Broadband mid-infrared graphene bolometer

High detection speed, large responsivity, and room-temperature operation are crucial for modern mid-infrared bolometers. The low electronic heat capacity and weak electron-phonon coupling make graphene a remarkable candidate for fast broadband bolometer at room temperature. However, the weak temperature-dependent electrical transport in graphene hinders its applications. Here, we demonstrate ultra-broadband infrared graphene bolometers enabled by the large temperature coefficient of resistance and weak electron-phonon coupling in the intrinsic graphene. Our device has an ultra-broadband photoresponse from 1.3 to 12.2 μm with decent external responsivities at room temperature. Our results show the application potential of pristine graphene in high-speed broadband mid-infrared photodetection. Furthermore, we show that its integration with infrared waveguides, photonic crystals, and plasmonic cavities can significantly improve the performance.