Provided are a method and system for allocating wavelength channels in a Passive Optical Network (PON), and an Optical Line Terminal (OLT). In the method, an OLT may acquire pre-set wavelength channel priority information and Optical Network Unit (ONU) priority information; and the wavelength channel priority information and the ONU priority information may be sent to each ONU to enable each ONU to selectively access a corresponding wavelength channel according to the wavelength channel priority information and the ONU priority information based on a pre-set rule.

A distributed antenna system (DAS) includes a master unit; a plurality of remote units communicatively coupled with the master unit and distributed to provide coverage within a service area, each of the remote units remotely located from the master unit and other remote units; a coupler element coupled to receive a plurality of MIMO signals, the MIMO signals including first and second MIMO signals, the coupler element configured to: introduce a phase shift in a first portion of the first MIMO signal to generate a first phase shifted portion of the first MIMO signal; combine the first phase shifted portion with a second portion of the second MIMO signal to generate a combined MIMO signal; and present the combined MIMO signal at a first output port of the coupler element; at least one antenna coupled with each remote unit and configured to receive the combined MIMO signal for transmission.

An electro-optical link is provided. In an example embodiment, the electro-optical link includes a number of vertical cavity surface emitting lasers (VCSELs); one or more drivers that operate the VCSELs such that each of the VCSELs selectively emits an optical signal; one or more multiplexers that multiplex a number of optical signals into an optical fiber, each optical signal emitted by one of the VCSELs; and one or more optical fibers. At least two optical signals are multiplexed into each optical fiber of the one or more optical fibers. In some example configurations eight or sixteen optical signals are multiplexed into one optical fiber.

An optical line terminal includes an optical comb generator, N downlink channels D.sub.k, and N uplink-photodetectors PD.sub.k. The optical comb generator is configured to generate a carrier signal having an optical-frequency-comb spectrum and including N optical tones T.sub.k and N optical tones R.sub.k, k={1, 2, . . . , N}. Each of the N downlink channels D.sub.k is optically coupled to the optical comb generator and is configured to generate a respective downlink signal DS.sub.k that includes optical tone T.sub.k modulated by downlink data. Each of the N uplink-photodetectors PD.sub.k is configured to receive a respective one of a plurality of modulated uplink signals US.sub.k, having optical tone R.sub.k as a carrier signal.

A wavelength tuning method and a related device, the method including receiving, by a remote optical module, a wavelength control signal from a central office terminal, where the wavelength control signal indicates a target wavelength tuned by the remote optical module, and where the wavelength control signal is loaded into a first optical service signal in a pilot tone manner, and tuning, by the remote optical module, an operating wavelength of the remote optical module based on the wavelength control signal.

Photonic devices, photonic integrated circuits, optical elements, and techniques of making and using the same are described. A photonic device includes an input region adapted to receive an optical signal including a multiplexed channel characterized by a distinct wavelength, a dispersive region optically coupled with the input region to receive the optical signal, the dispersive region including a plurality of sub-regions defined by an inhomogeneous arrangement of a first material and a second material, and a plurality of output regions optically coupled with the input region via the dispersive region. The plurality of sub-regions can include an input channel section, one or more coupler sections, and one or more branching sections. The plurality of sub-regions together can configure the photonic device to demultiplex the optical signal and to isolate the multiplexed channel at a first output region of the plurality of output regions.

Provided are a next generation in-building relay system and method. The system includes: a 5G signal providing unit configured to down-convert a millimeter wave radio frequency signal to an intermediate frequency signal; a 5G master hub unit configured to convert the intermediate frequency signal into a radio over fiber (RoF) signal and transmit the RoF signal; an optical coupling unit configured to couple a digital optical signal output from a master hub unit and the analog optical signal output from the 5G master hub unit and transmit the coupled signal to an optical cable; and an optical distribution unit configured to separate the digital optical signal and the analog optical signal from the coupled signal, transmit the digital optical signal to a remote optical relay unit, and transmit the analog optical signal to distributed remote units.

A plurality of optical signals are arranged on optical frequency grids having a frequency spacing of ?f, a wavelength multiplexing optical signal includes at least one specific arrangement signal group, and the specific arrangement signal group includes Q S signal(s) and R P signal(s), where Q is an integer of 1 or more and R is an integer of 1 or more. A frequency difference between any pair of S signals included in the specific arrangement signal group is different from frequency differences between all of other pairs of S signals and frequency differences between all pairs of P signals, and a frequency difference between any pair of P signals included in the specific arrangement signal group is different from frequency differences between all pairs of S signals and frequency differences between all of other pairs of P signals.

Photonic devices, photonic integrated circuits, optical elements, and techniques of making and using the same are described. A photonic device includes an input region adapted to receive an optical signal including a multiplexed channel characterized by a distinct wavelength, a dispersive region optically coupled with the input region to receive the optical signal, the dispersive region including a plurality of sub-regions defined by an inhomogeneous arrangement of a first material and a second material, and a plurality of output regions optically coupled with the input region via the dispersive region. The plurality of sub-regions can include an input channel section, one or more coupler sections, and one or more branching sections. The plurality of sub-regions together can configure the photonic device to demultiplex the optical signal and to isolate the multiplexed channel at a first output region of the plurality of output regions.

An optical network including a plurality of gateway nodes interconnected with a plurality of intermediate nodes with segments of fiber. The network includes a plurality of devices, such as reconfigurable optical add drop multiplexers, optimally placed at various nodes throughout the network. The device placement is optimized with an integer linear programming analysis considering span definition such that any given span involves some number of segments not exceeding a number of segments that would require wavelength regeneration, cost of placement of a device at a given node, cost of wavelength regeneration, and various parameters and constraints.