Coherent Virtual Absorption Based on Complex Zero Excitation for Ideal Light Capturing

TL;DR

This paper introduces coherent virtual absorption, a method to access complex scattering zeros via waveform shaping, enabling energy storage and release in lossless structures with potential applications in light control and optical memory.

Contribution

It presents a novel concept of coherent virtual absorption that utilizes complex zeros for energy storage, overcoming limitations of traditional absorption methods.

Findings

Enabling energy storage and release in lossless structures.

Robustness against material dissipation.

Applicable to systems with multiple input ports.

Abstract

Absorption of light is directly associated with dissipative processes in a material. In suitably tailored resonators, a specific level of dissipation can support coherent perfect absorption, the time-reversed analogue of lasing, which enables total absorption and zero scattering in open cavities. On the contrary, the scattering zeros of lossless objects strictly occur at complex frequencies. While usually considered non-physical due to their divergent response in time, these zeros play a crucial role in the overall scattering dispersion. Here, we introduce the concept of coherent virtual absorption, accessing these modes by temporally shaping the incident waveform. We show that engaging these complex zeros enables storing and releasing the electromagnetic energy at will within a lossless structure for arbitrary amounts of time, under the control of the impinging field. The effect is robust with respect to inevitable material dissipation and can be realized in systems with any number of input ports. The observed effect may have important implications for flexible control of light propagation and storage, low-energy memory, and optical modulation.