Pico- and nanophotonics of reconfigurable metamaterials

Abstract

Picophotonics is the emerging science of light-matter interactions at the subnanometre scale. In nanomechanical metamaterials (NMs), picometric movements driven by thermal forces can be amplified by optical forces, opening up a novel way to explore their physics and applications. In this work I have: • Designed and constructed a unique apparatus for investigation of thermal fluctuations and directional asymmetry of optical properties in NMs. This experimental setup is part-fiberized for stability, operating at telecommunications C-band wavelengths. • For the first time, observed thermal fluctuations in the optical properties of metamaterials. High-frequency time-domain fluctuations of the optical properties of NMs are directly linked to picometre thermal motion of their components and can give information on fundamental mechanical frequencies and damping of mechanical modes. At room temperature the magnitude of metamaterial transmission and reflection fluctuations is of order 0.1% but may exceed 1% at optical resonances. • Demonstrated, for the first time, that the natural frequencies and thermal fluctuation amplitudes of NMs can be optically controlled at µW/µm² intensities. The few - MHz natural frequencies of beams shift up to 3.6% and few tens of pm displacement amplitudes of thermal fluctuations vary up to 4.3% with light intensity of 0.8µW/µm² , providing active control of frequency response and may serve as a basis for bolometric, mass and stress sensing. • For the first time, reported asymmetric transmission in a nanomechanical metamaterial driven by optical forces. I have experimentally demonstrated in NMs that resonant excitation of optical and mechanical sub-systems can lead to profound light-induced transmission asymmetry reaching 16% at µW power levels, making it suitable for a range of laser technology and fibre telecom applications. • Shown, for the first time, that a free-standing, homogenous dielectric thin film can exhibit an optical magnetic response, i.e. without metamaterial nanostructuring. Indeed, such a response is an essential feature of homogeneous dielectric films at Fabry–Perot resonances, which are formed by the interference of electromagnetic multipoles, including the magnetic dipole.

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Identifiers

ORCID for Jinxiang Li: orcid.org/0000-0003-2792-7773

ORCID for Kevin MacDonald: orcid.org/0000-0002-3877-2976

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