A photo detector includes a variable optical attenuator provided on a substrate, an optical 90-degree hybrid device provided on the substrate, and a plurality of photodiodes provided on the substrate. The plurality of photodiodes are optically coupled to the variable optical attenuator via the optical 90-degree hybrid device. The variable optical attenuator includes an optical waveguide disposed on the substrate, a heater configured to heat the optical waveguide, and an insulating layer at least partially disposed between the substrate and the optical waveguide.

An optical device includes a waveguide configured to guide light, a taper integrated with the waveguide on a substrate configured for optical coupling, and an attenuator to degrade unwanted optical signal from the taper. The attenuator extends along one side of the taper, and includes one of a conductive structure, a doped structure and a refractive structure.

A passive self-alignment fiber-to-fiber optical device is provided. The device includes a silicon base, a fiber alignment region, and an actuation region. When the device is configured as a fiber optical attenuator, displacement of a plunger in the actuation region alters the alignment of two optical fibers in the fiber alignment region, thereby varying the optical intensity between the two fibers. A series of beams in the actuation region successively reduces an initial displacement of a first beam to a smaller displacement of the plunger. When the device is configured as an optical switch, displacement of the plunger in the actuation region displaces the first optical fiber from a first position in alignment with the second optical fiber into a second position in alignment with a third optical fiber.

The present disclosure is directed to photonic wavelength division multiplexing (WDM) receivers with polarization diversity and/or low reflectance. In embodiments, a WDM receiver is provided with a splitter, a plurality of waveguides and a plurality of photodetectors in series. The waveguides having particular equal path lengths relationship from the splitter to respective ones of the photodetectors. In other embodiments, the WDM receiver is provided with a splitter, a looped waveguide, a plurality of photodetectors, and a plurality of variable optical attenuators (VOAs). The VOAs are configured to suppress reflection of signal beams back to the transmitter. In various embodiments, the WDM receiver is a receiver sub-assembly of a silicon photonic transceiver disposed in a silicon package. Other embodiments may be described and/or claimed.

The present disclosure relates to a polarity detector for detecting polarity of a patch cord, that is capable of sequentially inputting an optical signal into channels of a connector of the patch cord, receiving the optical signal being output, and thereby discerning the polarity of the patch cord quickly and precisely. Particularly, the present disclosure is characterized to spectrally output the optical signal from the light source as a plurality of unit optical signals, and to selectively block or pass the spectrally output plurality of unit optical signals, by heat, and thereby effectively inputting the optical signal into each channel of the connector.

An optical device includes a waveguide configured to guide light, a taper integrated with the waveguide on a substrate configured for optical coupling, and an attenuator to degrade unwanted optical signal from the taper. The attenuator extends along one side of the taper, and includes one of a conductive structure, a doped structure and a refractive structure.

A variable wavelength filter includes: an input optical fiber; a diffraction grating that disperses input light from the input optical fiber; a variable mirror that has a reflective surface, wherein an angle of the reflective surface is adjustable, the variable mirror reflects the input light dispersed by the diffraction grating, the input light reflected by the variable mirror passes through a normal optical path, the input light that passes through the normal optical path has a wavelength band defined based on the angle of the reflective surface, and the defined wavelength band has a center wavelength corresponding to the angle of the reflective surface; an output optical fiber that outputs a portion of the input light that has passed through the normal optical path; and an optical detector disposed on a propagation path of the input light from the input optical fiber to the output optical fiber.

An optical fiber laser device generates laser light by using an optical amplifying fiber as an amplification medium in a laser oscillator and includes: an optical outputting fiber configured to emit laser light to an outside; a return-light-attenuating portion configured to perform an attenuation process to return light propagating through at least the optical outputting fiber in a reverse direction of the laser light; a thermal conversion unit provided at the return-light-attenuating portion and configured to convert the return light into heat; a temperature-monitoring device configured to measure an increase in a temperature, of the return-light-attenuating portion, caused by the heat converted by the thermal conversion unit; and a control unit configured to decrease or stop an output of the laser light when the temperature measured by the temperature-monitoring device becomes a predetermined threshold temperature or higher.

A display system includes a first light source, a second light source, at least one movable mirror, and an attenuator. The first light source is configured to provide a first light in a first optical path. The second light source is configured to provide a second light in a second optical path. A portion of the second optical path overlaps the first optical path in an overlapping portion. The attenuator is positioned in at least the first optical path and configured to attenuate at least the first light. The movable mirror is movable to deflect the overlapping portion.

A depolarizer for a broadband optical source to split the source beam by power, not by polarization state, and route the components into respective light paths. A polarization rotator arranged in one of the light paths rotates the polarization state of that beam component to make it orthogonal to that of the other. The components are then recombined by a combiner and output. A variable optical attenuator is arranged in one of the light paths, which during operation is adjusted by a controller to maintain power equalization between the light paths and hence depolarization performance. The controller receives power measurements from the light paths and from after the combiner via respective sensors. With this feedforward design reminiscent of a Mach-Zehnder interferometer the light from a light source which generates highly polarized light can be depolarized in theory with zero insertion loss and in practice with losses of about 1 dB.