB, − 31.07 to − 10.17 dB, and − 41.76 to − 8.05 dB respectively.