Electron-wave-stimulated mid-infrared emission from graphene-substrate quantum oscillators

Abstract

Generating tunable, high-intensity mid-infrared (MIR) to terahertz (THz) radiation on-chip remains a formidable challenge due to the rigid spectral limits of conventional thermal emitters. While graphene has emerged as a promising platform for light-matter interaction, active control of its radiative properties has been largely confined to surface-limited phenomena mostly associated with plasmons. Here, we introduce a new MIR radiation platform where multi-layer chemical vapor deposition (CVD) graphene is integrated with modular, vibrationally active dielectric substrates, ranging from organic thin films and inorganic matrices. A pivotal discovery is that the long-range de Broglie wavelength of drift carriers enables coherent coupling with vibrational transition dipoles deep within the substrate bulk. This transforms the substrate into a three-dimensional volume emission source, where complex spectra of characteristic molecular and lattice vibration energies are additively combined on demand. The exponential scaling of radiation intensity appears when the electrons' drift velocity in graphene exceeds the sound velocity of the substrates, consistent with quantum stimulated amplification associated with Cerenkov electron-phonon instability. Our work redefines the passive dielectric substrate as an active, programmable component driven by electron waves, paving the way for next-generation system-on-a-chip MIR-THz photonics, environmental and biomedical sensing, and highly efficient mode-specific electrothermal applications.