There is provided an optical signal monitoring device and an optical signal monitoring system of a wavelength division multiplexing based network including: an input unit configured to receive each of downlink signals and uplink signals; a wavelength division multiplexing filter configured to separate the downlink signals and the uplink signals by wavelength; an optical power measurement module configured to measure optical power of each signal separated by wavelength; and a controller configured to determine whether an optical signal is abnormal based on optical power information measured by the optical power measurement module.

The present application discloses an add/drop multiplexer, including a first line board and a tributary board, where the first line board includes at least a first interface and a second interface, the first interface is disposed between the tributary board and the first line board, and the second interface is disposed on a network side of the first line board; the first line board is configured to output a first signal received from a first link through the second interface; the first line board is configured to output a second signal received from the first link to the tributary board through the first interface; and the first line board is configured to receive a third signal from the tributary board through the first interface, and input the third signal into the first link. An inter-board interface on a link is effectively eliminated, thereby improving a link bandwidth of a device.

A wavelength division multiplexer/demultiplexer, a photonic integrated chip, and an optical module are provided. The wavelength division multiplexer/demultiplexer includes a substrate, a bus waveguide provided on the substrate, and at least two wavelength division multiplexing/demultiplexing units provided on the bus waveguide. Each of the at least two wavelength division multiplexing/demultiplexing units includes a mode multiplexer and an asymmetric Bragg grating. The mode multiplexer includes a first port, a second port, and a third port. The third port is connected to the asymmetric Bragg grating, so as to input a light in a TE1 mode or a higher-order mode to the asymmetric Bragg grating. The asymmetric Bragg grating transmits light containing wavelengths other than a wavelength i. A grating period of the asymmetric Bragg grating and the wavelength i satisfy a resonance condition.

Wavelength division multiplexers for space division multiplexing can include wavelength division multiplexing fanout devices or pump-signal combiners for multicore fibers.

An optical filter comprising a first distributed Bragg reflector (DBR) layer, a second DBR layer, and an intrinsic semiconductor layer positioned between the first DBR layer and the second DBR layer, with the intrinsic semiconductor layer providing a passband wavelength for the optical filter based on a carrier density of the intrinsic semiconductor layer.

Example embodiments of the present invention relate to An optical node comprising of at least two optical degrees; a plurality of directionless add/drop ports; and at least one wavelength equalizing array, wherein the at least one wavelength equalizing array is used to both select wavelengths for each degree, and to perform directionless steering for the add/drop ports.

Techniques for communications using optical fiber are disclosed. An optical add/drop multiplexer (OADM) node includes an interface to a first fiber pair connecting a first trunk station and a second trunk station. The OADM node further includes an interface to a second fiber pair connecting the first trunk station and the second trunk station with a branch station. The OADM node includes a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station. Other embodiments are described and claimed.

A bidirectional optical tap-monitor is described for detecting an optical signal power carried by a through waveguide. The tap-monitor comprises a tap waveguide placed near the through waveguide, and a single waveguide-type photodetector for detecting a fraction of the optical signal power coupled from the tap waveguide. The tap waveguide includes two ports at opposite ends of the tap waveguide and the waveguide-type photodetector includes two ports that are connected respectively to the two ports of the tap waveguide. When light travels through the through waveguide in one direction, the coupled fraction of the optical signal power is fed to the photodetector via one of the two ports of the tap waveguide, and when light travels through the through waveguide in the opposite direction, the coupled fraction of the optical signal power is fed to the photodetector via the other one of the two ports of the tap waveguide. The bidirectional optical tap-monitor is operable in either a forward-propagating or a backward-propagating direction.

Wavelength division multiplexing technology in which a layer of arrayed waveguides is used to extend the number of ports of wavelength selective switches used in multiplexing and/or demultiplexing the optical signals transported over the optical network. In some examples, the wavelength division multiplexing technology is used as part of an optical signal communication system, such as between data centers or as part of a larger network.

In order to allow for a flexible network configuration and establish an alternative path without performing communication between optical branching units in the event of a failure on a path in an optical communication system to which a plurality of optical branching units are connected, the optical branching unit includes optical add-drop unit for outputting an input WDM signal to any of a plurality of paths on a per-wavelength basis, light wavelength detecting unit for detecting a wavelength of the input WDM signal, a wavelength database storing, on a per-wavelength basis, information about sections through which optical signals contained in the WDM signal pass, and control unit for changing a setting of the optical add-drop unit so that a path of an optical signal of a wavelength passing through a particular one of the sections bypasses the particular section when all wavelengths stored in the wavelength database are not detected in the particular section by the light wavelength detecting unit.