The invention relates to a power-over-fiber (PoF) system, comprising: an optical source configured to generate an optical signal, wherein the optical signal comprises an intensity modulation; an optical fiber configured to receive the optical signal from the optical source and to guide the optical signal; an optical sink, which is configured to receive the optical signal from the optical fiber and to convert the optical signal into an electrical signal; a detection unit, which is configured to detect at least one characteristic of the electrical signal, wherein the characteristic is at least partially caused by the intensity modulation of the optical signal; and a control unit, which is configured to control the optical source based on the detected characteristic.

Example optical devices are described. One example optical device includes a receiver. The receiver includes a photodetector, a first amplifier, a second amplifier, and a controller, where the photodetector is coupled to the first amplifier, the first amplifier is coupled to the second amplifier, and the first amplifier and the second amplifier are separately coupled to the controller. The controller is configured to control a gain of the first amplifier and a gain of the second amplifier based on a preset arrival time of an optical signal and a gain intensity corresponding to the optical signal. The photodetector is configured to receive the optical signal and convert the optical signal into a current signal. The first amplifier is configured to convert the current signal into a first voltage signal. The second amplifier is configured to convert the first voltage signal into a second voltage signal.

An apparatus includes a TDM PON optical transceiver including a direct-detection optical receiver. The direct-detection optical receiver is configured to demodulate data from a temporal segment of a data modulated optical signal, wherein the optical carrier frequency of the segment varies at a rate of, at least, 1 giga-Hertz per second.

A signal processing device processes reception signals of optical signals received by a receiver when the optical signals transmitted from a transmitter are propagated to the receiver via a plurality of paths, and includes: a signal-to-noise ratio calculating unit that calculates signal-to-noise ratios of the optical signals that have been propagated through the respective paths, from propagation distances of the optical signals in the respective paths, intensities of the optical signals transmitted from the transmitter, and intensities of noise with respect to the optical signals transmitted from the transmitter; an amplitude adjusting unit that adjusts amplitudes of the reception signals of the optical signals that have been propagated through the respective paths, using the corresponding signal-to-noise ratios calculated by the signal-to-noise ratio calculating unit; and a signal combining unit that combines the reception signals whose amplitudes have been adjusted by the amplitude adjusting unit.

An optical receiver includes a parasitic current compensation circuit having a reference diode, a sense avalanche photodiode (APD), at least one DC voltage source, and a measurement node. The at least one DC voltage source is configured to generate a first DC bias voltage that varies over time and drives the reference diode, and generates a second DC bias voltage that varies over time and drives the sense APD. A reference parasitic current travels through the reference diode based on the first DC bias voltage. A sense current travels through the sense APD based on the second DC bias voltage and exposure of the sense APD to a light signal. The measurement node receives a sense photocurrent, which is generated by the sense APD in response to the exposure of the sense APD to the light signal, the sense photocurrent including the sense current less the reference parasitic current.

An optical transmission and reception system includes an optical transmitter that converts an electrical data signal into an optical signal and transmits the optical signal; and an optical receiver that receives the optical signal input from the optical transmitter via an optical transmission line and converts the optical signal into the data signal. The optical transmitter includes a first compensator that compensates for a loss generated in the optical transmitter based on a first coefficient and a second coefficient, and the optical receiver includes a second compensator that compensates for a loss generated in the optical transmission line based on a third coefficient.

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.

An autonomous mining system includes a real-time digital video transmission sub-system configured to obtain video streams from underground, and transfer the video streams to a control center located above ground; and an exploration and maintenance sub-system located underground, and configured to extract a resource and bring the resource to the surface, based exclusively on commands received from the control center through the real-time digital video transmission sub-system.

Aspects described herein include an optical apparatus comprising a multiple-stage arrangement of two-mode Bragg gratings comprising: at least a first Bragg grating of a first stage. The first Bragg grating is configured to transmit a first two wavelengths and to reflect a second two wavelengths of a received optical signal. The optical apparatus further comprises a second Bragg grating of a second stage. The second Bragg grating is configured to transmit one of the first two wavelengths and to reflect an other of the first two wavelengths. The optical apparatus further comprises a third Bragg grating of the second stage. The third Bragg grating is configured to transmit one of the second two wavelengths and to reflect an other of the second two wavelengths.

Example optical devices are described. One example optical device includes a receiver. The receiver includes a photodetector, a first amplifier, a second amplifier, and a controller, where the photodetector is coupled to the first amplifier, the first amplifier is coupled to the second amplifier, and the first amplifier and the second amplifier are separately coupled to the controller. The controller is configured to control a gain of the first amplifier and a gain of the second amplifier based on a preset arrival time of an optical signal and a gain intensity corresponding to the optical signal. The photodetector is configured to receive the optical signal and convert the optical signal into a current signal. The first amplifier is configured to convert the current signal into a first voltage signal. The second amplifier is configured to convert the first voltage signal into a second voltage signal.