Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, an optical communication system includes a primary transceiver, a component, and secondary transceivers. The primary transceiver is operable to supply first optical subcarriers to an optical communication path, the first optical subcarriers being amplitude modulated at a first frequency to carry first control information and amplitude modulated at a second frequency to carry second control information. The component is operable to be coupled to the optical communication path and includes circuitry operable to detect the first control information. The secondary transceivers are coupled to a terminal end of the optical communication path. At least one of the secondary transceivers is operable to detect the second control information and block the first control information.

A device. At least some example embodiments are a device including a filter element configured to receive optical energy from a first optical fiber. The filter element is reflective in a preselected band of optical wavelengths. A first lens is configured to receive optical energy transmitted through the filter element. A shell is disposed about the optical filter and the first lens; surfaces of the first lens, the filter element and the shell form a first boundary portion of an internal volume of an interior of the shell. A fluid is sealably disposed within the internal volume.

An object is to provide an optical communication system and an optical communication method that are capable of, when assigning wavelengths on a per-service basis and providing services on a per-area basis, preventing degradation of signal quality due to linear crosstalk and preventing an increase in cost and size. An optical communication system according to the present invention includes an optical splitter 300 connecting N first ports and M second ports by a combination of 2×2 fiber optical splitters, N and M each being an integer of two or more, where wavelengths of optical signals to be received are limited for each group of optical receivers 106, by using a correlation between a fused extension length of at least one 2×2 fiber optical splitter directly connected to the first port, among the 2×2 fiber optical splitters, and wavelength output characteristics of the second port of the optical splitter 300.

Techniques for creating a design for a physical device are disclosed. A computing system receives a design specification. The design specification includes a design region, one or more ports, and a port location perimeter. The computing system determines an initial proposed design based on the design specification that includes the design region and a location for each port of the one or more ports within the port location perimeter. The computing system optimizes the design region of the initial proposed design to create an improved design region, and optimizes at least one location of a port of the one or more ports within the port location perimeter to create an improved proposed design.

A wavelength selective switch includes an optical fiber array, a multiplexing/demultiplexing component, and a transmission direction adjustment component. The optical fiber array includes a first optical fiber and at least one second optical fiber. The first offset is used to compensate for a second offset of a diffraction spectrum generated when a plurality of single-wavelength optical signals obtained after an optical input signal is processed by the multiplexing/demultiplexing component arrive at the transmission direction adjustment component, so that the second offset of the diffraction spectrum of the plurality of single-wavelength optical signals arriving at the transmission direction adjustment component is 0 or may be ignored. An optical system has a simple structure, and no optical element needs to be added. This increases optical design freedom, facilitates optical path system commissioning, and reduces reliability risks and costs of subsequent products.

A wavelength division multiplexing filter comprises: a first multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers, and a second multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers; wherein the first multi-order Mach-Zehnder interferometer and the second multi-order Mach-Zehnder interferometer are included in a group of multiple multi-order Mach-Zehnder interferometers arranged within a binary tree arrangement, the binary tree arrangement comprising: a first set of a plurality of multi-order Mach-Zehnder interferometers, the first set including the first multi-order Mach-Zehnder interferometer, and having an associated spectral response with a first spacing between adjacent passbands, and a second set of at least twice as many multi-order Mach-Zehnder interferometers as in the first set, the second set including the second multi-order Mach-Zehnder interferometer, and having an associated spectral response with a second spacing between adjacent passbands that is twice the first spacing.

Provided here are: a mounting section having a light-emitting element for emitting an optical signal; a mounting section arranged alongside the mounting section and having a light-emitting element for emitting an optical signal that is different in wavelength from the optical signal; and an optical multiplexer having a filter for transmitting therethrough only the wavelength of the optical signal, a mirror for reflecting the optical signal transmitted through the filter, and a filter arranged alongside the filter, for transmitting therethrough only the wavelength of the optical signal, and for reflecting the optical signal reflected by the mirror and multiplexing it with the transmitted optical signal; wherein the light-emitting element is mounted in the mounting section to be displaced toward the light-emitting element from a center in a width direction across an emission direction of the optical signal.

A system including wavelength multiplexers. In some embodiments, the system includes: a first multiplexing element, having a first plurality of input waveguides, each configured to receive light at a respective wavelength of a first plurality of wavelengths; and a second multiplexing element, having a second plurality of input waveguides, each configured to receive light at a respective wavelength of a second plurality of wavelengths. A wavelength of the second plurality of wavelengths may fall between a first wavelength of the first plurality of wavelengths and a second wavelength of the first plurality of wavelengths.

A waveguide division multiplexer and demultiplexer includes a first-stage Mach-Zehnder interferometer (MZI) and two second-stage MZIs. The first-stage MZI includes two input ends and two output ends, in which one of the inputs is configured to receive an input optical beam with a first center wavelength and a second center wavelength, and the output ends are configured to respectively transmit first-stage output optical beams respectively with the first center wavelength and the second center wavelength. One input terminals of the second-stage MZI are configured to respectively receive the first-stage output optical beams, and one output terminals of the second-stage MZI are configured to transmit second-stage output optical beams with the first and second center wavelengths, respectively. Each second-stage MZI is configured in cross-state condition.

A delivery fiber assembly suitable for delivering broad band light and including a delivery fiber and a connector member. The delivery fiber has a length, an input end for launching light, and a delivery end. The delivery fiber includes along its length a core region and a cladding region surrounding the core region, the cladding region includes a cladding background material having a refractive index N.sub.bg and a plurality of microstructures in the form of inclusions of solid material having refractive index up to N.sub.inc and extending in the length of the longitudinal axis of the delivery fiber, wherein N.sub.inc<N.sub.bg. The plurality of inclusions in the cladding region is arranged in a cross-sectional pattern including at least two rings of inclusions surrounding the core region. The connector member is mounted to the delivery fiber at a delivery end section of the delivery fiber including the delivery end.