Chip technology for fabricating ultra-low-noise, high-stability optical devices for use in an optical atomic clock system. The proposed chip technology uses diamond material to form stabilized lasers, frequency references, and passive laser cavity structures. By utilizing the exceptional thermal conductivity of diamond and other optical and dielectric properties, a specific temperature range of operation is proposed that allows significant reduction of the total energy required to generate and maintain an ultra-stable laser. In each configuration, the diamond-based chip is cooled by a cryogenic cooler containing liquid nitrogen.

An apparatus comprises: a gain medium configured to be pumped by a pump source; a photonic integrated circuit (PIC) positioned in a laser cavity that includes the gain medium, the PIC comprising a substrate comprising silicon, a plurality of photonic structures, and one or more ports coupling an optical wave into the PIC, and coupling an optical wave out of the PIC; an optical isolator configured to limit propagation of an optical wave in a single direction through the optical isolator; and an output coupler configured to provide an output that comprises a fraction of the power of an optical wave that is incident upon the output coupler and to redirect remaining power of the optical wave around a closed path of the laser cavity, where the fraction is greater than 0.5.

An observation apparatus (100) includes an observing optical system (101) capable of obtaining an image of a measurement target present in a gap included in a device (1). One end of the gap included in the device (1) is wider than the other end thereof, and upon light beam irradiation to the device (1), an interference fringe appears in the gap. The observing optical system (101) irradiates the gap included in the device (1) with a plurality of light beams having different wavelengths to cause a plurality of interference fringes to appear in the gap. Then the observing optical system (101) obtains an image of the plurality of interference fringes.

An optical receiver that can tune a selected wavelength using a wavelength tunable filter transmitting a plurality of wavelengths. The optical receiver is a wavelength tunable optical receiver that includes: a wavelength tunable filter (100) transmitting laser light from an optical fiber; and a photodiode (300) receiving laser light passing through the wavelength tunable filter (100), in which the wavelength tunable filter 100 is a Fabry-Perot type etalon filter transmitting a plurality of wavelengths. When a channel with a specific wavelength is moved to a channel with another wavelength, an optical channel is selected based on a peak different from a transmissive peak of an FP etalon filter selecting the previous channel so that temperature of the wavelength tunable filter can be changed. A light-receiving photodiode chip is disposed on a thermoelectric element and a wavelength tunable filter transmits different wavelengths in accordance with temperature of the thermoelectric element.

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 transmissive optical device comprising: a layer (10) of light absorber material in the solid state, preferably made of a phase-change material with switchable refractive index such as GeSbTe; a partially-reflective layer (12), and a spacer layer (14) between the layer (10) of light absorber material and the partially-reflective layer (12). The spacer layer (14) and an optional coverlayer (16) may be transparent conductive ITO layers which may serve to electrically switch the phase of the phase-change material layer (10), thereby switching the transmission/reflection properties of the transmissive optical device.

A multi-spectral imaging system utilizing tunable optics is disclosed. Various disclosed systems include a tunable optical filter coupled to a broadband imaging system. The tunable optical filter allows discrete infrared wavelengths to pass to the broadband imaging system so that monochromatic infrared images of a scene may be captured. An image processing system may process selected monochromatic infrared images by using a ratio technique to generate an emissivity-independent thermal image of the scene. The tunable optical filter may also be used to adjust a quality factor and control an amount of radiated energy that is passed to an image sensor of the broadband imaging system thereby acting as an aperture to account for both low and high radiance portions of the scene.

A Fourier-transform interferometer includes a phase change plate including a reflective layer configured to reflect a first light that is incident, and a meta surface configured to locally and differently change a phase of the first light that is reflected. The Fourier-transform interferometer further includes a photodetector configured to detect a second light, and a transflective mirror and a mirror configured to transmit a first part of a third light that is incident, to the phase change plate, transmit a remaining part of the third light, to the photodetector, and transmit the first light of which the phase is locally and differently changed, to the photodetector. The photodetector is further configured to detect an interference pattern between the remaining part of the third light and the first light of which the phase is locally and differently changed.

A plasmonic switching device and method of providing a plasmonic switching device. An example device includes a resonant cavity and an electromagnetic radiation feed arranged to couple electromagnetic radiation into the resonant cavity and at least one plasmonic mode. The resonant cavity is arranged to be switchable between: a first state in which the resonant cavity has an operational characteristic selected to allow resonance of the electromagnetic radiation at a frequency of the at least one plasmonic mode; and a second state in which the operational characteristic of the resonant cavity is adjusted to inhibit resonance of the electromagnetic radiation at a frequency of the at least one plasmonic mode.

A device according to one example of principles described herein may include a backplane, electrochemical actuator, and an optical resonator, wherein the electrochemical actuator is located between the backplane and optical resonator. Applied energy may be used to modify the volume of the electrochemical actuator material modifying the resonant/interferometric absorption, transmission, and reflection at visible and/or infrared frequencies.