Provided are a monitoring device, a monitoring method, an optical amplifier, and an optical transmission system that are adapted for an increase in the number of cores in a multi-core optical fiber transmission path, and that are suitable for crosstalk monitoring. The monitoring device monitors a multi-core optical fiber transmission path comprising a plurality of use core and at least one or more non-use cores. The monitoring device comprises: an applying means for applying dithering to signal light propagating in the use cores; a monitoring means for monitoring the power of the non-use cores; and a separating means for separating a monitoring result from the monitoring means into power components from the plurality of use cores.

This application relates to the field of fiber-optic communication technologies, and provides a fault locating method, apparatus, and system. The method includes: obtaining a first correspondence between a receive time and receive power during reverse backhaul that occurs when a test optical signal that can be reflected by a reflection component disposed at each port of at least one stage of optical splitter is in downlink transmission in an ODN, where reverse backhaul includes backscatter and reflection or includes backscatter; determining, based on the first correspondence, a second correspondence between a transmission distance and receive power during reverse backhaul that occurs when a test optical signal is in downlink transmission in an optical fiber between each port of the at least one stage of optical splitter and a component connected to the port; and locating a fault in the ODN based on the second correspondence.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.

Methods and systems for reducing power consumption in a multi-channel passive optical network (PON). A processor in the PON may monitor the channels in the multi-channel PON to detect a currently inactive channel, determine whether the detected channel has been inactive for an extended period of time, and deactivate the detected channel (by deenergizing transmitter(s) and/or receiver(s) associated with the detected channel) in response to determining that the channel has remained inactive for an extended period of time. The processor may re-activate the channel in response to determining that an optical signal has been reliably present on the channel for a sufficient period of time.

Methods and systems for reducing power consumption in a multi-channel passive optical network (PON). A processor in the PON may monitor the channels in the multi-channel PON to detect a currently inactive channel, determine whether the detected channel has been inactive for an extended period of time, and deactivate the detected channel (by deenergizing transmitter(s) and/or receiver(s) associated with the detected channel) in response to determining that the channel has remained inactive for an extended period of time. The processor may re-activate the channel in response to determining that an optical signal has been reliably present on the channel for a sufficient period of time.

Techniques for maintaining equipment of a PON include determining a current optical profile for each segment of a plurality of segments of a PON, and detecting that the current optical profile of a particular segment is outside of a designated operating range. Based on the detection, drifts over time of the optical profile of the segment and of optical profiles of one or more other segments that share respective common endpoints with the segment are determined and compared, and based on the comparison, a component of the PON (e.g., an endpoint or an optical fiber) is identified as requiring maintenance. Each segment's optical profile corresponds to characteristics of optical signals delivered over the segment (e.g., attenuation, changes in frequencies, changes in power outputs, etc.), and current optical profiles of the PON's segments may be repeatedly updated over time to continuously monitor for components that need maintenance.

An apparatus includes a reconfigurable optical add/drop multiplexer (ROADM) having an input port to receive a first optical signal from a second device. The ROADM also includes a first wavelength selective switch (WSS), in optical communication with the input port, to convert the first optical signal into a second optical signal, a loopback, in optical communication with the first WSS, to transmit the second optical signal, and a second WSS, in optical communication with the loopback, to convert the second optical signal to a third optical signal and direct the third optical signal back to the second device via the input port.

A function of detecting an unused path through which actual data is not transmitted in a long-distance redundant network is realized at low cost. In an optical transmission system 20, each of the optical transceivers 21a and 21b that are connected to each other by an optical fiber cable 22 and disposed separately includes a protocol IC unit 35. The protocol IC unit 35 transmits an idle signal A1 with empty data using an optical signal P1 to an unused path of the optical fiber cable 22. At the time of this transmission, the protocol IC unit 35 outputs, to the transmission unit 33, a control signal C1 for performing, at a fixed modulation period, ON/OFF modulation on the optical signal P1 on which the idle signal A1 is superimposed. Also, the protocol IC unit 35 transmits an OAM signal O1 at an OAM period that is a period different from a modulation period, and performs control to turn ON the control signal C1 at the time of this transmission. The protocol IC unit 35 performs control to set the QAM period T2 as a period longer than or equal to a plurality of modulation periods T1. The transmission unit 33 is configured to perform ON/OFF modulation on the optical signal P1 using the control signal C1, and transmits the modulated optical signal P1.

There are provided a communication device, a communication system, and a communication method. A communication device includes a first receiver configured to receive a data signal and generate a level control signal based on an initial level of the data signal and on an error rate of the data signal; and a transmitter configured to transmit the level control signal.

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.