We demonstrate a non-contact optical magnetic field sensor that is based on actuation of a metamaterial-microcavity by the magnetic Lorentz force. Magnetic field is transduced to a change of the sensor’s reflectivity. The microscale proof-of-concept metamaterial magnetometer can be read from a distance and offers 60  μm spatial, about 10 μs temporal, and sub-microtesla magnetic field resolution.

Bolometers are detectors of electromagnetic radiation that usually convert the radiation-induced change in temperature of the detector into electric signals. Temperature-dependent electrical resistance in semiconductors and superconductors, the thermoelectric effect in thermocouples, and the pyroelectric effect of transient electric polarization of certain materials when they are heated or cooled are among the underlying physical phenomena used in bolometers. Here, we report that the dependence of the fundamental frequency of a nanowire string detected via scattering of light on the string can be used in a bolometer. Arrays of such nanowires can serve as detectors with high spatial and temporal resolution. We demonstrate a bolometer with 400 nm spatial resolution, 2–3 µs thermal response time, and optical power detection noise floor at 3–5 nW/Hz1/2 at room temperature.

The combination of optical and mechanical resonances offers strong hybrid nonlinearities, bistability, and the ability to efficiently control the optical response of nanomechanical photonic metamaterials with electric and magnetic field. While optical resonances can be characterized in routine transmission and reflection experiments, mapping the high‐frequency mechanical resonances of complex metamaterial structures is challenging. Here, it is reported that high‐frequency time‐domain fluctuations in the optical transmission and reflection spectra of nanomechanical photonic metamaterials are directly linked to thermal motion of their components and can give information on the fundamental frequencies and damping of the mechanical modes. This is demonstrated by analyzing time‐resolved fluctuations in the transmission and reflection of dielectric and plasmonic nanomembrane metamaterials at room temperature and low ambient gas pressure. These measurements reveal complex mechanical responses, understanding of which is essential for optimization of such functional photonic materials. At room temperature the magnitude of the observed metamaterial transmission and reflection fluctuations is of order 0.1% but may exceed 1% at optical resonances.

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Metastable optically controlled devices (optical flip‐flops) are needed in data storage, signal processing, and displays. Although nonvolatile memory relying on phase transitions in chalcogenide glasses has been widely used for optical data storage, beyond that, weak optical nonlinearities have hindered the development of low‐power bistable devices. This work reports a new type of volatile optical bistability in a hybrid nano‐optomechanical device, comprising a pair of anchored nanowires decorated with plasmonic metamolecules. The nonlinearity and bistability reside in the mechanical properties of the acoustically driven nanowires and are transduced to the optical response by reconfiguring the plasmonic metamolecules. The device can be switched between bistable optical states with microwatts of optical power and its volatile memory can be erased by removing the acoustic signal. The demonstration of hybrid nano‐optomechanical bistability opens new opportunities to develop low‐power optical bistable devices.