Graphene-Assisted Polarization-Insensitive Electro-absorption Optical Modulator

Abstract

We report on a polarization-insensitive optical modulator architecture comprised of silica/Si/hBN/graphene/hBN/ graphene/hBN/Si stack upon a silica substrate to support transverse electric (TE) and transverse magnetic (TM) polarizing modes with identical absorption. The identical absorption between TE and TM modes is strict condition for realizing polarization-insensitive electro-absorption optical modulator. This in turn entails significant compromise in polarization-sensitivity loss. The horizontal arm of active region of waveguide support TE mode while TM mode is supported by vertical arm ensuring polarization-sensitive loss of <; 1 dB. The model is capable of offering extinction ratio of 18.87 dB, insertion loss of 2.32 dB and figure-of-merit of 8.14 for TE mode. Concurrently, for TM mode are 19.39 dB, 2.41 dB and 8.04. The operating wavelength of modulator ranges from ~ 1500 to ~ 1590 nm with optical bandwidth excess of 90 nm. The 3-dB modulation bandwidth of 62.74 GHz is realized with active length of 12 μm long at the expense of 1.28 fJ/bit ensuring the polarizationsensitive loss at ON-State of 0.1 dB and tolerance between TE and TM modes of 0.82 dB.