The invention relates to a beam polarization rotator, which comprises: (a) a waveguide having an input facet, an output facet, and four side facets; (b) a core material of the waveguide having a first refractive index; (c) a coating material of the side facets having a refractive index lower than said refractive index of the core material; wherein the waveguide has a cuboid-twisted shape, such that a distal portion of an originally cuboid body is twisted at an angle α about a longitudinal-central axis of the waveguides body, while a proximal portion of the body remains fixed relative to said axis, resulting in said output facet be at an offset orientation angle α relative to the orientation of said input facet.

A coaxial lidar system includes one or more emitter channels and one or more sensor channels that share an optical module. A diffractive waveguide can be used to redirect received light from the shared optical module to the sensor channels.

Foldable and folded light guide articles are described. Foldable light guide articles include a backing, a light guide disposed upon the backing and a prism disposed upon the backing adjacent to the light guide such that when the backing is folded about an axis between the prism and the light guide, a side of the prism is positioned adjacent to and aligned with an end of the light guide. Folded light guide articles include a light guide, a first prism and a second prism. The first prism is disposed adjacent to and aligned with an end of the light guide. The second prism is disposed adjacent to and aligned with the first prism with a low-index material separating the first prism and the second prism.

Foldable and folded light guide articles are described. Foldable light guide articles include a backing, a light guide disposed upon the backing and a prism disposed upon the backing adjacent to the light guide such that when the backing is folded about an axis between the prism and the light guide, a side of the prism is positioned adjacent to and aligned with an end of the light guide. Folded light guide articles include a light guide, a first prism and a second prism. The first prism is disposed adjacent to and aligned with an end of the light guide. The second prism is disposed adjacent to and aligned with the first prism with a low-index material separating the first prism and the second prism.

An optical device includes a light source configured to provide illumination light and a waveguide. The waveguide has an input surface, an output surface distinct from and non-parallel to the input surface, and an output coupler. The waveguide is configured to receive, at the input surface, the illumination light provided by the light source and propagate the illumination light via total internal reflection. The waveguide is also configured to redirect, by the output coupler, the illumination light so that the illumination light is output from the output surface for illuminating a spatial light modulator.

Various example embodiments relate to active optical fibers and devices using active optical fibers. An active optical fiber may comprise a central part surrounded by an annular active core. The fiber may have a tapered longitudinal profile such that the fiber comprises a single-mode portion and a multimode portion. The annular core may have low birefringence, obtained for example by rotating (spinning) the fiber preform during manufacture of the fiber. Refractive index of the annular core may be higher than the refractive indices of the central part and cladding layer(s) surrounding the annular core. The active optical fiber enables selective generation or amplification of light modes with orbital angular momentum (OAM). Furthermore, the fiber has a large mode field diameter (MFD) and it is not sensitive to internal heating or environmental influences.

Single-photon detector apparatus comprising a large core optical fiber with a core diameter larger than 8 .Math.m, a small core optical fiber with a core diameter smaller or equal to 5 .Math.m, a taper between the large core optical fiber and the small core optical fiber, a superconducting nanowire having a surface area configured to receive all photons emitted from the small core optical fiber and cost effective and high yield method for manufacturing such.

Devices for radiative cooling and optical waveguiding are provided, wherein the devices comprise a fabric including one or more fibers extending for a length in a longitudinal direction and a plurality of void structures positioned within each of the one or more fibers and extended over the length of each of the one or more fibers. Each of the plurality of void structures is configured to scatter at least a portion of an electromagnetic radiation received thereon to thereby radiatively cool the object.

Devices for radiative cooling and optical waveguiding are provided, wherein the devices comprise a fabric including one or more fibers extending for a length in a longitudinal direction and a plurality of void structures positioned within each of the one or more fibers and extended over the length of each of the one or more fibers. Each of the plurality of void structures is configured to scatter at least a portion of an electromagnetic radiation received thereon to thereby radiatively cool the object.

An assembly for redirecting light emitted by an end-emitting optical fiber into an inner lumen of a body is provided. According to one implementation, the body includes one or more surfaces disposed on or in the body onto which the light is configured to impinge when the end emitting optical fiber is activated, the one or more surfaces being configured to alter the trajectory of the light so that the light is directed to impinge on a light reflector of a cap removably attached to the body, the light reflector of the cap being configured to redirect the light distally into the inner lumen of the body.