Broadband and ultrafast graphene-based integrated photonics

Abstract

We review our recent progress on graphene integrated photonics for next generation optical communications. We present the design principles of graphene photodetectors and optical modulators as well as recent results on Si and SiN photonic platforms. We show optical modulators at communication wavelengths with electro-optical bandwidth up to 30GHz and operation at 50Gb/s on-off keying (OOK). We report on very recent progress about graphene photodetectors with ultra-high bandwidth (>67GHz) based on the photo-thermo-electric (PTE) effect. The last is of particular interest as it enables a zero dark-current direct conversion of the optical signal into a voltage which can be amplified by a voltage pre-amplifier rather than a transimpedance amplifier (TIA). This is a potential breakthrough in scaling the bandwidth of photoreceiver towards increasing bandwidths, as the TIA imposes strict trade-offs between gain and bandwidth. With the proposed device we show direct detection of optical signals exceeding 100Gb/s in a voltage detection scheme without dark current bias.