A passive dual polarization unit and coherent transceiver and/or receiver including one or more passive dual polarization units are provided. An example passive dual polarization unit includes a polarization splitter configured to split an input signal into a TE mode and TM mode signals; TE/TM splitters each designed to split the TE/TM mode signals into first TE/TM signals and second TE/TM signals; a first TE signal polarization rotation component for receiving the first TE signal and providing a third TM signal having the same magnitude and time dependence as the first TE signal; a first TM signal polarization rotation component for receiving the first TM signal and providing a third TE signal having the same magnitude and time dependence as the first TM signal; and TE/TM couplers that couple the second TE/TM signals and the third TE/TM signals to generate output TE/TM signals.

Disclosed are optical communications systems and optical receivers including one or more optical cavity resonators. In particular, disclosed are methods and apparatus that allow for beam pointing to be maintained while permitting the receiver to tune the optical resonator to suit the wavelength, data rate and modulation format of the incoming optical signal, without requiring a coherent receiver or adaptive optics in addition to optical resonators.

A system and method for ultrashort signal detection adds an optical weighting element upstream of a detector within a direct detection receiver. The optical weighting element is configured to generate an optical pulse that closely matches at least one ultrashort pulse within the input signal so that portions of the input signal that are nonoverlapping with the at least one ultrashort pulse are rejected.

An optical transmission/reception unit includes a carrier rotatable around an axis of rotation, an optical receiver arranged at the carrier on the axis of rotation so as to receive an optical reception signal from a first direction, an optical transmitter arranged at the carrier adjacent to the optical receiver so as to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the axis of rotation above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic, wherein the reception optic is configured to guide the optical reception signal striking the transmission/reception optic towards the optical receiver on the axis of rotation.

A first portion of incoming light and a second portion of incoming light travel in opposite directions within a first optical waveguide. A ring resonator in-couples the first portion of incoming light and the second portion of incoming light from the first optical waveguide, such that the first portion of incoming light and the second portion of incoming light travel in opposite directions within the ring resonator. A second optical waveguide is disposed to in-couple the first portion of incoming light and the second portion of incoming light couple from the ring resonator, such that the first portion of incoming light and the second portion of incoming light travel in opposite directions within the second optical waveguide away from the ring resonator. One or more photodetector(s) are optically connected to receive the first portion of incoming light and the second portion of incoming light from the second optical waveguide.

A new and improved tunable optical receiver based on thermal optics and controllers for technologies that require fast wavelength channel tuning. The device entails a thermal control system in which a wavelength tunable filter, a sensor and at least two thermal actuators enables fast tuning, which are controlled by advanced algorithms. The key compositions of both parts are outlined and their main requirements are discussed

An optic signal receiver is provided that comprises an optic signal detection unit an estimation unit, and a feedback control unit to provide a detector control signal. The optic signal detection unit comprises an adaptive optic module, a mode splitting module and a signal detection module, wherein the adaptive optic module is to modify a received optic input signal under control of the detector control signal into a multi-mode optic output signal, the mode splitting module is configured to branch the multi-mode optic output signal off into multiple reduced mode optic signals and the signal detection module is configured to issue a detection signal, the signal detection module comprising a plurality of signal detection sections that are each configured to measure an intensity of a respective one of the reduced mode optic signals and to provide a respective indicator indicative of the measured intensity as a component of the detection signal. The feedback control unit is configured to minimize a difference between the detection signal and a detection reference signal with the detector control signal. The estimation unit is configured to issue a further input signal to the feedback control unit based on a model of the optic signal detection unit.

An apparatus includes a direct-detection optical data receiver to receive a data-modulated optical carrier. The direct-detection optical data receiver includes an optical power splitter, an array of at least three optical intensity detectors, and a digital signal processor. The digital signal processor is connected to receive digital values of intensity measurements of each of the optical intensity detectors of the array and to recover data of the received data-modulated optical signal from the digital values of the intensity measurements. The first optical intensity detector is connected to receive light from the optical power splitter via a dispersive optical path and the remaining of the optical intensity detectors of the array are connected to receive light from the optical power splitter via a multiple input and multiple output passive optical processing unit. The passive optical processing unit is configured to optically mix light received on different optical inputs thereof.

A semiconductor device includes a first insulating film, a first optical waveguide and a second optical waveguide. The first insulating film has a first surface and a second surface opposite to the first surface. The first optical waveguide is formed on the first surface of the first insulating film. The second optical waveguide is formed on the second surface of the first insulating film. The second optical waveguide, in plan view, overlaps with an end portion of the first optical waveguide without overlapping with another end portion of the first optical waveguide.

A light-receiving device includes: a light guide plate that is a transparent member having, as main surfaces, a first surface and a second surface facing each other and has an emission end formed on at least one end portion of the light guide plate; a wave plate that is disposed on the first surface of the light guide plate and converts an optical signal of circularly polarized light into linearly polarized light; a hologram layer that is disposed on the second surface of the light guide plate and guides a traveling direction of the optical signal converted into the linearly polarized light toward the emission end of the light guide plate; and a light receiver that receives the optical signal emitted from the emission end of the light guide plate and converts the received optical signal into an electrical signal.