Zero-biased graphene photodetector with high responsivity integrated into silicon microring resonator

This study presents a dual-core graphene-based waveguide photodetector integrated into a silicon microring resonator to achieve enhanced responsivity. The proposed photodetector operates under zero-bias condition and employs two independent graphene gates to electrostatically induce a pn junction along the graphene channel. Maximum light absorption occurs at the critical coupling point, with a graphene length of 7 μm embedded into the silicon waveguide. The responsivity, bandwidth, and noise equivalent power of 230 V/W, 17.6 GHz, and 43.3 pW/Hz^0.5, respectively, are obtained at λ = 1550 nm. Calculating voltage responsivity instead of current responsivity in the photodetector eliminates the need for transimpedance amplification. Zero-bias operation, low power consumption, and improved voltage responsivity make the proposed structure highly suitable for various telecommunication applications, such as data transmission, military, and industrial applications with high precision. Here, the finite difference eigenmode and the finite difference time domain methods are used to calculate the propagation mode profile and to perform optical simulations, respectively. Also, the performance metrics of the photodetector are calculated using thermal equations. The feasibility of the proposed photodetector has been validated according to experimentally demonstrated graphene photodetectors. Thus, the calculated results are reliable and practically achievable.