Proposed is a receiving UE for receiving a signal in optical wireless communication, according to the present disclosure. The receiving UE may include: a transceiver for receiving an optical signal of an orbital angular momentum (OAM) mode from a transmitting terminal; a demodulator composed of at least one phase shifter; a photoelectricity converter composed of at least one photodiode; and a processor connected to the transceiver, the demodulator, and the photoelectricity converter. In addition, the at least one phase shifter may convert an optical signal of the OAM mode into an optical signal of a Gaussian mode, and the at least one photodiode may convert an optical signal of the Gaussian mode into an electrical signal.

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, 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, and wherein the transmission optic is configured to displace onto the axis of rotation the optical transmission signal emitted by the optical transmitter.

An optical reception device including: a wavelength selection unit configured to split an optical signal amplified by an optical amplifier into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer, and control a passage state of a passage target optical switch through which the optical signal is to be passed, out of a plurality of optical switches provided on the respective paths, to select an optical signal of a path where the optical signal entered and output the optical signal to a receiver; and a wavelength detection unit configured to detect the wavelength of an optical signal by using each of a plurality of optical detectors, determine the passage target optical switch based on a detection result, and output, to the determined passage target optical switch, a control signal for controlling the passage target optical switch so as to enter the passage state, the optical detectors being respectively provided on different paths that are different from the paths on which the plurality of optical switches are provided and that respectively correspond to wavelengths into which the optical signal is split by a wavelength multiplexer/demultiplexer.

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.

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 optical reception device including: a wavelength selection unit configured to split an optical signal amplified by an optical amplifier into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer, and control a passage state of a passage target optical switch through which the optical signal is to be passed, out of a plurality of optical switches provided on the respective paths, to select an optical signal of a path where the optical signal entered and output the optical signal to a receiver; and a wavelength detection unit configured to detect the wavelength of an optical signal by using each of a plurality of optical detectors, determine the passage target optical switch based on a detection result, and output, to the determined passage target optical switch, a control signal for controlling the passage target optical switch so as to enter the passage state, the optical detectors being respectively provided on different paths that are different from the paths on which the plurality of optical switches are provided and that respectively correspond to wavelengths into which the optical signal is split by a wavelength multiplexer/demultiplexer.

Radiation receiver apparatus with a radiation receiver and a radiation entrance face, wherein the radiation receiver includes an active region that detects radiation with a target wavelength in the near-infrared, an optical element is arranged between the radiation entrance face and the radiation receiver, an optical axis of the optical element extends through the radiation receiver, the optical element is shaped and arranged relative to the radiation receiver such that, of radiation incident on the radiation entrance face at an angle of greater than or equal to 40° to the optical axis, at most 10% is incident on the radiation receiver, and a visible light filter is formed between the radiation receiver and the radiation entrance face.

A self-equalizing photo-detector (SEPD) includes, in part, a multitude of optical splitters and photo detectors, and at least one optical delay element. The first optical splitter splits an optical signal into second and third optical signals. The optical delay element delays the second optical signal to generate a fourth optical signal. The second optical splitter splits a signal representative of the fourth optical signal to generate fifth and sixth optical signals. The first photo detector receives the third optical signal via a first optical path, has an anode terminal coupled to an output terminal of the detector and a cathode terminal coupled to a first supply voltage. The second photo detector receives the sixth optical signal via a second optical path, has an anode terminal coupled to a second supply voltage and a cathode terminal coupled to the output terminal of the detector.

A first resistor connected in parallel to a semiconductor optical modulator having first ends, the first resistor and first ends connected to a reference potential. A first end of a first transmission line is connected to second ends of the semiconductor optical modulator and the first resistor. A second transmission line is connected in series to the first transmission line and has an impedance lower than that of the first resistor. A first end of the second transmission line is connected to a second end of the first transmission line. A third transmission line is connected in series to the first and second transmission lines and has an end connected to a second end of the second transmission line, and has an impedance equal to that of the first transmission line. A second resistor and a capacitor are connected in series between the third transmission line and the reference potential.

A wavelength-tunable optical filter control apparatus in an optical access system that uses wavelength-multiplexed optical signal of a plurality of wavelength channels includes a wavelength-tunable optical filter configured to pass an optical signal of a specific wavelength channel among the plurality of wavelength channels; a light receiving element configured to convert the optical signal that has passed through the wavelength-tunable optical filter into an electrical signal; a signal quality determining unit configured to determine a quality of the electrical signal; and a wavelength-tunable optical filter control unit configured to acquire a light intensity of the electrical signal and control a wavelength of the wavelength-tunable optical filter based on the acquired light intensity and a determination result of the quality of the electrical signal.