A reconfigurable optical switch apparatus comprising m input ports, m output ports, k add ports, k drop ports and a switch matrix comprising mk wavelength selective optical switches arranged in m rows and k columns. Each switch comprises first, second, third and fourth ports. The columns are grouped in adjacent pairs, in each pair a first column being connected to a respective drop port on a first side of the switch matrix and each wavelength selective switch in said first column having the fourth port arranged on said first side and a second column, adjacent the first column, being connected to a respective drop port on a second side, opposite the first side, of the switch matrix and each wavelength selective switch in said second column having the fourth port arranged on said second side.

A coherent optical receiver includes: an attenuator that adjusts a power of an input optical signal; a mixer that mixes an optical signal output from the attenuator and local oscillator light; a photo detector that converts an optical signal output from the mixer into an electric signal; an amplifier that amplifies an output signal of the photo detector; a gain controller that controls a gain of the amplifier; a memory that stores dependence information that indicates a relation between an input optical power of an optical signal of a specified wavelength and a gain of the amplifier; and a controller that calculates an input optical power of the target wavelength based on a gain of the amplifier and the dependence information, and controls an attenuation amount of the attenuator based on the calculated input optical power, when a WDM optical signal is input into the coherent optical receiver.

Systems and methods for optical modulation index calibration in a CATV network.

A measuring device includes an identifying unit configured to identify a design value of a central frequency of spectrum of an optical signal for each of sub-channels, the optical signal being formed in Nyquist pulse, the sub-channels forming a super-channel in wavelength division multiplexing communication; and a measurer configured to measure the power of the optical signal in a band for each of the sub-channels, the identified design value of the central frequency of the band being a central frequency of the band, the band being narrower than a frequency band of a corresponding one of the sub-channels.

An optical relay device is provided which is capable of outputting control signal light without equipping a light source for the control signal light and capable of flexibly managing and changing a wavelength of the control signal light in accordance with a state of a network. The optical relay device includes an optical receiving unit that receives a wavelength multiplexed optical signal, a control unit that specifies a first wavelength and outputting notification information, and a processing unit that selects an optical signal having the first wavelength from the received wavelength multiplexed optical signal, applying intensity-modulation in accordance with the notification information to the selected optical signal, adding the intensity-modulated optical signal back to the wavelength multiplexed optical signal, and outputting the wavelength multiplexed optical signal.

An optical transmission apparatus may include a coherent detector, a photoelectric converter, an amplifier, a gain controller, and an optical power monitor. The coherent detector may perform a coherent detection on received light including a plurality of wavelengths to select light having any one of the wavelengths. The photoelectric converter may convert the light having the selected wavelength to an electrical signal. The amplifier may amplify the electrical signal. The gain controller may control a gain of the amplifier depending on an output amplitude of the amplifier. The optical power monitor may calculate an optical power level of the selected wavelength based on the gain and the output amplitude.

A method of optimizing optical signal quality in an optical communications link comprising a plurality of sections each comprising an optical amplification apparatus and an optical fiber span, the method comprising: for each section, determining a respective optimal optical channel power which minimizes a sum of an indication of a respective linear optical noise and an indication of a respective nonlinear optical noise; and generating and transmitting at least one control signal arranged to cause a target optical channel power of each section to be set to the respective optimal optical channel power.

An optical line terminal (OLT) in a time and wavelength division multiplexed (TWDM) passive optical network (PON). The OLT comprises a first optical port, a second optical port, and a processor. The first optical port is configured to couple to a plurality of optical network units (ONUs) via an optical distribution network (ODN). The second optical port is configured to couple to the ONUs via the ODN. The processor is coupled to the first optical port and the second optical port and is configured such that, responsive to receiving information indicating that the first optical port has experienced a greater power loss over time than the second optical port, the OLT assigns to the first optical port a first wavelength with a power greater than the power of a second wavelength assigned to the second optical port.

An optical amplifier (1), and a related optical amplification method, comprising an optical path (2) having an input end (3) and an output end (4), a first erbium doped optical fiber (5) placed along the optical path, a first gain flatting filter (6) placed along the optical path downstream the first erbium doped optical fiber, a second erbium doped optical fiber (7) placed along the optical path downstream the first gain flatting filter, a second gain flatting filter (8) placed along the optical path downstream the second erbium doped optical fiber, a third erbium doped optical fiber (9) placed along the optical path downstream the second gain flatting filter, and an optical pump (10) optically coupled to the optical path so as to optically pump at least the first and the third erbium doped optical fiber.

An optical communication system, a method and a network device for an optical network are provided, wherein the device comprises a first port coupled with a first optical fiber link, a second port coupled with a second optical fiber link, the first port and the second port being configured to be coupled with respect to each other in case of a failure of the first optical fiber link or in case of a failure of the second optical fiber link.