An optical system (100) is described including: a reconfigurable optical device (103) with multiplexing wavelength division, comprising a plurality of actuators (A1-AN) and having associated a number of optical channels (M) and a number of degrees of freedom (N) lower than the number of optical channels; an optical stimulus source (106) connected to said reconfigurable optical device (103) to provide an optical stimulation signal (S.sub.in) having a wavelength band including a plurality of wavelengths associated with the optical channels; an optical-electric conversion device (200) configured to receive from said reconfigurable optical device (103) an optical monitoring signal (S.sub.out) corresponding to the optical stimulation signal (S.sub.in) and to provide a group of electrical signals of intensity (S.sub.EL1-S.sub.ELK) each representative of an intensity of the optical monitoring signal (S.sub.out) evaluated at a relative wavelength included in said band. The system also includes a control device (110) configured to control the plurality of actuators (A1-AN) according to said group of electrical signals (S.sub.EL1-S.sub.ELK) and according to a control law.

A system for testing line attenuation defects includes a data transmission line configured to transmit a forward signal in a first direction, at least one reflection point at a first location along the data transmission line, a test probe configured to (i) electrically contact a center conductor at a second location along the data transmission line, (ii) introduce a broadband data signal onto the data transmission line, and (iii) measure, at the second location, a return signal from the reflection point, and a spectrum capturing device in operable contact with the test probe. The spectrum capturing device is configured to (i) collect and arrange frequency data measured by the test probe for the test signal, the return signal, and a standing wave created by the sum of the broadband data signal and the return signal, (ii) determine the voltage VSWR of the standing wave, and (iii) calculate a line loss from the VSWR.

The disclosure is directed at a method and system for optical telecommunications performance monitoring via a dual frequency pilot tone. By applying a dual frequency pilot tone, with a first pilot tone frequency selected from a low frequency band and a second pilot tone frequency selected from a high frequency band, either simultaneously or alternatively, to a wavelength channel, one of the pilot tone frequencies may be adaptively selected to improve wavelength channel monitoring. More specifically, stimulated Raman scattering (SRS) caused crosstalk and chromatic dispersion (CD) caused pilot fading which adversely affect performance monitoring of the wavelength channel may be reduced.

An aspect of the disclosure provides methods and systems for encoding a data bit stream onto a pilot tone signal. Another aspect of the disclosure provides method and systems for pilot tone detection. In both, a coded pilot tone signal is encoded using a code sequence m.sub.1 for each bit value of 1 (b.sub.1) and a code sequence m.sub.0 for each bit value of 0 (b.sub.0) of a data bit stream including pilot tone data bit values of 1 (b.sub.1) and bit values of 0 (b.sub.0), with each code sequence having multiple coding bits in the duration of each bit. Pilot tone detection can further include decoding each code sequence of the coded pilot tone signal using a plurality of successive overlapping measurement windows. In some embodiments each measurement window is of the same duration, being of the duration of each code sequence, and detecting each code sequence comprises selecting one of the plurality of measurement windows to represent a complete code sequence.

A communication device includes: an optical-communication circuit that is capable of performing optical communication with a different communication device and transmits a first electric signal to the different communication device at a startup time of the communication device; an electro-communication circuit that is capable of performing electro communication with the different communication device and receives a second electric signal transmitted from the different communication device in response to the first electric signal; and a control circuit that transmits error information indicating an error in the optical communication to a device after the second electric signal is received by the electro-communication circuit.

A communication device includes: an optical-communication circuit that is capable of performing optical communication with a different communication device and transmits a first electric signal to the different communication device at a startup time of the communication device; an electro-communication circuit that is capable of performing electro communication with the different communication device and receives a second electric signal transmitted from the different communication device in response to the first electric signal; and a control circuit that transmits error information indicating an error in the optical communication to a device after the second electric signal is received by the electro-communication circuit.

An apparatus includes: a laser driver configured to output a laser diode current in accordance with a transmit data, a bias control code, and a modulation control code, a laser diode configured to receive the laser diode current and output a light signal, a photodiode configured to receive the light signal and output a photodiode current, a reference driver configured to output a reference current in accordance with the transmit data, the transmit enable signal, a reference bias code, and a reference modulation code, a two-fold comparison circuit configured to compare the photodiode current and the reference current and output a first decision and a second decision, and a DSP configured to adjust the bias control code and the modulation control code in accordance with the first decision and a second decision. A method provides reliable light output using the described apparatus.

An example system includes a transceiver and a microcontroller. The microcontroller is configured to receive, from first and second network interfaces of the transceiver, a plurality of messages from a hub node and the leaf nodes. Each of the messages corresponds to a respective one of the ingress or egress data flows. The microcontroller is also configured generate a resource assignment map based on the messages. The resource assignment map includes pairings between a respective one of the ingress data flows and a respective one of the egress data flows, and, for each of the pairings, an indication of a respective network resource assigned to exchange the egress data flow of that pairing with a respective one of the leaf nodes. The microcontroller is also configured to generate a command to cause the transceiver to transmit the egress data flows in accordance with the resource assignment map.

Disclosed are methods for monitoring and measuring Optical Signal-To-Noise Ratios in optical communications systems. One exemplary method involves intentionally inserting zero power symbols into an optical signal stream such that those periods of time in which only zero power symbols are transmitted may be detected and compared with periods of time in which signals modulated with information including both signal and noise are detected such that the OSNR may be determined.

A system and method including polarization modulation of supervisory signals for reducing interference with data signals in a wavelength division multiplexed optical communication system. At least one supervisory signal for monitoring a transmission path and/or elements coupled to the transmission path is fast polarization modulated and launched with data signals onto the path. Polarization modulating of the supervisory signal reduces impact of the supervisory signal on the data signals and improves system performance.