A transmission device including: a signal power detection circuit that detects signal power of a wavelength-division-multiplexed optical signal to be transmitted to a transmission line into which pumping light is inputted from a Raman amplifier; a variable optical attenuator that attenuates the wavelength-division-multiplexed optical signal; and a control circuit that reduces an attenuation amount of the variable optical attenuator depending on an increase in the signal power.

Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, λ.sub.S, based on the measured EMB at a first reference measurement wavelength, λ.sub.M. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive user data and provide electrical signals based on the data; and a modulator operable to modulate the optical signal to provide optical subcarriers based on the electrical signals. A first one of the subcarriers carriers carries first TDMA encoded information and second TDMA encoded information, such that the first TDMA encoded information is indicative of a first portion of the data and is carried by the first one of the subcarriers during a first time slot, and the second TDMA encoded information is indicative of a second portion of the data and is carried by the first one of the subcarriers during a second time slot. The first TDMA encoded information is associated with a first node remote from the transmitter and the second TDMA encoded information is associated with a second node remote from the transmitter. A second one of the subcarriers carries third information that is not TDMA encoded, the third information being associated with a third node remote from the transmitter. A receiver and system also are described.

A multi-level optical signal is sampled to generate an eye diagram. The signal can be adjusted when eyes in the eye diagram have different heights. More specifically, a first value is determined, and the height of a first eye is adjusted using the first value. The first value is multiplied by a stored factor to produce a second value, and the height of a second eye is adjusted using the second value, and so on for other eyes. As a result, eye heights are the same. Similarly, optical power levels of the signal can be adjusted when the levels are not equally spaced. As a result, the optical power levels are equally spaced.

Provided are techniques, devices and systems that enable updating of a reportable parameter table database when a reconfigured optical communication path is formed by switching performed by a branching unit in an undersea optical communication transmission system. A processor may obtain system attributes of each respective segment of a number of segments of the reconfigured optical communication path from a first end point to a second endpoint. The system attributes of each respective segment of the number of segments may be evaluated from the first end point to the second endpoint of the reconfigured optical communication path. A reportable parameter table may be generated based on the evaluated system attributes that includes a listing of operational and structural parameters of system from the first endpoint to the second endpoint of the reconfigured optical communication path.

Techniques for identifying sources of degradations within a PON include detecting a degradation pertaining to a segment of the PON and comparing the drift over time of an optical profile of the segment with respective drifts over time of optical profiles of one or more other PON segments, where pairs of segments share respective common endpoints and an optical profile of a segment corresponds to the characteristics of optical signals delivered over the segment (e.g., attenuation, changes in frequencies, changes in power outputs, etc.). The differences between the compared drift(s) over time are utilized to narrow down the candidate components (e.g., segment endpoints, optical fibers, etc.) for the source of the degradation, and may be utilized to particularly identify a particular endpoint or optical fiber as being the source. The source of the degradation may or may not be a component of the segment to which the degradation pertained.

Chromatic dispersion compensation is performed in one or more pluggable optical transceiver (POT) devices operating within an intensity-modulated direct-detection (IMDD) optical network. Compensation is performed within each POT using an electrical and/or optical chromatic dispersion module which are controlled by a set of parameters. A network computing device includes a computer processor and a host management interface for communicating with the POT. In the event of a link failure, the computer processor determines a second set of parameters to control the one or more dispersion compensation module(s) of the POT. The second set of parameters are different from a first set of parameters used to control the one or more compensation module(s) in the case of a first optical path. The computer processor causes the POT to use the second set of parameters in place of the first set of parameters.

An apparatus for determining a wavelength and a power of an input signal is described. The apparatus comprises a memory which stores instructions, which when executed by the processor, cause the processor to: recover a first phase for a first Mach-Zehnder Interferometer MZI; recover a second phase for a second MZI; subtract the first phase from the second phase to provide a phase difference; determine an unwrapped phase difference as a function of wavelength; determine a coarse wavelength; and determine a first wavelength for the first FSR and a second wavelength from the second FSR; and average the first and second wavelengths to determine the wavelength of the input signal.

An optical wavelength multiplexing transmission device includes: a demultiplexer configured to demultiplex a wavelength multiplexing signal for each wavelength band from a multiplexed signal that includes wavelength multiplexing signals in a plurality of the wavelength bands; a processor configured to detect an optical power value of each wavelength multiplexing signal for each wavelength band; calculate a compensation amount used to compensate a tilt of the wavelength multiplexing signal, by using the optical power value and a predetermined calculation expression; and compensate the tilt of the wavelength multiplexing signal, based on the compensation amount; and a multiplexer configured to multiplex each wavelength multiplexing signal compensated by the processor and output the wavelength multiplexing signal to a transmission line.

A detection system includes: a signal output unit configured to output, to a measurement target, a measurement signal that exhibits a predetermined temporal change; a signal measurement unit configured to measure a response signal, to the measurement signal, from the measurement target; a calculation unit configured to calculate an impulse response of the measurement target, based on a measurement result of the response signal measured by the signal measurement unit; and a detection unit configured to detect abnormality regarding the measurement target, based on the impulse response calculated by the calculation unit.