Perfect energy-feeding into strongly coupled systems and interferometric control of polariton absorption

Abstract

The ability to feed energy into a system, or -equivalently -to drive that system with an external input is a fundamental aspect of light-matter interaction. The key concept in many photonic applications is the "critical coupling" condition [1,2]: at criticality, all the energy fed to the system via an input channel is dissipated within the system itself. Although this idea was crucial to enhance the efficiency of many devices, it was never considered in the context of systems operating in a non-perturbative regime. In this so-called strong coupling regime, the matter and light degrees of freedom are in fact mixed into dressed states, leading to new eigenstates called polaritons [3-10].Here we demonstrate that the strong coupling regime and the critical coupling condition can indeed coexist; in this situation, which we term strong critical coupling, all the incoming energy is converted into polaritons. A semiclassical theory -equivalently applicable to acoustics or mechanics -reveals that the strong critical coupling corresponds to a special curve in the phase diagram of the coupled light-matter oscillators. In the more general case of a system radiating via two scattering ports, the phenomenology displayed is that of coherent perfect absorption (CPA) [11,12], which is then naturally understood and described in the framework of critical coupling. Most importantly, we experimentally verify polaritonic CPA in a semiconductor-based intersubband-polariton photonic-crystal membrane resonator.This result opens new avenues in the exploration of polariton physics, making it possible to control the pumping efficiency of a system almost independently of its Rabi energy, i.e., of the energy exchange rate between the electromagnetic field and the material transition.

Mid-infrared intersubband polaritons in dispersive metal-insulator-metal resonators

“…Interestingly, this general concept also holds for the regime of strong coupling, as developed in Ref. 28 . To this scope, it is necessary to add an additional oscillator to model the ISB plasmon, and introduce the light-matter coupling constant 29 .…”

Interference control of perfect photon absorption in cavity quantum electrodynamics

“…Recently it has been shown that the light fields coupled to an optical cavity with an intra-cavity absorber can be completely absorbed and no light can escape through the cavity [3][4][5][6][7][8]. Such a cavity-absorber system acts as a coherent perfect absorber and may be useful for a variety of fundamental studies and practical applications [9][10][11][12][13][14][15][16][17][18][19].…”

Perfect photon absorption in the nonlinear regime of cavity quantum electrodynamics

“…Specifically, it requires that the imaginary (absorptive) part of the refractive index of the absorber is equal in absolute value to that of the gain medium at the lasing threshold and the incident light fields match the time-reversed lasing fields. Such perfect coherent absorber and the resulting interferometric control may have practical applications in optics communications and photonic devices such as transducers, modulators, and optical switches and transistors [12][13][14][15].…”

“…Previous studies of perfect photon absorption are in the linear absorption regime, in which either a linear absorber is considered (such as in a solid-state Fabry-Perot etalon [6][7][8][9][10][11][12]) or in CQED, only the linear excitation of the first-order polariton states [19][20][21][22][23][24][25] are considered [19] and the multiphoton excitation of the higher-order polariton states in CQED are excluded [26][27]. Naturally this raises a question on whether coherent perfect photon absorption can occur in an optical system with a nonlinear absorber.…”