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Dynamic thermal emission control has attracted growing interest in a broad range of fields including radiative cooling, thermophotovoltaics and adaptive camouflage. Previous demonstrations of dynamic thermal emission control present disadvantages of either large thickness or requiring sustained electrical or thermal excitations. In this paper, an ultrathin plasmonic thermal emitter incorporating zero‐static‐power phase‐changing material Ge2Sb2Te5 (GST) is experimentally demonstrated to dynamically control thermal emission. The whole structure shows a total thickness of 550 nm (∼0.023λ), which is well below the subwavelength scale. (Picture: Yurui Qu et al., article number 1700091, in this issue)

We report a type of quasi-phase-matched (QPM) Cerenkov third-harmonic generation (CTHG) in a periodic-poled LiTaO₃ waveguide. The CTHG results from a guided-to-guided second-harmonic generation cascaded with a guided-to-radiated sum-frequency generation (SFG) in the waveguide. In the guided-to-radiated SFG process, nonlinear interactions with participating and nonparticipating reciprocal vectors would lead to different CTHG radiations. In addition, the power and temperature detuning characters of QPM CTHG were studied. Theoretical predictions were in good agreement with experimental results.

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