A photodetector includes a substrate, a material layer, a first electrode made of a metal, a core, a second electrode and a light absorption layer made of graphene. The first electrode, the core, and the material layer constitute a hybrid plasmonic waveguide, and the light absorption layer is disposed thereon. Light guided in the hybrid plasmonic waveguide is absorbed by the light absorption layer, photoelectrically converted by the PTE effect, and extracted as an electric signal from the first electrode and the second electrode.

The objective of the present invention is to provide an optical modulator adapted for use with various modulating units and various modulation regions, and with which variability in optical losses is limited as far as possible. An optical modulator in which an optical waveguide and a control electrode for controlling an optical wave propagating through the optical waveguide are provided in a substrate, characterized in that: the optical waveguide is provided with a first branching portion which causes one input light beam to branch into two light beams; each of a first and a second modulating portion connected to two branched waveguides which branch at the first branching portion is provided with a structure in which one or more Mach-Zehnder type optical waveguides are combined; the control electrode comprises signal electrodes which apply modulated signals to the first and second modulating portions; input portions of all the signal electrodes are disposed on either the left or the right of the substrate relative to the direction in which the optical wave propagates; and in relation to output portions of the signal electrodes, the output portions of the signal electrodes led out from each modulating portion are disposed on the side on which the first or second modulating portions are disposed, relative to the direction in which the optical wave propagates.

A shape estimation apparatus includes: a light guide to guide light emitted from a light source; a detection target, provided in the light guide, to change a light quantity of guided light according to the curved state of the light guide; a light detector to detect a light quantity that has been changed; and a curvature arithmetic operator to calculate information related to a curve of the light guide based on the detected light quantity. The light detector includes a light receiving element. The operator calculates information related to the curve of the light guide in which an error of the light detector caused by noise containing dark current of the light detector is corrected based on an output of a part of the light receiving element that the light from the light source does not enter.

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.

An optical waveguide termination device includes a waveguide and metal vias surrounding an end portion of the waveguide. The end portion of the waveguide has a transverse cross-sectional area that decreases towards its distal end. The metal vias are orthogonal to a same plane, with the same plane being orthogonal to the transverse cross-section. The metal vias absorb light originating from the end portion when a light signal propagates through the waveguide, and the metal vias and the end portion provide that an effective index of an optical mode to be propagated through the waveguide progressively varies in the end portion. Additional metal vias may be present along the waveguide upstream of the end portion, with the additional metal vias bordering the waveguide upstream of the end portion providing that the effective index of an optical mode to be propagated through the waveguide varies progressively toward the end portion.

An optical waveguide termination includes a light-receiving inlet for receiving light to be terminated, a rib waveguide extending from the inlet, a doped, light-absorbing slab supporting the rib waveguide for absorbing light from the rib waveguide, and a tip at an end of the rib waveguide. The optical waveguide termination exhibits low back-reflection.

A photodetector includes a substrate, a material layer, a first electrode made of a metal, a core, a second electrode and a light absorption layer made of graphene. The first electrode, the core, and the material layer constitute a hybrid plasmonic waveguide, and the light absorption layer is disposed thereon. Light guided in the hybrid plasmonic waveguide is absorbed by the light absorption layer, photoelectrically converted by the PTE effect, and extracted as an electric signal from the first electrode and the second electrode.

Embodiments may relate to a silicon photonic chip, and particularly a back absorber within the silicon photonic chip. The back absorber may include a substrate material with a slab portion that includes a doped portion of the substrate material. The back absorber may be positioned at the backside of a laser that is configured to project light along a waveguide of the silicon photonic chip. Other embodiments may be described or claimed.

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.

A display device is provided. The display device includes a display panel and a backlight module, the backlight module is corresponding disposed to the display panel. The backlight module emits a backlight having a backlight spectrum. The backlight spectrum includes a first waveband and a second waveband. The first waveband is within a range of 380 nm to 480 nm, and has a first integrated light intensity I(B). The second waveband is within a range of 481 nm to 600 nm, and has a sub-waveband within a range of 550 nm to 600 nm. The sub-waveband has a integrated light intensity I(G), and a ratio of the integrated light intensity to the first integrated light intensity (I(G)/I(B)) is within a range of 5% to 35%.