A semiconductor photodetector comprising a closed loop configured to receive light from an external source adapted to trap light within said closed loop until absorption by the semiconductor.

The purpose of the present invention is to provide an optical member and the like which enable suppression of diffusion of stray light due to a pigment even when the optical member and the like are used adjacent to a light guiding part through which incident light is transmitted. The optical member is configured to be used adjacent to the light guiding part through which the incident light is transmitted and to attenuate the incident light. The optical member has a dispersed carbon particle part that is formed as a result of dispersion of carbon particles in a particular region in a silicone resin. The carbon particles are stray light diffusion suppressing particles for suppressing the intensity of light being incident onto the carbon particles and diffused.

When routing light on photonic integrated circuit (PIC) chips optical back-reflection and scattering can be highly detrimental to the desired application. Unused ports of optical devices, such as MMI, DC, Y-junction, PD, etc. are a cause for back-reflection and scattering, whereby the scattered light could get picked up by adjacent components, e.g. photodetectors. Management of stray light on the PIC is needed to prevent the undesired coupling between various components and to reduce noise. A dump taper may be used to guide and scatter stray light away from sensitive components or fully absorb the light while maintaining very low reflection from the taper. A doped dump taper may be used to passively absorb light reaching the unused port, thereby eliminating unwanted reflection and scattering. Alternatively, an undoped taper may be used to scatter light away from sensitive components while maintaining very low back-reflection.

In a multicore optical fiber sensor, an absorptive material integrated into the cladding, or into a waveguide core not used for sensing, may facilitate sensing. The absorptive material is absorptive to light in a wavelength band in which the fiber sensor is configured to operate. Coating such a fiber sensor with a material whose refractive index is smaller than that of the cladding may be done with reduced signal mixing.

Embodiments of the invention include a method of initiating an optical fiber. In some embodiments, a distal portion of the optical fiber is coated with an energy absorbing material. In some embodiments, the material includes a metal flakes or powder dispersed in a solution of organic solvents. After the material dries, laser energy is fired through the optical fiber. The laser energy can be absorbed in the material and ignites the organic solvents. This combustion melts the material of the optical fiber, and impregnates the optical fiber with the metal flakes or powder of the material. The resulting optical fiber is thus permanently modified so that the energy applied through the fiber is partially absorbed and converted to heat.

Disclosed herein are methods, structures, apparatus and devices for the termination of unused waveguide ports in planar photonic integrated circuits with doped waveguides such that free-carrier absorption therein may advantageously absorb any undesired optical power resulting in a significant reduction of stray light and resulting reflections.

An apparatus for coupling out radiation from an optical fiber, includes a housing, and a stop having a stop opening for delimiting an output coupling angle of radiation that is coupled out of an output end of the optical fiber to a maximum output coupling angle with respect to a central axis of the stop opening, wherein the stop is arranged in the housing. The stop has a stop body made from a transparent material, the stop body has a first total internal reflection face for reflecting radiation that is coupled out of the output end of the optical fiber with greater output coupling angles than the maximum output coupling angle, and the stop body has a second total internal reflection face for reflecting radiation that propagates opposite to the radiation coupled out of the output end and is reflected back by a workpiece.

A lighting device includes a light source, a light guide plate, an optical sheet, and a light blocking member. The light guide plate includes a section of a peripheral surface opposed to the light source defined as a light entering surface, a section of the peripheral surface opposite from the light entering surface defined as an opposite surface, and a light exiting plate surface through which light exits. The optical sheet is disposed over the light exiting plate surface. The light blocking member is in an outer edge area of at least one of the light guide plate and the optical sheet to block the light from the light guide plate through the light exiting plate surface. The light blocking member extends in a peripheral direction along the peripheral surface in which the light entering surface and the opposite surface are arranged.

An optical waveguide termination comprising a light-receiving inlet for receiving light to be terminated, a curved section extending from the inlet and having a continuously decreasing radius of curvature, and a light-terminating tip at an end of the curved section. The curved section may define a spiral waveguide, for example a logarithmic spiral, having a waveguide width that continuously decreases from the inlet to the tip.

When routing light on photonic integrated circuit (PIC) chips optical back-reflection and scattering can be highly detrimental to the desired application. Unused ports of optical devices, such as MMI, DC, Y-junction, PD, etc. are a cause for back-reflection and scattering, whereby the scattered light could get picked up by adjacent components, e.g. photodetectors. Management of stray light on the PIC is needed to prevent the undesired coupling between various components and to reduce noise. A dump taper may be used to guide and scatter stray light away from sensitive components or fully absorb the light while maintaining very low reflection from the taper. A doped dump taper may be used to passively absorb light reaching the unused port, thereby eliminating unwanted reflection and scattering. Alternatively, an undoped taper may be used to scatter light away from sensitive components while maintaining very low back-reflection.