The present disclosure is directed to systems and methods for omniresonant broadband coherent perfect absorption of incoherent light over large bandwidths. The apparatus and methods that enable 100% effective optical absorption in a structure, irrespective of the material from which it is constructed, over a large, continuous bandwidth (omniresonance) in ultrathin devices. Specifically, we demonstrate achromatic optical absorption (omniresonance) in a planar Fabry-Pérot micro-cavity via angularly multiplexed phase-matching. By assigning each wavelength to an appropriate angle of incidence, the micro-cavity is rendered absorbing with continuous spectral range. For example, the linewidth of a single-order 0.7 nm wide resonance is de-slanted in spectral-angular space to become a 70 nm wide achromatic resonance spanning multiple cavity free spectral ranges. The embodied invention can have important applications in, e.g., harvesting solar energy, white-light micro-lasers, and other broadband resonantly enhanced optical effects.

A tunable liquid crystal (LC) device includes an LC layer between a pair of reflectors forming an optical cavity. The reflectors include conductive layers for applying an electrical signal to the LC layer. One of the conductive layers may include an array of conductive pixels for spatially selective control of the effective refractive index of the LC layer. The phase delay introduced by the LC layer may be greatly increased or magnified by placing the LC layer into the optical cavity. This enables a substantial reduction of the LC layer thickness, which in its turn enables very tight pitches of the LC pixels, with a reduced inter-pixel crosstalk caused by fringing electric fields, as well as faster switching times. A tight-pitch, fast LC device may be used as a configurable hologram or a spatial light modulator.

A light filter and a spectrometer including the light filter are disclosed. The light filter includes a plurality of filter units having different resonance wavelengths, wherein each of the plurality of filter units includes a cavity layer configured to output light of constructive interference, a Bragg reflection layer provided on a first surface of the cavity layer, and a pattern reflection layer provided on a second surface of the cavity layer opposite to the first surface and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer including a plurality of reflection structures that are periodically arranged.

The present application relates to a filter module, a color filter, an image sensor and an imaging device. The filter module includes: a plurality of color filters and a control component. Each of the color filters includes: a first substrate; a metasurface structure located on the first substrate and including a plurality of microstructures periodically arranged; a dielectric layer located on a side of the metasurface structure away from the first substrate and covering the metasurface structure, wherein a refractive index of the dielectric layer is different from a refractive index of the metasurface structure; a second substrate located on a side of the dielectric layer away from the first substrate. The control component is configured to adjust the refractive index of the dielectric layer so as to adjust wavelengths of visible light passing through the color filter.

The invention relates to a switchable absorber element and a photovoltaic cell based thereon. A switchable absorber element according to the invention has an absorber layer. The absorber element furthermore has at least one front side reflection layer and at least one rear side reflection layer, wherein the absorber layer is arranged between front side reflection layer and rear side reflection layer, wherein the optical path length between front side reflection layer and rear side reflection layer is less than 400 nm at least for light impinging perpendicularly onto the cell. The absorber element according to the invention is characterized in that at least one of the reflection layers has a switchable reflectivity.

An optical transmitter and a method of producing a low-photon-density modulated optical signal are disclosed. The optical transmitter and method include an optical source configured to emit a continuous optical carrier waveform, a dilation module configured to apply a spreading code to a data payload to spread each of the plurality of symbols in time to expand the symbol duration by a dilation factor and produce a corresponding plurality of time-dilated symbols, the plurality of time-dilated symbols having a lower photon density than the plurality of symbols; a mapping module configured to map the plurality of time-dilated symbols to a modulation scheme; and a modulator configured to modulate the optical carrier waveform with the plurality of time-dilated symbols according to the modulation scheme to produce the low-photon-density modulated optical signal encoded with the plurality of time-dilated symbols corresponding to the data payload.

An optical receiver includes a photonic integrator configured to accumulate optical signal energy corresponding to the input optical signal during an integration period, and to produce an output optical signal at an end of the integration period, the output optical signal having a higher intensity than the input optical signal, a shutter operable between a closed position and an open position, the shutter configured to prevent the output optical signal from exiting the photonic integrator when in the closed position and to allow the output optical signal to exit the photonic integrator when in the open position, a synchronizer coupled to the shutter and configured to control the shutter between the open position and the closed position; and a photodetector configured to receive the output optical signal when the shutter is in the open position and to produce an electrical signal corresponding to the output optical signal.

A light filter and a spectrometer including the light filter are disclosed. The light filter includes a plurality of filter units having different resonance wavelengths, wherein each of the plurality of filter units includes a cavity layer configured to output light of constructive interference, a Bragg reflection layer provided on a first surface of the cavity layer, and a pattern reflection layer provided on a second surface of the cavity layer opposite to the first surface and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer including a plurality of reflection structures that are periodically arranged.

A camera includes one or more spectral illuminators, a tunable optical filter optically intermediate the one or more spectral illuminators and a scene, and a sensor array. The one or more spectral illuminators are configured to emit active spectral light. The tunable optical filter is dynamically adjustable to change a selected sub-band of the active spectral light that illuminates the scene. The sensor array includes a plurality of sensors each configured to measure spectral light reflected from the scene in the selected sub-band.

In accordance with various embodiments of the disclosed subject matter, a system, device and method for an electrically tunable wavelength selection filter comprising a wavelength selection filter portion having a plurality of alternating thin films of two dielectric materials with a thin film capacitor displacing one pair of alternating thin films, and an order sorting filter portion electrically isolated from but proximate the wavelength selection filter and having a plurality of alternating thin films of two dielectric materials where one of the dielectric materials exhibits a voltage-dependent refractive index. Independently controlling the capacitor charging voltage and the voltage across the order sorting filter enables selective transmission of narrow spectral lines across a desired frequency region.