A relay transmission system includes a relay unit configured to relay uplink signals and downlink signals in the first and second communication systems, a time division duplex (TDD) information estimation unit configured to estimate a transmission period of network devices in the first communication system on the basis of the uplink or downlink signal of the first communication system that is relayed by the relay unit, a surplus bandwidth determination unit configured to determine a surplus bandwidth in which an uplink signal of the first communication system is not allocated to a relay target of the relay unit during the transmission period on the basis of the number of network devices and a maximum transmission capacity of the network devices, and a bandwidth allocation unit configured to allocate the uplink signal of the second communication system to the relay target of the relay unit in the surplus bandwidth.

A colorless mux/demux cable assembly, including a first fiber optic cable, a second fiber optic cable, and a main body that includes an N:1 optical combiner and a 1:N optical splitter. The N:1 optical combiner is configured to combine individual optical signals received by each of N input fibers of the second fiber optic cable and provide a combined output signal to an output fiber of the first fiber optic cable. The 1:N optical splitter is configured to split a combined input optical signal (having N wavelength channels) received via an input fiber of the first fiber optic cable and provide a split output signal comprising each of the N wavelength channels to each of N output fibers of the second fiber optic cable.

A system includes (i) an optical link including multiple spans of optical fiber and multiple network elements and (ii) at least one switch configured to reverse a direction that at least one of the network elements communicates over the optical link.

A bidirectional optical amplifier amplifies optical signals having signal wavelength and signal power input from two directions. The amplifier is arranged so that two counter-propagating signals pass through a first pumped rare earth doped pre-amplifier before passing through other amplifiers downstream. Optical circulators route the two counter propagating signals so that they both pass through in a counter-propagating manner through subsequent pumped rare earth doped amplifiers downstream.

A pluggable bidirectional optical amplifier module may include preamp and booster optical amplifiers and a housing. The preamp optical amplifier may be configured to amplify optical signals traveling in a first direction. The booster optical amplifier may be configured to amplify optical signals traveling in a second direction. The housing may at least partially enclose the preamp optical amplifier and the booster optical amplifier. The pluggable bidirectional optical amplifier module may have a mechanical form factor that is compliant with a pluggable communication module form factor MSA. A colorless mux/demux cable assembly may be operated with the pluggable bidirectional optical amplifier. The colorless mux/demux cable assembly may include a 1:N optical splitter a N:1 optical combiner coupled side-by-side to the 1:N optical splitter, a first fiber optic cable optic cable, and a second fiber optic cable.

Modular kit of the spectrally flexible device for bidirectional transmissions of optical signals sensitive to timing in the Internet and other networks in the basic embodiment contains the source of the optical holding signal, which is electrically bi-directionally interconnected with the control electronics module. This source of the optical holding signal is optically interconnected is optically interconnected by its one output via the first isolator and the first wave-sensitive coupler with one optical input/output of the semiconductor optical amplifier and/or the second output of the source of the optical holding signal is interconnected via the second isolator and the second wave-sensitive coupler with the second optical input/output of the semiconductor optical amplifier. Semiconductor optical amplifier is electrically bi-directionally interconnected with the control electronics module, the input of which is connected to the output of the power supply module.

An amplification method intended for a PON access network, which includes an OLT with multiple ports and with one bidirectional amplifier per port that is shared for the transmission downlink and uplink, at least one ODN connecting a given port of the OLT to a plurality of ONUs and defining a transmission channel, access to the transmission channel for the uplink being of TDMA type and the transmission channel for the downlink being time-shared. The method includes, for a given ODN: receiving bursts from the ONUs, modulating the gain of the amplifier in synchronicity with the received bursts.

An object is to provide a monitoring signal light output apparatus capable of transmitting a monitoring signal light with a simple configuration. An optical demultiplexer (11) is inserted into an optical fiber (F1) and demultiplexes a monitoring signal light (M1) transmitted through the optical fiber (F1). A SOA (13) amplifies and modulates the monitoring signal light (M1) separated by the optical demultiplexer (11). A control unit (15) outputs a signal (Si) indicating a state of a submarine apparatus. A SOA drive unit (14) outputs a drive signal (S2) to the SOA (13) in response to the signal (Si) to perform a modulation operation of the monitoring signal light (M1). An optical multiplexer (17) multiplexes the monitoring signal light (M1) amplified and modulated by the SOA (13) into the signal light transmitted by the optical fiber (F1). The monitoring signal light output apparatus is mounted on the submarine apparatus.