An electrode structure includes: a metal film with an opening formed in a part of the metal film; and a transparent conductive film disposed in the opening, wherein the transparent conductive film is electronically connected to an element and overlaps with the element as viewed in a plan view in a thickness direction of the transparent conductive film.

A test apparatus has at least one optical source, a high-speed photodetector, a microcontroller or processor, and electrical circuitry to power and drive the optical source, high-speed photodetector, and microcontroller or processor. The apparatus measures the frequency response and optical path length of a multimode optical fiber under test, utilizes a reference VCSEL spatial spectral launch condition and modal-chromatic dispersion interaction data to estimate the channels total modal-chromatic bandwidth of the fiber under test, and computes and presents the estimated maximum data rate the fiber under test can support.

Examples described herein relate to a method and a system for removing the common-mode current. The receiver includes a photodetector, a common-mode adjustment circuit, an analog front-end, an eye scan circuit, and a control unit. The photodetector generates an input photocurrent responsive to a received optical signal. The common-mode adjustment circuit generates an adjusted input current based on the input photocurrent. The analog front-end generates a differential voltage based on the adjusted input current. Based on the differential voltage, the eye scan circuit generates an eye scan information defining a first outer eye and a second outer eye in an eye diagram. The control unit tunes the common-mode adjustment circuit based on a relative height metric of a first height of the first outer eye and a second height of the second outer eye to remove a portion of the common-mode current from the input photocurrent.

A high-speed, wavelength-converting receiver that includes a housing; a high-speed, wavelength-converting layer attached to the housing and configured to absorb a first light having a first wavelength range and emit a second light having a second wavelength range, which is different from the first wavelength range; and a high-speed photodetector attached to the housing and having an active face configured to absorb the second light having the second wavelength range and generate an electrical signal. The active face of the photodetector is fully placed within the housing.

A power over fiber system includes a power sourcing equipment, a powered device, an optical fiber cable and a controller. The power sourcing equipment includes semiconductor lasers. The semiconductor lasers output feed light of different wavelengths by oscillating with electric power. The powered device includes photoelectric conversion elements. The photoelectric conversion elements have different photoelectric conversion efficiencies and convert the feed light output from the power sourcing equipment into electric power with their respective photoelectric conversion efficiencies. The optical fiber cable transmits the feed light from the power sourcing equipment to the powered device. The controller performs a process of selecting and activating one of the semiconductor lasers and a process of selecting and activating one of the photoelectric conversion elements in order that the power over fiber system perform predetermined power supply.

A PON system comprising multiple PONs, each having a respective intelligent splitter monitor (ISM). In addition to having a passive optical splitter therein, an ISM also has several remotely powered active components configured to monitor the presence of uplink light signals on the ports of the splitter and communicate with the central office using out-of-band optical signals. These ISM functionalities enable the network operator, e.g., to automatically map PON connectivity, pairing each port on the splitter with a distinct optical network unit. The PON system further comprises an optical module connected to the multiple PONs through an optical switch in a manner that supports shared access to said module by the corresponding multiple ISMs. In an example embodiment, the optical module comprises an optical transceiver capable of communicating with the ISM transceivers and one or more lasers configured to provide high-intensity light for remotely charging the ISM batteries.

Lateral and vertical microstructure enhanced photodetectors and avalanche photodetectors are monolithically integrated with CMOS/BiCMOS ASICs and can also be integrated with laser devices using fluidic assembly techniques. Photodetectors can be configured in a vertical PIN arrangement or lateral metal-semiconductor-metal arrangement where electrodes are in an inter-digitated pattern. Microstructures, such as holes and protrusions, can improve quantum efficiency in silicon, germanium and III-V materials and can also reduce avalanche voltages for avalanche photodiodes. Applications include optical communications within and between datacenters, telecommunications, LIDAR, and free space data communication.

A reception device includes a measurement unit that measures a first number of times for which a first phase and a first reverse phase based on a differential signal obtained by amplifying a signal based on noise intersect with each other, the first reverse phase being a reverse phase of the first phase, an oscillator that transmits a first signal, a comparison unit that compares the first number of times with a predetermined first reference value, and a signal output unit that outputs a second signal indicating that an optical signal has been received when the first number of times and the first reference value coincide with each other. The measurement unit resets the first number of times when the first signal is received.

A power over fiber system includes: a first data communication device including a power sourcing equipment device; a second data communication device including a powered device; and an optical fiber cable. The first data communication device and the second data communication device perform optical communication with one another. The first data communication device is capable of controlling low power supply and high power supply that are performed by the power sourcing equipment device. Feed electric power by the high power supply exceeds feed electric power by the low power supply. The first data communication device starts up the second data communication device by the low power supply to the second data communication device, and enables the high power supply after receiving predetermined light from the second data communication device, and disables the high power supply before receiving the predetermined light.

A cascaded avalanche photodiode (APD) is provided with high responsivity and high saturation current. Single multiplication layer (M-layer) is inserted with multiple field control layers to be cut into several M-layers in different regions. Thus, with the breakdown voltage decreased, the critical field lowered, the saturation power enhanced, and the gain increased, avalanche breakdown effect is achieved.