Theory for Effective Advection Effect: Spatiotemporal Modulation

Abstract

In this chapter, we introduce spatiotemporal modulation to realize thermal wave nonreciprocity. The major mechanism is the effective advection effect of spatiotemporal modulation in an open thermal system. We further analyze the phase difference between two spatiotemporally modulated parameters, which offers a tunable parameter to control nonreciprocity. We further define a rectification ratio based on the reciprocal of spatial decay rates and discuss the nonreciprocity conditions accordingly. Finite-element simulations are performed to confirm theoretical predictions, and experimental suggestions are provided to ensure the feasibility of spatiotemporal modulation. These results have potential applications in realizing thermal detection and thermal stabilization simultaneously.