A High‐Performance Waveguide‐Integrated Large‐Angle Twisted Bilayer Graphene Bolometer

Graphene photodetectors have the advantages of excellent CMOS compatibility and high bandwidths up to sub‐THz, providing a promising option for photodetection on silicon. As a representative type of photodetector, graphene bolometers exhibit high responsivity, but still have notable limitations in sensitivity and linearity. In this work, a waveguide‐integrated bolometer utilizing large‐angle twisted bilayer graphene (LA‐TBG) is demonstrated for the first time, achieving unprecedented overall performances with 109 pW Hz −1/2 NEP and 0.48 A W −1 responsivity even with optical power as high as 4.6 mW, along with a 3dB‐bandwidth of >67 GHz at 1.55 µm and successful reception of 120 Gbps non‐return‐to‐zero signals. This device significantly alleviates the intrinsic linearity issue of graphene bolometers, showcasing superior responsivity and sensitivity in a large dynamic range of input optical power. A comprehensive photobolometric model is established to evaluate device performance metrics and theoretically probe the hypothesized enhancement of photobolometric response via suppressed electronic thermal conductivity in TBG. This work greatly promotes graphene bolometers to be monolithically integrated with silicon photonic chips for applications of new‐band optical communications, optical sensing and optoelectronic mixing.