High sensitivity, fast response time and strong light absorption are the most important metrics for infrared sensing and imaging. The trade-off between these characteristics remains the primary challenge in bolometry. Graphene with its unique combination of a record small electronic heat capacity and a weak electron–phonon coupling has emerged as a sensitive bolometric medium that allows for high intrinsic bandwidths^1–3. Moreover, the material’s light absorption can be enhanced to near unity by integration into photonic structures. Here, we introduce an integrated hot-electron bolometer based on Johnson noise readout of electrons in ultra-clean hexagonal-boron-nitride-encapsulated graphene, which is critically coupled to incident radiation through a photonic nanocavity with Q = 900. The device operates at telecom wavelengths and shows an enhanced bolometric response at charge neutrality. At 5 K, we obtain a noise equivalent power of about 10 pW Hz^–1/2, a record fast thermal relaxation time, <35 ps, and an improved light absorption. However the device can operate even above 300 K with reduced sensitivity. We work out the performance mechanisms and limits of the graphene bolometer and give important insights towards the potential development of practical applications.

高灵敏度，快速响应时间和强光吸收是红外传感和成像的最重要指标。这些特性之间的权衡仍然是辐射热分析的主要挑战。石墨烯以其创纪录的小电子热容量和弱的电子-声子耦合的独特组合，已成为一种敏感的辐射热测量介质，可实现较高的固有带宽^1-3。此外，通过集成到光子结构中，可以将材料的光吸收增强到接近统一。在此，我们介绍一种基于超净六方氮化硼氮化硼包裹的石墨烯中电子的约翰逊噪声读数的集成热电子辐射热计，该热电子辐射热计通过具有Q值的光子纳米腔与入射辐射临界耦合 =900。该设备在电信波长下工作，并且在电荷中性时显示出增强的辐射热响应。在5 K时，我们获得约10 pW Hz ^{– 1/2}的噪声等效功率，创纪录的快速热弛豫时间<35 ps，并改善了光吸收。但是，该设备甚至可以在300 K以上的环境下以较低的灵敏度工作。我们研究了石墨烯辐射热测量仪的性能机制和局限性，并为实际应用的潜在发展提供了重要见解。