Photoemission plays a central role in a wide range of fields, from electronic structure measurements to free-electron laser sources. In metallic emitters, single-photon¹, multiphoton^2,3,4,5 or strong-field emission^6,7,8,9,10 processes are the primary photoemission mechanisms. Here, using a sub-work-function 3.06 eV continuous-wave laser, photoemission from waveguide-integrated monolayer graphene is observed to occur at peak power densities >5 orders of magnitude lower than reported multiphoton and strong-field emission^6,11,12. The behaviour is explained by the emission of hot electrons in graphene. In monolayer graphene, the need for photoelectrons to be transported to an emitting surface is eliminated, dramatically enhancing the probability of emission before thermalization. These results indicate that integrated-photonics-driven hot-electron emission provides a rich new area of exploration for both electron emission and integrated photonics.

从电子结构测量到自由电子激光源，光发射在许多领域都发挥着核心作用。在金属发射器中，单光子¹，多光子^{2、3、4、5}或强场发射^{6、7、8、9、10}过程是主要的光发射机制。在这里，使用子功函数3.06 eV连续波激光器，观察到波导集成单层石墨烯的光发射发生在峰值功率密度> 5个数量级，且比报告的多光子和强场发射^{低6,5,11,12。}。该行为可以通过石墨烯中热电子的发射来解释。在单层石墨烯中，消除了将光电子传输到发射表面的需要，从而大大提高了在热化之前发射光的可能性。这些结果表明，集成光子驱动的热电子发射为电子发射和集成光子学提供了丰富的探索新领域。