An apparatus comprising a switchable optical filter comprising a layer of switchable material, the switchable material comprising a photochromic/thermochromic, a photochromic/photochromic, or a photochromic/electrochromic compound; a first light source providing light of a wavelength that causes the switchable material to transition from a faded state to a dark state, or a dark state to a faded state; and a switch for controlling activation of the first light source

An irradiation device for an additively manufacturing apparatus may include a working beam generation device configured to provide a working beam, a modulation beam generation device configured to provide a modulation beam, and a solid-state optical modulator that includes a crystalline material that exhibits a change in refractive index in response to photoexcitation of free electrons within the crystalline material. The irradiation device may include a power source coupled to the solid-state optical modulator and configured to introduce free electrons into the crystalline material. The modulation beam may cause photoexcitation of the free electrons within the crystalline material. The photoexcitation of the free electrons within the crystalline material may cause the crystalline material to exhibit a change in refractive index. The working beam, when incident upon the crystalline material, may exhibit a change in one or more parameters, such as a phase shift, attributable at least in part to the change in refractive index exhibited by the crystalline material.

A first pixel with a first pixel sidewall is disclosed. A second pixel with a second pixel sidewall facing the first pixel sidewall is also disclosed. A first dynamic optical isolation material between the first pixel sidewall and the second pixel sidewall and configured to change an optical state based on a state trigger such that a light behavior at the first pixel sidewall for a light emitted by one of the first pixel and the second pixel is determined by the optical state, is also disclosed.

Disclosed in the present invention are a chalcogenide phase change material based all-optical switch and a manufacturing method therefor, relating to the field of optical communications. The all-optical switch comprises: stacked in sequence, a cover layer film, a chalcogenide phase change material film, an isolation layer film, a silicon photonic crystal, and a substrate. The silicon photonic crystal comprises a nano-porous structure such that the silicon photonic crystal has a Fano resonance effect. When the all-optical switch is used, the state of the chalcogenide phase change material film is controlled by means of laser, and the resonance state of the silicon photonic crystal is modulated to implement modulation of signal light transmissivity; the modulation range is within a communication band from 1500 nm to 1600 nm, thereby implementing an optical switch. The all-optical switch of the present invention has the characteristics of high contrast ratio, high rate and low loss.

A method is disclosed for controlling a laser device for a laser-induced refractive index change (URIC) of a polymer structure. The laser device is controlled by a control device such that it emits pulsed laser pulses in a shot sequence in a preset pattern into the polymer structure. The laser pulses are emitted with preset irradiation parameters for refractive index change of the polymer structure, wherein for adjusting an order of magnitude of the refractive index change, a spatial pulse distance of the laser pulses in the polymer structure is adapted and the further irradiation parameters are kept within respective preset irradiation parameter ranges.

Exemplary arrangements relate to methods for recording and reproducing holograms. A method of recording a hologram in a thresholded opto-magnetic medium (7) includes producing a collimated recording beam (1) with a pulsed laser. The intensity of the recording beam is selectively modulated by passage through a modulator (2). The recording beam is spatially shaped by passage through a shaping element (15). The shaped modulated recording beam is made convergent by passage through an aspheric lens (4). The convergent beam is deflected bidirectionally with a MEMS mirror (6) that is in operative connection with the modulator, such that multiple disposed locations on a surface of the medium are exposed to a constriction of the convergent shaped recording beam, causing a change in the medium in the locations. Reconstructing the hologram is carried out by illuminating the medium with a collimated laser beam and focusing with a lens, light from the illuminated medium onto a detection matrix. Additional methods of recording and reproducing holograms utilize alternative steps.

A device and methods for displaying representations of objects, solids, and surfaces volumetrically in a medium containing one or more photochromic compounds comprising at least one UVA light source arranged to project a beam of UVA radiation and irradiate at least one portion of a display volume incorporating at least one display medium which includes at least one photochromic compound. The irradiance of the irradiated portion of the display medium being sufficient for clear-to-colored transitions of voxels of the display medium from a transparent state to a colored state. After a time period after the irradiation, the irradiated voxels activated in the colored state transition by a colored-to-clear transition into the transparent state.

A terahertz modulator includes a substrate and an organic semiconductor layer. A material of the organic semiconductor layer is graphitic carbon nitride, and the organic semiconductor layer is coated on a surface of the substrate. The terahertz modulator has a high on-off contrast and is able to reach a high modulation speed. A terahertz spatial light modulator includes a terahertz modulator and an automatic pumped light spatial modulator. The automatic pumped light spatial modulator is optically connected with the terahertz modulator. The terahertz spatial light modulator generates a patterned terahertz light, and the terahertz spatial light modulator has a high on-off contrast and is able to reach a high modulation speed.

Disclosed is a frequency-dependent microwave filter (1). The filter (1) comprises an enclosure (11) comprising a filter medium including at least one constituent of: atoms, molecules, ions, and point defects in an optically pumpable solid. The at least one constituent is excitable to an initial energy state. The filter (1) further comprises a field generator (12) configured to generate an inhomogeneous electric and/or magnetic field (12A) within the enclosure (11). The filter (1) further comprises means (13) for feedthrough of a microwave signal through the enclosure (11) and an optical pump (14) configured to periodically excite the at least one constituent of the filter medium to the initial energy state in alternation with the feedthrough of the microwave signal through the enclosure (11). Thereby, intensity-dependent filtering is achieved.

Various embodiments may provide a device for controlling an electromagnetic wave according to various embodiments. The device may include a medium. The device may further include an array of elements in contact with the medium and may be configured to receive the electromagnetic wave. Each element of the array of elements may include a phase change material configured to switch from, at least, a first state to a second state in response to an external input, thereby changing an optical property of the respective element to control the electromagnetic wave.