A bi-directional multiplexer/demultiplexer comprises a common port, an upgrade (UPG) port, a plurality of input/output ports, a plurality of wavelength division multiplexing (WDM) filters arranged in a zig-zag fashion, and a single bi-directional tap. The single bi-directional tap directs a tapped signal to a demultiplexing tap port in demultiplexing mode and a multiplexing tap port in multiplexing mode. The bi-directional tap may be a thin-film tap filter.

A photonic integrated circuit (PIC) is grown by epitaxy on a substrate. The PIC includes at least one active element, at least one passive element, and a dielectric waveguide. The at least one active and passive elements are formed over the substrate and are in optical contact with each other. The dielectric waveguide is formed over the substrate, and is in optical contact with the at least one active and passive elements. The at least one active and passive elements each are formed using a III-V compound semiconductor material.

The present disclosure provides a method and related products. The method includes: performing distribution matching on a first bit sequence to obtain a second bit sequence; obtaining at least two candidate bit sequences for the second bit sequence, where each of the at least two candidate bit sequences includes a first bit part for identifying the candidate bit sequence and a second bit part obtained based on interleaving of the second bit sequence; determining a third bit sequence in the at least two candidate bit sequences for channel coding. In this way, distribution matching needs to be performed simply once for the first bit sequence while obtaining at least two candidate bit sequences for the second bit sequence, which can reduce redundant processing and improve overall system efficiency.

Provided is a network node for a coherent optical wavelength division multiplex (WDM) transmission network including at least one remote port which is adapted to receive from and/or output to neighboring network nodes an optical WDM signal including one or more optical channel signals each lying within an optical channel of an optical WDM transmission band and a predetermined number N of local ports, each local port being adapted to receive from a dedicated coherent optical transmitter an optical add channel signal which is to be integrated in an optical WDM signal that is output at a remote port and/or each local port being adapted to output to a respective dedicated optical receiver an optical drop channel signal. The network node includes an optical router device that defines the at least one remote port and further defines an internal remote port, the optical router device being configured to route one or more selected or all optical channel signals included in the optical WDM signal received at a selected remote port as optical drop channel signals to the internal remote port and/or to route one or more optical add channel signals received at the internal remote port to one or more selected remote ports or to all remote ports. The network node further includes a passive optical filter device which is connected, at an internal remote port of the passive optical filter device, to the internal remote port of the optical router device, and which further defines the predetermined number N of local ports. The passive optical filter device is configured to define N optical bandpass filter functions each of which describes a bandpass filter characteristic between the internal remote port of the passive optical filter device and a selected, respectively differing local port. The passband of each optical bandpass filter function covers two or more neighboring optical channels. The passbands of all optical bandpass filter functions differ from each other with respect to the optical channels covered.

Systems and methods of capacity changes in an optical network having a plurality of optical sections include, responsive to a request for a capacity change for a plurality of channels, bundling the plurality of channels into different steps such that all of the plurality of channels are assigned to a step of the different steps; and causing implementation of the different steps across the plurality of optical sections, wherein each section performs the implementation and the bundling between corresponding Optical Add/Drop Multiplexer (OADM) nodes independently and asynchronously from one another.