A wavelength multiplexing communication system includes a master station apparatus and a plurality of slave station apparatuses. The master station apparatus includes a wavelength multiplexing communication unit. The wavelength multiplexing communication unit performs wavelength multiplexing communication with the plurality of slave station apparatuses by using optical signals having the number of wavelengths equal to or less than the number of the plurality of slave station apparatuses. The slave station apparatus includes an optical communication unit. When the main signal communication is performed in the host slave station apparatus, the optical communication unit communicates with the master station apparatus by an optical signal having the same wavelength as a wavelength used by another slave station apparatus in which a main signal notification is not performed.

In a case where a failure occurs in a part of an optical fiber in an optical cable, when attempting to switch to a redundant configuration, the stable use of an optical transmission system is impaired, so that the wavelength band cannot be used effectively. Accordingly, the optical transmission system of the present invention includes a first optical device configured to change the transmission line of a wavelength band signal propagating through a first optical transmission line to a second optical transmission line that is the same path as the first optical transmission line, in the stage before a faulty part in the first optical transmission line, and a second optical device configured to change the transmission line of the wavelength band signal from the second optical transmission line to the first optical transmission line, in the stage after the faulty part.

The method includes sending a first frame of a first modulation format that is suitable for a first group of receivers before sending a second frame of a second modulation format that is suitable for a second group of receivers, wherein the first modulation format is a higher modulation format than the second modulation format, and wherein the method further includes inserting into the first frame at least one symbol of the second modulation format at at least one outer edge of the first frame.

An optical switching apparatus includes an input port, a dispersion component, a first filter, a redirection component, and output ports. The input port enables a first and a second beam to be incident onto the dispersion component, which decomposes the first and the second beams respectively into a plurality of first and second sub-beams, where the plurality of first sub-beams and second sub-beams belong to different bands. The first filter separates transmission directions of the plurality of first and second sub-beams into different transmission directions in a first direction (X) based on the different bands, enables the plurality of first and second sub-beams respectively to be incident onto a first area and a second area of the redirection component, where the first and second areas are separated in the first direction.

Devices, systems and methods for encoding information using optical components are described. Information associated with a first optical signal (e.g., an optical pump) is encoded onto the phase of a second optical signal (e.g., an optical probe) using cross phase modulation (XPM) in a non-linear optical medium. The optical signals are multiplexed together into the nonlinear optical medium. The probe experiences a modified index of refraction as it propagates through the medium and thus accumulates a phase change proportional to the intensity of the pump. The disclosed devices can be incorporated into larger components and systems for various applications such as scientific diagnostics, radar, remote sensing, wireless communications, and quantum computing that can benefit from encoding and generation of low noise, high resolution signals. Examples of the encoded information includes intrinsic noise from the optical source, or others signals of interest, such as electrical, optical, X-ray, or high-energy particle signals.

A method to determine the types of optical fibers forming a link of an optical communication network. By scanning a signal's bit error rate at a receiver end, as a function of a pre-dispersion applied to a signal at a transmitter end, local minimums in the curve indicate the presence of amplifiers, and therefore fiber span extremities. By determining the accumulated dispersion at each fiber extremity, a ratio of dispersion per span length can be obtained and the span's coefficient of chromatic dispersion be inferred, thereby identifying the type of fiber. Alternatively, a signal's signal-to-noise ratio can be scanned, instead of its bit error rate. In a typical network, the required instrumentation is pre-existing.

A system for routing signals in a Distributed Antenna System (DAS) includes one or more local Digital Access Units (DAUs) located at a local location and one or more remote DAUs located at one or more remote locations. Each of the one or more local DAUs includes an optical port coupled to an upstream unit. The upstream unit includes at least one of a repeater, a baseband unit, a Base Transceiver Station (BTS), or a DAU. The one or more remote DAUs are coupled to the one or more local DAUs via one or more optical cables. A distance between the local location and each of the one or more remote locations is greater than two kilometers.

An optical module for transmitting data from a data center via a dense wavelength division multiplex (DWDM) grid includes an optical modulator, a multiplexer, and a transmitter. The optical modulator modulates first and second optical signals pulse amplitude modulation for transmission over first and second wavelengths, respectively. The first wavelength is separated from the second wavelength according to a spacing of the DWDM grid for transmitting data at a selected baud rate. The multiplexer multiplexes the modulated first and second optical signals into a multiplexed optical signal, which includes the modulated first optical signal having the first wavelength and the modulated second optical signal having the second wavelength, and outputs the multiplexed optical signal. A transmitter transmits the multiplexed optical signal via the DWDM grid at the selected baud rate.

An optical module for transmitting data from a data center via a dense wavelength division multiplex (DWDM) grid includes an optical modulator, a multiplexer, and a transmitter. The optical modulator modulates first and second optical signals pulse amplitude modulation for transmission over first and second wavelengths, respectively. The first wavelength is separated from the second wavelength according to a spacing of the DWDM grid for transmitting data at a selected baud rate. The multiplexer multiplexes the modulated first and second optical signals into a multiplexed optical signal, which includes the modulated first optical signal having the first wavelength and the modulated second optical signal having the second wavelength, and outputs the multiplexed optical signal. A transmitter transmits the multiplexed optical signal via the DWDM grid at the selected baud rate.

An optical receiver includes an optical amplifier that amplifies a received optical signal containing multiple wavelengths, a monitor circuit that monitors light intensities of the demultiplexed optical signal, a processor, and a memory having information representing a relationship between a total incident light intensity of the optical signal incident onto the optical amplifier and gains of the optical amplifier for the respective wavelengths. The processor repeats first calculation for determining the gains of the respective wavelengths from the memory, based on a drive current for driving the optical amplifier and an estimation value of the total incident light intensity of the optical signal, second calculation for calculating the incident light intensities of the respective wavelengths of the optical signal based on the gains and the monitored light intensities, and third calculation to calculate the total incident light intensity of the optical signal, until the total incident light intensity converges.