327 research outputs found
Coherent Virtual Absorption Based on Complex Zero Excitation for Ideal Light Capturing
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.Comment: To be published in Optic
Nonlinear metal-dielectric nanoantennas for light switching and routing
We introduce a novel hybrid metal-dielectric nanoantenna composed of
dielectric (crystalline silicon) and metal (silver) nanoparticles. A
high-permittivity dielectric nanoparticle allows to achieve effective light
harvesting, and nonlinearity of a metal nanoparticle controls the radiation
direction. We show that the radiation pattern of such a nanoantenna can be
switched between the forward and backward directions by varying only the light
intensity around the level of 11 MW/cm, with the characteristic switching
time of 260 fs.Comment: 9 pages, 5 figures, submitted to New J. Phy
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