High-responsivity graphene photodetectors integrated on silicon microring resonators

Abstract

Graphene integrated photonics provides several advantages over conventional Si photonics. Single layer graphene (SLG) enables fast, broadband, and energy-efficient electro-optic modulators, optical switches and photodetectors (GPDs), and is compatible with any optical waveguide. The last major barrier to SLG-based optical receivers lies in the current GPDs' low responsivity when compared to conventional PDs. Here we overcome this by integrating a photo-thermoelectric GPD with a Si microring resonator. Under critical coupling, we achieve>90% light absorption in a similar to 6 mu m SLG channel along a Si waveguide. Cavity-enhanced light-matter interactions cause carriers in SLG to reach similar to 400 K for an input power similar to 0.6 mW, resulting in a voltage responsivity similar to 90 V/W, with a receiver sensitivity enabling our GPDs to operate at a 10(-9) bit-error rate, on par with mature semiconductor technology, but with a natural generation of a voltage, rather than a current, thus removing the need for transimpedance amplification, with a reduction of energy-per-bit, cost, and foot-print. Optical receivers based on graphene still suffer from low responsivity. Here, the authors integrate a photo-thermoelectric graphene photodetector with a Si micro-ring resonator, and obtain a voltage responsivity similar to 90 V/W and a reduction of energy-per-bit consumption, enabling performance on par with mature semiconductor technology.