Described herein is a wavelength reference device comprising a housing defining an internal environment having a known temperature. A broadband optical source is disposed within the housing and configured to emit an optical signal along an optical path. The optical signal has optical power within a wavelength band of interest. An optical etalon is also disposed within the housing and positioned in the optical path to filter the optical signal to define a filtered optical signal that includes one or more reference spectral features having a known wavelength at the known temperature. The device also includes an optical output for outputting the filtered optical signal.

In some implementations, an optical assembly comprises an optical cavity; one or more detectors; and an optical component having an input face and an output face configured to receive an input beam to the input face and to produce one or more primary output beams, and a plurality of secondary output beams from the output face, the secondary output beams resulting from multiple internal reflections within the optical component. At least one of the input face is not perpendicular to the input beam or the output face is not perpendicular to the one or more primary output beams. Each primary output beam is transmitted through the optical cavity perpendicular to at least one surface of the optical cavity, and directed to a respective one of the one or more detectors. Each detector is arranged to exclude at least a portion of each secondary output beam.

Systems and methods provide technology for a tunable vehicle window system to adjust a view for a window. The technology includes a window assembly comprising a tunable optical metamaterial deployed on a surface of a window, the tunable optical metamaterial including a transparent electroactive substrate having disposed thereon an optically active particle array, the optically active particle array including resonators having elongated members arranged in two or more orientations. The technology includes a controller to receive a signal from a photosensor indicative of a condition of incoming light to the vehicle, determine a change in a view for the window assembly based on the received photosensor signal, and control a voltage applied to the substrate to selectively expand or contract the substrate within a plane substantially parallel to the window surface and in a manner to adjust the view for the window assembly according to the determined view change.

An apparatus including an optical resonator, and a method of using same. The optical limiter includes an optically absorbent material. The optical resonator supports a plurality of resonant transmission peaks at resonant frequencies defined by the cavity length. The optically absorbent material exhibits a saturable absorption response at a fundamental absorption peak located spectrally at a fundamental absorption peak frequency of the plurality of resonant transmission peaks. The optically absorbent material includes an absorptivity sufficient for strong cavity coupling, such that the fundamental absorption peak splits into a first upper vibration polariton transmission peak and a second lower polariton transmission peak separated by a Rabi splitting. The Rabi splitting is proportional to a square root of the absorptivity. The absorptivity varies with optical excitation of the optically absorbent material. The absorptivity is maximized at a photon-unsaturated ground state, and the absorptivity is minimized at an optically excited state.

A hyperspectral imager (HSI) includes a first thin film filter, the first thin film filter including a first quarter wave mirror, a second quarter wave mirror, and a low-refractive-index wedge between the first quarter wave mirror and the second quarter wave mirror. The low-refractive-index wedge has a height dimension such that a distance between the first quarter wave mirror and the second quarter wave mirror increases linearly along a length of the low-refractive-index wedge.

Methods and apparatus for providing spectrally beam-combined fiber-based transmitters and/or receivers for laser communications, LiDAR, and similar devices. A transmitter can include a launch array configured to spatially position each output beam of pulsed lasers, a transform optical component to correct deflection of the output beams of the pulsed lasers from the launch array, and a dispersive optical element to combine beams from the transform optical element and generate a spectrally combined beam. A receiver can include spectral comb filters to spectrally discriminate multi-wavelength detected signals from background illumination.

An optical filter includes an active filter region including at least one of a spectral filter and a polarizing filter; and a reference filter region configured to sense an amount of light passing through the active filter region, wherein the reference filter region includes a gray filter and at least one of a black filter and a transparent filter, wherein the gray filter has a transmittance that is higher than a transmittance of the black filter and lower than a transmittance of the transparent filter.

A Fabry-Perot interference filter includes: a substrate; a first laminated body including a first mirror portion; a second laminated body including a second mirror portion; an intermediate layer including a defining portion that defines the gap between the first laminated body and the second laminated body; a first electrode formed in a first layer constituting the first laminated body; and a second electrode formed in a second layer constituting the second laminated body. The intermediate layer further includes a covering portion that covers outer edges of a plurality of layers including the first layer among layers constituting the first laminated body; and an extending portion that extends outward from the covering portion. The second laminated body extends to cover a stepped surface formed between the defining portion and the extending portion by the covering portion and an outer end surface of the extending portion.

A direction-selective interferometric optical filter for spectrometric devices, at least includes an arrangement of two layered one-dimensional photonic structures. Each of the two structures contains a defect layer, and each photonic structure has a dispersion function in the energy momentum space (E, kx, ky), wherein kx and ky are momentum components of transmitted photons of the photonic structures for a defined energy (frequency/wavelength) E in the energy momentum space. Both photonic structures have opposite interfaces which are at a plane-parallel distance from one another. In this case, the dispersion functions of both photonic structures cross or intersect in the energy momentum space and produce a cut set of rays of waves on the surfaces of the dispersion functions at a particular energy, wherein a ray of waves contains waves selectively chosen through the filter at an angle, while other waves are reflected by the filter at other angles.

Disclosed is a metrology apparatus comprising an optical element configured to receive at or near a pupil plane of the metrology apparatus, at least first radiation comprising a first higher diffracted order and second radiation comprising a zeroth order resulting from illumination of a metrology target with radiation; and to direct said first radiation and second radiation together in a first direction. The metrology apparatus is further configured to form at least a first image of a first interference pattern, the first interference pattern resulting from interference of said first radiation and second radiation at an image plane.