Ultrafast Thermal Switching Enabled by Transient Polaritons

Ultrafast thermal switches are pivotal for managing heat generated in advanced solid-state applications, including high-speed chiplets, thermo-optical modulators, and on-chip lasers. However, conventional phonon-based switches cannot meet the demand for picosecond-level response times, and existing near-field radiative thermal switches face challenges in efficiently modulating heat transfer across vacuum gaps. To overcome these limitations, we propose an ultrafast thermal switch design based on pump-driven transient polaritons in asymmetric terminals. Demonstrated with WSe₂ and graphene, this approach achieves an impressive thermal switching ratio exceeding 10,000 with response times on the picosecond scale, outperforming current designs by at least 2 orders of magnitude. This exceptional performance is driven by dynamic polaritonic coupling between terminals, activated by ultrafast photoexcitation. Additionally, the WSe₂ monolayer-based switch exhibits a laser cooling effect, enabled by enhanced carrier excitation efficiency and prolonged carrier lifetimes, introducing a disruptive mechanism for laser cooling. Our findings highlight the strong potential of photodriven transient polaritons in advancing ultrafast thermal switches and nanoscale cooling technologies.