A terahertz polarization beam splitter based on a two-core negative curvature fiber is provided, which relates to the technical field of optical fiber communication. The polarization beam splitter includes: a base circular tube and core separation structures. Multiple large cladding tubes are internally tangent and connected to an inner wall of the base circular tube and arranged at equal intervals along a circumference of the inner wall of the base circular tube, and the multiple large cladding tubes are symmetrically distributed on the inner wall of the base circular tube. Embedded circular tubes are internally tangent and connected to inner walls of the multiple large cladding tubes respectively. The core separation structures are two in number.

An article of footwear is configured to be worn so as to at least partially cover a wearer's foot. The footwear includes at least one optical fiber on an internal surface of the footwear. The at least one optical fiber is configured to project radiation having a therapeutic wavelength through the at least one optical fiber and toward at least one of the wearer's foot, ankle or leg when the footwear is being worn so as to at least partially cover the wearer's foot.

Disclosed is a fraud detection method to authenticate that an object is formed of human skin. The method includes an object being placed on a home location on the surface of a propagation medium of a sensor, lighting the home location of the surface by a light source emitting light rays illuminating the home location forming with said surface a plurality of incidence angles encompassing a critical angle defined by the refraction index of the propagation medium and by a refraction index expected for authentic human skin, receipt by an imager of light rays from the surface, and acquisition of an image, and determining whether the object matches an authentic human finger based on the refraction index of said object, as a function of the spatial light distribution on the acquired image.

Disclosed herein are embodiments of an ultraviolet (UV) illumination system. The UV illumination system includes at least one UV light emitting diode (LED) and a light-diffusing optical fiber bundle. The light-diffusing optical fiber bundle includes a bundle jacket and a plurality of optical fibers disposed within the bundle jacket. Each optical fiber is made up of a glass core having a glass composition with less than 90 mol % silica and a cladding surrounding the glass core. At least one of the glass core or the cladding includes scattering centers. Further, the light-diffusing optical fiber bundle is optically coupled to the UV LED. Also disclosed herein are a UV light-diffusing fiber and a method of sterilizing an object using a UV illumination system contain a UV light-diffusing fiber.

In an example method of forming a waveguide film, a photocurable material is dispensed into a space between a first mold portion and a second mold portion opposite the first mold portion. Further, a relative separation between a surface of the first mold portion with respect to a surface of the second mold portion opposing the surface of the first mold portion is adjusted. The photocurable material in the space is irradiated with radiation suitable for photocuring the photocurable material to form a cured waveguide film. Concurrent to irradiating the photocurable material, the relative separation between the surface of the first mold portion and the surface of the second mold portion is varied and/or an intensity of the radiation irradiating the photocurable material is varied.

An integrated microwave photonics (IMWP) apparatus is provided using sapphire as a platform. The IMWP apparatus includes: a sapphire substrate having a step-terrace surface; and a III-V stack layer epitaxially grown on the sapphire substrate. The III-V stack layer includes: a first III-V layer disposed on the sapphire substrate; a low temperature (LT) III-V buffer layer disposed on the first III-V layer; multiple second III-V layers disposed and stacked on the LT III-V buffer layer; a third III-V layer disposed on the second III-V layers; a III-V quantum well layer disposed on the third III-V layers; and a fourth III-V layer disposed on the III-V quantum well layer. The second III-V layers are respectively annealed. A growth temperature of the LT III-V layer and a growth temperature of the III-V quantum well layer are lower than a growth temperature of each of the first, second, third and fourth III-V layers.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

An electronic device and a method for controlling an electronic device are provided. The electronic device includes a first side and a second side facing away from each other, where a frame is between the first side and the second side; the first side is provided with a display module that is at least partially light-permeable, and a gap is between the display module and the frame; a first light emitting device, a second light emitting device, and a light receiving device are inside the electronic device, the first light emitting device and the light receiving device are below the display module and corresponding to a light-permeable display region of display module, the first light emitting device emits a light signal to the outside through the light-permeable display region, and the second light emitting device emits a light signal to the outside through the gap.

A light guide comprising a polymeric layer at least 25 percent transmissive over at least a 30 nm bandwidth in a wavelength range from 180 to 280 nm over a distance of at least 100 micrometers and visible light transparent reflecting layers (UV-C mirror) that are at least 50 percent reflective over at least 30 nm bandwidth in a wavelength range from 180 to 280 nm over an incident light angle of 0 to 90 degrees and that are at least 25 percent transmissive of visible light over at least 30 nm bandwidth in a wavelength range of 400 to 800 nm over an incident light angle of 0 to 90 degrees. The light guide is useful, for example, for antimicrobial surfaces.