paper

Deep and fast free-space electro-absorption modulation in a mobility-independent graphene-loaded Bragg resonator

arXiv:1805.05472 · doi:10.1063/1.5030699

Abstract

Deep and fast electro-optic modulation is critical for high-speed near infrared signal processing. We combine the electro-absorption tunability of graphene with the high-Q resonance of a Bragg-based Fabry-Perot resonator at λ=1550 nm and show that ~100% free-space signal modulation (>50 dB extinction ratio, <1 dB insertion loss) at high speed (>1 GHz) can always be achieved independently of graphene quality (mobility), provided the device is operating in reflection mode and tuned in critical coupling with graphene. Remarkably, the critical coupling mechanism produces a higher extinction ratio for lower graphene mobility. We use practical considerations to optimize the device architecture and operation as a function of graphene mobility. With a small modification this scheme can be turned into a very sensitive acousto-absorption modulator with a ~30 dB/Å extinction ratio, or an index sensor with 10^7 %/RIU sensitivity. These designs can be easily extended throughout the midIR spectrum by appropriate scaling of layer thicknesses.

arXiv comment6 pages, 4 figures

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