摘要:
Disclosed is a laser diode protecting circuit adapted to prevent a laser diode from producing an excessive emission when the laser diode is driven at low temperature, thereby assuring that the laser diode will not be damaged or degraded in terms of its characteristic. When the laser diode is started at low temperature, a laser diode protecting circuit has a power monitor circuit for monitoring backward power of the laser diode and a laser diode current limiting circuit for limiting the laser diode current when the backward power becomes equal to the set power. When the laser diode temperature subsequently rises and the backward power falls below the set power, an automatic current control circuit performs automatic current control in such a manner that the laser diode current attains a set current value. Alternatively, a temperature monitor circuit monitors the temperature of the laser diode and the laser diode current limiting circuit limits the laser diode current when the monitored temperature of the laser diode is less than the set temperature. When the laser diode temperature exceeds the set temperature, the automatic current control circuit performs automatic current control in such a manner that the laser diode attains the set current value.
摘要:
Disclosed is a laser diode protecting circuit adapted to prevent a laser diode from producing an excessive emission when the laser diode is driven at low temperature, thereby assuring that the laser diode will not be damaged or degraded in terms of its characteristic. When the laser diode is started at low temperature, a laser diode protecting circuit has a power monitor circuit for monitoring backward power of the laser diode and a laser diode current limiting circuit for limiting the laser diode current when the backward power becomes equal to the set power. When the laser diode temperature subsequently rises and the backward power falls below the set power, an automatic current control circuit performs automatic current control in such a manner that the laser diode current attains a set current value. Alternatively, a temperature monitor circuit monitors the temperature of the laser diode and the laser diode current limiting circuit limits the laser diode current when the monitored temperature of the laser diode is less than the set temperature. When the laser diode temperature exceeds the set temperature, the automatic current control circuit performs automatic current control in such a manner that the laser diode attains the set current value.
摘要:
The optical transmission apparatus for multiple wavelengths according to the present invention comprises; a light source, a temperature control section for controlling the temperature of the light source, a temperature control (ATC) loop for controlling the operation of the temperature control section, and a wavelength control (AFC) loop. The ATC loop detects the temperature of the light source and feedback controls the operation of the temperature control section, so that the optical output wavelengths of the light source fall within a wavelength capture range corresponding to a target wavelength of the AFC loop. The AFC loop has a wavelength detection filter having a periodic transmission wavelength characteristic. After the operation of the ATC loop has stabilized, a wavelength capture operation is commenced, and the operation of the temperature control section is controlled so that the optical output wavelength of the light source is captured at a stable point corresponding to a target wavelength, among a plurality of stable points.
摘要:
An optical transmitter comprises a first unit for generating an optical signal having a bandwidth given by a main signal, a second unit modulating the optical signal according to a control signal to extend the bandwidth of the optical signal, a third unit extracting backward light including SBS(stimulated Brillouin scattering) light generated in an optical fiber transmission line, and a fourth unit performing feedback control so that the power of the SBS light becomes substantially constant. Through the structure of the optical transmitter good transmission characteristics of a main signal are obtained and the suppression of the SBS is allowed.
摘要:
Disclosed herein is an optical transmitter suitable for stabilization of the output power and wavelength of an optical signal. The optical transmitter includes a light source for outputting a light beam, an external modulator for modulating the light beam according to a main signal to thereby output an optical signal, a power monitor for detecting the power of the optical signal output from the external modulator, and a control unit for controlling the light source so that the power detected by the power monitor becomes stable. The light source is controlled according to the power detected on the downstream side of the external modulator, so that the output power of the optical signal to be obtained can be maintained constant with high accuracy irrespective of variations in loss by the external modulator.
摘要:
A WDM optical transmission apparatus of the present invention comprises: a light source (1) for generating light whose wavelength is changed according to the temperature and a drive current; a temperature control section (4) for controlling the temperature of the light source so that a wavelength at the starting of emission of the light source is stabilized in an allowable range of optical output wavelength set in advance; a drive current control section (5) for controlling the drive current applied to the light source according to the allowable range of the optical output wavelength; a wavelength control section (3) for detecting a wavelength of light output from the light source and controlling the temperature of the light source based on the detection result, to lead the optical output wavelength into the vicinity of a predetermined target wavelength; and an operation control section (6) for controlling the start and stop of the control operation of each section at predetermined timing respectively corresponding to the time of optical output generation and the time of optical output stop.
摘要:
According to an aspect of an embodiment, a method of spectrum defragmentation in an optical network may include assigning an optical signal within an optical network to a first frequency slot that spans a first portion of an optical spectrum of the optical network. The method may also include constructing a frequency slot dependency map based on the assignation of the optical signal to the frequency slot. The method may also include reassigning, as a result of an optical signal departure event, the optical signal to a second frequency slot based on the frequency slot dependency map. The second frequency slot may span a second portion of the optical spectrum of the optical network.
摘要:
An optical network for reassigning a carrier wavelength of an optical signal may include first and second optical nodes. The first optical node may be configured to transmit an optical signal along an optical path. The first optical node may also be configured to tune a carrier wavelength of the optical signal from a first wavelength to a second wavelength, according to a continuous function, to reassign the carrier wavelength of the optical signal. The second optical node may be configured to receive the optical signal and may include a feedback loop configured to adjust a wavelength of a reference optical signal to approximate the carrier wavelength of the optical signal.
摘要:
A method may include constructing an auxiliary graph for a network comprising a plurality of network elements, the network elements having an Internet Protocol layer, a lower layer, and a wavelength layer, the auxiliary graph including a plurality of directed edges, the plurality of directed edges indicative of connectivity of components of the plurality of network elements. The method may further include: (i) deleting directed edges from the auxiliary graph whose available bandwidth is lower than the required bandwidth of a selected demand; (ii) finding a path for the demand on the auxiliary graph via remaining directed edges; (iii) deleting at least one directed edge of the auxiliary graph on the wavelength layer along the path; (iv) adding lower layer lightpath edges to the auxiliary graph for a lower layer lightpath for the path; and (v) converting lower layer lightpaths to Internet Protocol lightpaths if a conversion condition is satisfied.
摘要:
A residual chromatic dispersion target value at a terminal node is set for each wavelength path, and also, candidates of a dispersion compensation amount settable in each chromatic dispersion compensation module on an optical network are set, and further, computation processing is executed for selecting the dispersion compensation amount in each chromatic dispersion compensation module from the candidates so that the sum of errors between the residual chromatic dispersion amounts and the set residual chromatic dispersion target values at the terminal nodes for all of wavelength paths becomes minimum. As a result, for each wavelength path on the optical network, the dispersion compensation amount in each chromatic dispersion compensation module can be designed in optimum so as to satisfy the desired optical signal quality at the terminal node, while considering the residual chromatic dispersion during the transmission.