High-Responsivity Graphene-Boron Nitride Photodetector and Autocorrelator in a Silicon Photonic Integrated Circuit

TL;DR

This paper presents an on-chip ultrafast graphene-boron nitride photodetector integrated with silicon photonics, demonstrating high responsivity, gigahertz bandwidth, and nonlinear optical capabilities for autocorrelation at low power levels.

Contribution

The work introduces a novel 2D heterostructure photodetector integrated in silicon photonics, achieving high-speed, high-responsivity, and nonlinear optical functionalities for on-chip applications.

Findings

Maximum responsivity of 0.36 A/W

3 dB bandwidth of 42 GHz

Effective autocorrelation with picosecond resolution

Abstract

Graphene and other two-dimensional (2D) materials have emerged as promising materials for broadband and ultrafast photodetection and optical modulation. These optoelectronic capabilities can augment complementary metal-oxide-semiconductor (CMOS) devices for high-speed and low-power optical interconnects. Here, we demonstrate an on-chip ultrafast photodetector based on a two-dimensional heterostructure consisting of high-quality graphene encapsulated in hexagonal boron nitride. Coupled to the optical mode of a silicon waveguide, this 2D heterostructure-based photodetector exhibits a maximum responsivity of 0.36 A/W and high-speed operation with a 3 dB cut-off at 42 GHz. From photocurrent measurements as a function of the top-gate and source-drain voltages, we conclude that the photoresponse is consistent with hot electron mediated effects. At moderate peak powers above 50 mW, we observe a saturating photocurrent consistent with the mechanisms of electron-phonon supercollision cooling. This nonlinear photoresponse enables optical on-chip autocorrelation measurements with picosecond-scale timing resolution and exceptionally low peak powers.