Abstract: An optical packet network system of a ring type, capable of preventing degradation of an optical signal, can be implemented by providing a mechanism relatively simple in structure, capable of erasing light noise if the optical packet signal does not exists. In the optical packet network system made up by interconnecting respective nodes adjacent to each other, and connecting a sending source of an optical packet signal to a ring, a light noise removal function block is provided between the respective nodes adjacent to each other.

Abstract: An optical repeater device of the present invention comprises: a preamble compensating circuit 53, for taking out a normal data signal from burst signals propagating through a communication transmission path, and for adding a preamble signal before and/or after the data signal. Furthermore, the preamble compensating circuit 53 comprises: a detector circuit 53a, for inputting the burst signal, and for outputting only the normal data signal; a buffer circuit 53b, for storing the data signal output from the detector circuit 53a, and for outputting thereof; a preamble signal generation circuit 53d, for outputting at least one type of the preamble signal; and an data output select circuit 53e, for outputting the data signal at the time of the data signal input from the buffer circuit 53b, and for outputting the preamble signal from the preamble signal generation circuit 53d at any other time thereof.

Abstract: In an optical fiber communication system, the input power to an all-optical nonlinear device in an optical regenerator is monitored and adjusted such that the regenerator operates at an optimized operation point.

Abstract: An optical signal processing device includes a waveform width widening unit configured to widen a waveform width of an optical signal; and an optical limiter circuit, to which the optical signal the waveform width of which is widened is input, configured to suppress an intensity of the optical signal in a region where an input intensity and an output intensity are not proportional.

Abstract: The present invention provides a single fiber bidirectional optical transmission system capable of realizing the extension of a single fiber bidirectional long distance at a moderate price. An optical signal outputted from a second optical transmitter is incident on an optical amplifying portion passing through an optical circulator, a single fiber bidirectional transmission path, an optical circulator and an optical Blue/Red filter. The optical signal outputted from a first optical transmitter is incident on the optical amplifying portion passing through a dispersion compensator and the optical Blue/Red filter.

Abstract: An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing the parameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: An optical add-drop function part of an optical add-drop multiplexer has an output end of transmitted light signal in which an optical termination mechanism formed by an optical detector for detecting open of an optical fiber, an optical switch, and an optical terminator are mounted. Further, a reflection level calculation circuit, a reflection warning determination circuit, and an optical switch selection circuit are mounted to perform laser safety in the optical add-drop function part as well. The laser safety part in the optical add-drop function part is operated earlier than the laser safety part in an optical amplification function part.

Abstract: The relative launch power of signals at an add/drop node transponder is controlled to maximize available power. Known values of signal bandwidth and likely noise in the signal path, for example, derived from the system manager, are used to control the launch power into the optical amplifier, in order to optimize the launch power accordingly.

Abstract: A repeater is disclosed that transmits an optical signal using wave division multiplexing. The repeater includes a demultiplexing unit that separates plural channels contained in the optical signal, an adjusting unit that adjusts at least optical power of each of the channels according to a control signal, a multiplexing unit that outputs a multiple wavelength signal in which the channels are multiplexed, and a monitoring unit that determines a modulation scheme and a bit rate of the optical signal for each of the channels so as to generate the control signal.

Abstract: A wavelength division multiplexed optical signal transmission method, a wavelength division multiplexed optical signal transmission system and an optical repeater enabling the number of wavelengths to be detected without error even when optical noise is caused in the optical repeater and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal to be performed properly. An optical repeater processes controlled optical signals of different wavelengths individually based on a control optical signal that contains wavelength number information indicating the total number of wavelengths and the presence or absence of a controlled optical signal with respect to each wavelength. Thus, even when optical noise is caused in the optical repeater, the number of wavelengths can be detected without error and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal can be performed properly.

Abstract: In a wavelength-division-multiplexing optical transmission system in which optical-node apparatuses that perform relay transmission of wavelength-division-multiplexed light are located at specified nodes in a main optical transmission path, an optical amplifier switches level control to constant-gain control when there is a notification of a change in the number of multiplexed wavelengths, and then after a specified amount of time restarts level control so that the level becomes a target level that corresponds to the actual number of wavelengths.

Abstract: An optical transmission system including an optical transmission path for transmitting WDM signals multiplexed different wavelength optical signals, the WDM signals including different bit rate optical signals or different modulation format optical signals; a repeater arranged in the optical transmission path, the repeater including a chromatic dispersion compensation unit for compensating chromatic dispersion compensation for the WDM signals; and a network management system including processes of determining a dispersion compensation ratio indicating the ratio with respect to the dispersion compensation amount at which the residual dispersion of the WDM signals are zero after transmission via the optical transmission path, on the bases of the mixture ratio of different optical signals included in the WDM signals, and variably setting the dispersion compensation amount for the in-line repeater according to the dispersion compensation ratio.

Abstract: A method of dynamically adjusting an optical module in an optical system including a plurality of transmission channels includes the following steps: measuring the quality of the optical signal at the output of the system as defined by an error function, varying an optical parameter of at least one module of the system, measuring a differential error introduced by each variation on the error function of the optical signal at the output of the system, estimating an operating point of the system corresponding to an expected reduction of the error function, and adjusting a parameter of an optical module toward the operating point of the system.

Abstract: The present invention provides a system and method for multiplexing DWDM channels on top existing CWDM infrastructure. An erbium-doped fiber amplifier amplifies DWDM signals in the DWDM domain to compensate for 10 G optics power budget limitations without blocking the CWDM signals. A passive WDM infrastructure allows the CWDM and DWDM signals to be multiplexed and de-multiplexed on the same fiber and allows seamless integration with existing infrastructure avoiding the need to sacrifice CWDM channels.

Abstract: In order to insert a regenerator into a wavelength cross-connect equipment, there is provided at least one port that demultiplexes one wavelength among the wavelength multiplexed signals that are input to a wavelength selective switch. An output of the port that demultiplexes one wavelength is input to the regenerator, and an output of the regenerator is again input to the WSS. The wavelength output from the regenerator is converted into another wavelength different from the wavelength that is input to the regenerator and can be processed by the WSS in advance. The output from the regenerator is input to the WSS through an optical coupler or another input port of the WSS.

Abstract: An optical repeater which includes a wavelength converter and a bit rate converter. The wavelength converter converts a wavelength of an optical signal from a first optical network to a wavelength of a second optical network. The bit rate converter converts a bit rate of the optical signal from the first optical network to a bit rate of the second optical network. The optical repeater transmits the optical signal from the first optical network to the second optical network at the converted bit rate and wavelength.

Abstract: An optical repeater device of the present invention comprises: a preamble compensating circuit 53, for taking out a normal data signal from burst signals propagating through a communication transmission path, and for adding a preamble signal before and/or after the data signal. Furthermore, the preamble compensating circuit 53 comprises: a detector circuit 53a, for inputting the burst signal, and for outputting only the normal data signal; a buffer circuit 53b, for storing the data signal output from the detector circuit 53a, and for outputting thereof; a preamble signal generation circuit 53d, for outputting at least one type of the preamble signal; and an data output select circuit 53e, for outputting the data signal at the time of the data signal input from the buffer circuit 53b, and for outputting the preamble signal from the preamble signal generation circuit 53d at any other time thereof.

Abstract: An all-optical processor and method for simultaneous 2R regeneration of the multiple wavelength-division-multiplexed (WDM) channels comprising: a nonlinear medium, wherein the nonlinear medium comprises one or more highly-nonlinear fiber (HNLF) sections adapted to receive multiple WDM channels from the input, and wherein further the HNLF sections are separated by one or more periodic-group delay devices (PGDDs). The all-optical processor may also include one or more amplifiers adapted to receive the multiple WDM channels; one or more de-interleavers adapted to separate the WDM channels into one or more sets of WDM channels, one or more optical band-pass filters to filter the channels received from the amplifier; one or more optical band-pass filters to filter the channels received from the non-linear medium; and one or more interleavers to receive the filtered channels from the periodic band-pass filter and to combine the sets of WDM channels into an output.

Abstract: In an optical transmission system which can keep a flat pass characteristic within an optical signal modulation band, a spectrum of a dropped optical signal within a modulation band per channel is monitored, and non-flatness for the optical signal is compensated by detecting the non-flatness of a pass characteristic of a transmission line from the spectrum.

Abstract: An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters.

Abstract: An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Abstract: The present invention provides systems and methods to convert a reconfigurable optical node multiple-input multiple-output (MIMO) system to a single-input single-output (SISO) system suitable for a proportional-integral-differential (PID) control process. Advantageously, the present invention allows PID control to apply to a MIMO optical node by modeling the node as two SISO systems. The present invention optimizes the division of gain and loss between components in the reconfigurable optical node. This provides means to control the net gain and loss of a series of components when the component chain being controlled includes those components that have a single action affecting multiple channels and components that affect only one channel. The present invention utilizes control of a single quantity of amplifier gain minus attenuation for each channel, and the coupling together of all channels in the amplifier which makes the channels inter-dependent.

Abstract: An optically amplified wavelength division multiplexing network has the functionality to add/drop channels at the optical add/drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.

Abstract: A system and method are disclosed for providing a transmission capacity on a data transmission path, wherein such data transmission capacity is provided with regard to a user on a transmission path by using at least one limiting unit.

Abstract: An optical receiver is disclosed comprising an erbium-doped fiber amplifier (EDFA) that is coupled to a photodiode and transimpedance amplifier without filtering output light signal in the EDFA. Optionally, a clock/data regenerator can be coupled to the electrical output of the transimpedance amplifier for compensating for noise distortion and timing jitter for affecting the control loop feeding back for adjusting the electrical current into a pump laser of an optical pre-amplifier. Furthermore, the optical receiver of the present invention can also be implemented in a transponder.

Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.

Abstract: An improved photonic switch having optical amplification is described. Signals are amplified before they are switched, after they are switched, or both before and after they are switched. The optical amplification compensates for fixed losses within the switch and transmission system, or provides output power equalization. The photonic switching system includes a demultiplexer for dividing incoming light into different wavelengths or wavebands. The different signals are then supplied to optical amplifiers. The amplifiers amplify the optical signals before supplying them to the optical switch core. Once in the optical switch core, the signals are switched as desired to specified output nodes, then multiplexed back together to provide an output signal from the photonic switching system. In some systems amplification is further provided on the output side.

Abstract: According to a WDM optical transmission system of the present invention, wavelength numbers information of a WDM signal light output from an upstream side optical amplifying unit to a transmission path fiber, and signal output level information thereof are transmitted to a downstream side optical amplifying unit utilizing a supervisory control light. In the downstream side optical amplifying unit, a loss (span loss) in the transmission path fiber is computed using the upstream side signal output level information and downstream side signal input level information, so that a gain to be set for a downstream side optical amplifier is calculated based on the computed loss, and also, the gain is corrected based on a difference between a target value of the signal output level computed using the wavelength numbers information and an actual measurement value thereof, so that the optical amplifier is controlled in accordance with the post-corrected gain.

Abstract: An optical wavelength multiplex transmission apparatus includes a demultiplexer (12) that divides a wavelength-multiplexed optical signal into optical signals of individual wavelengths, an optical attenuation control portion (13) that performs an optical attenuation control so that levels of the optical signals of individual wavelengths become constant, a multiplexer (16) that combines the optical signals of individual wavelengths after the optical attenuation control and multiplexes them, an optical signal level storing portion (15) that stores a first level range of optical signal levels, and an optical attenuation control stopping portion (22) that decides whether or not a level of each of the optical signals of individual wavelengths is within the first level range obtained from the optical signal level storing portion (15), and if its level is within the first level range, stops the optical attenuation control for an optical signal of a wavelength having the level.

Abstract: Gain setting of a receiving amplifier, is performed by detecting the necessity of gain setting when a receiving amplifier is turned on, requesting WDM transmission equipment in a preceding station to output ASE light; in a WDM transmission equipment of the preceding station, shutting off both passing-through light and added light, and outputting the ASE light corresponding to a predetermined number of wavelengths of signal light; in the receiving amplifier of the WDM transmission equipment in the station of interest, performing the gain setting by use of the ASE light; and on completion of the gain setting, the WDM transmission equipment of the station of interest, requesting the WDM transmission eouipment of the preceding station to halt the ASE light output, and the WDM transmission equipment of the preceding station, halting the ASE light output upon receiving the request and switching the output to an optical signal output.

Abstract: In the variable gain compensating apparatus, input power of optical amplifiers employed in respective optical repeaters is monitored, and the monitored input power is transferred to a down-stream side by using supervisor (SV) light. In a repeater equipped with a variable gain tilt compensator, input power monitor information of the optical amplifiers employed in the respective repeaters provided on the upper stream side is acquired from a supervisor signal. While utilizing a linear relationship established between a gain tilt of an optical amplifier and input power of the optical amplifier, the acquired input power monitor information is compared with a reference power value so as to calculate gain tilt amounts of the respective optical amplifiers. Then, the optimum gain tilt compensation amount of the variable gain tilt compensator is determined based upon the calculated gain tilt amounts.

Abstract: Disclosed is an apparatus for controlling wavelength-division-multiplexed light wherein overall power of wavelength-division-multiplexed light is rendered constant through control for uniformalizing the level of only one wave of maximum power, and wherein the levels of respective channels are made substantially uniform. Optical level control means controls the optical level of propagating wavelength-division-multiplexed light, and a portion of the wavelength-division-multiplexed light output from the output level control means is branched to a tunable optical filter, which selectively outputs the light of each wavelength contained in the wavelength-division-multiplexed light. The light of each wavelength output from the optical filter is photoelectrically converted to an electric signal by photoelectric conversion means.

Abstract: A digital optical network (DON) is a new approach to low-cost, more compact optical transmitter modules and optical receiver modules for deployment in optical transport networks (OTNs). One important aspect of a digital optical network is the incorporation in these modules of transmitter photonic integrated circuit (TxPIC) chips and receiver photonic integrated circuit (RxPIC) chips in lieu of discrete modulated sources and detector sources with discrete multiplexers or demultiplexers.

Abstract: A multichannel wavelength-division multiplex fiber optic transmission system includes an optical transmitter and an optical receiver connected by an optical line including at least one optical fiber and at least one set of channel regenerators. Successive regenerators regenerate respective groups of channels forming a subset of the set of channels.

Abstract: The present invention relates to a method and system for design and routing in telecommunications networks having transparent elements such as photonic switches. Transparent optical networks transmit signals optically, performing both switching and amplification photonically. As a result, transparent networks may be more economical than conventional “opaque” optical networks that convert signals to electronic form at each network node because they do not require as much equipment for performing optical-electrical conversion. However, transparent networks pose new operational challenges. Physical-layer impairments that are repaired by optical-electrical-optical (OEO) regeneration can accumulate along (transparent) connection paths. To effectively deploy and utilize transparency, mechanisms to assure that impairment-feasible paths exist and can be identified in the network are required.

Abstract: A terminal apparatus by which, even where BER data, for example, of an optical signal of an existing wavelength cannot be utilized, the optical output powers of the existing wavelength and an extension wavelength can be adjusted in a short period of time while eliminating quality degradation of the existing circuit. The terminal apparatus includes a level controlling section for controlling a total optical output power of an existing wavelength signal light and an extension wavelength signal light to a fixed level, a monitoring unit capable of monitoring the optical output power for each wavelength, and a controller for controlling the optical output power of the extension wavelength signal light so that the optical output power of the existing wavelength signal light monitored by the monitoring unit may not be lower than a minimum permissible optical output power.

Abstract: To demultiplex a low-speed optical pulse signal from a high-speed optical pulse signal, an optical clock generator generates an optical clock of a control wavelength ?p at a predetermined frequency out of a pulse signal light of a signal wavelength ?s. On one side of a saturable absorber, an optical band reflection mirror is disposed to reflect a light of the signal wavelength ?s and to transmit a light of the control wavelength ?p. A pulse signal light of the signal wavelength ?s reciprocates in the saturable absorber. An optical pulse of the pulse signal light of the signal wavelength ?s enters the saturable absorber almost simultaneously with different optical pulses of the optical clock on the ways of going and returning. The saturable absorber has a transmission factor relative to the signal wavelength ?s. The transmission factor varies as the saturable absorber absorbs a light of the control wavelength ?p.

Abstract: A multiplex optical communication system transmitting a multiplex optical signal between terminal equipments each including converters producing optical signals combined to the multiplex optical signal, through repeater equipment including an optical amplifier, under controlling the amplifier so that when a converter is added or removed, a time constant of the amplifier is equal to a time constant of the added or removed converter, or the amplifier produces output under constant output level control before adding or removing the converter and after the amplifier produces final output and constant gain control during the added or removed converter increases or decreases output. The time constant control is performed to the amplifier by making the amplifier repeat start and stop of increasing or decreasing output step by step in accordance with prescribed objective values corresponding to half way output of the optical amplifier.

Abstract: A wavelength division multiplexing system includes a wavelength division multiplexing transmission path including a multimode optical fiber that is codoped with germanium and fluorine. The wavelength division multiplexing system may further include a multiplexer and a demultiplexer, in which the multiplexer and the demultiplexer are coupled via the multimode optical fiber. The wavelength division multiplexing system may further include a first multiplexer/demultiplexer and a second multiplexer/demultiplexer, in which the first multiplexer/demultiplexer and the second multiplexer/demultiplexer are coupled via the multimode optical fiber so that a bidirectional wavelength division multiplexing is enabled.

Abstract: The present invention relates to a variable clamp equalization method and apparatus, the method includes measuring optical signal to noise ratio (OSNR) values for each wavelength, computing a raw power adjustment value for each wavelength, computing a raw power adjustment correction factor for each computed raw power adjustment value based on a computed OSNR range value in accordance with a pre-defined variable clamp value schedule, wherein a larger clamp is scheduled for use when the computed OSNR range value is larger, and a smaller clamp is scheduled for use when the computed OSNR range value is smaller. The method further includes determining a clamped power adjustment value for each wavelength, applying the corresponding determined clamped power adjustment value to each wavelength, and iterating the aforementioned until the computed OSNR range value is within pre-defined boundaries, whereby the signal is considered equalized.

Abstract: An optical communication system according to the invention comprises: a transmitting station 11; an optical transmission line 12 for transmitting an optical signal sent from the transmitting station 11; a receiving station 13 for receiving the optical signal outputted from the optical transmission line 12; a repeater station 14 provided at one point or more in the optical transmission line 12; and pump light sources 21 provided in at least two of the stations 11, 13, 14, for supplying pump light to the optical transmission line 12, wherein the pump light has two types or more of wavelength. It is possible to obtain a substantially flat gain as a function of wavelength in the whole optical communication system since the pump lights with different wavelengths are supplied from a plurality of points in the optical transmission line 12 and an optical signal is amplified with various Raman gain coefficients.

Abstract: A repeating apparatus and method using wireless optical transmission is disclosed. The repeating apparatus includes a donor device for transmitting two identical copies of an optical signal by receiving a RF signal from a base station and electro-optic converting the RF signal to an optical signal, and for transmitting a RF signal by receiving two identical copies of the optical signal and optic-electro converting the optical signal to a RF signal; and a coverage device for transmitting a RF signal to a mobile communication terminal by receiving two identical copies of the optical signal from the donor device and optic-electro converting the two identical copies of the optical signal to the RF signal, and transmitting two optical signals to the donor device by receiving the RF signal from the mobile communication terminal and elector-optic converting the RF signal to the optical signal.

Abstract: A method of controlling an optical wavelength division multiplexing transmission apparatus achieves stable wavelength division multiplexing optical transmission by switching a control mode of an optical amplification section in accordance with an input state of optical signals of various wavelengths. Accordingly, the method involves, upon startup of the optical wavelength division multiplexing transmission apparatus, initial setting of information such as the wavelengths being used and the number of wavelengths being used, setting the amount of optical attenuation for each wavelength to a maximum value, and setting an optical amplification unit to ALC.

Abstract: The invention is also related to devices for a synchronization of data in an optical WDM transmission system, consisting of the following parts: A wavelength demultiplexer (1) for demultiplexing the incoming data stream in the synchronizer, delay lines (2) for the individual wavelength channels, a multiplexer (10), a modulator (3) modulated by a high frequency clock signal (5) and at least one photodetector (4) tapped to output line (B) where the photodetector (4) is connected to an electronic control circuit (6) which is connected to the findividual delay lines (2) for an automatic delay control.

Abstract: The present invention provides a bilateral communication network system, particularly, a optical wireless communication system communicating information frames via an optical node mounted on a mobile object and a plurality of optical repeaters connected to a wired network, which can prevent transfer performance from deteriorating without increasing frames to be transferred. The optical wireless communication system is constituted as follows. A plurality of the optical repeaters having functions to switch information frames are attached to a ceiling. The optical node bilaterally communicating with the optical repeaters are mounted on a moving object such as a robot, a vehicle or the like. Information frames including address information of the optical node are periodically transmitted from an information processor connected to the optical node via optical wireless communication.

Abstract: A connection between a source node and a destination node is automatically routed and switched in a WDM photonic network, on receipt of a connection request. A switching and routing mechanism selects a plurality of valid link paths using a path tree, where invalid branches are eliminated based on constraints received in the connection request, and on a link and path cost functions. A regenerator placement tree is used for determining a plurality of viable regenerator paths for each valid link path. On the regenerator placement tree, non-viable branches are eliminated based on constraints received with the request and on regenerator availability at the intermediate nodes along the respective path, and on the specification of these available regenerators. Next, the switching and routing mechanism assigns a set of wavelengths to each viable regenerator path, and estimates the performance of the path using a Q estimator.

Abstract: The invention relates to a saturable light absorber adapted to receive different focused spectral components, wherein the structure of said saturable light absorber comprises microcavities integrated into a substrate and each associated with a respective one of said spectral components, each microcavity comprising a saturable absorber layer delimited by a top reflector and a bottom reflector and being disposed and having dimensions such that it receives only the focused spectral component associated with it.

Abstract: A digital signal channel bypass is provided as bypass around an optical network optical amplifier, in particular, an analog type optical amplifier, such as an EDFA, in an optical transport network or system. The digital signal bypass provides for an ability to maintain the existing optical amplifier OO amplification site while inserting a bypass that provides ultra low-cost OEO REGEN in a digital optical network (DON) utilizing both semiconductor electronic integrated circuit chips and semiconductor photonic integrated circuit (PIC) chips where all the optical components are in semiconductor integrated chip form providing 1R, 2R, 3R or 4R regeneration as well as other signal caring functionality. A salient feature of the digital signal bypass is to regenerate signals in the optical span that are outside the gain bandwidth of the EDFA or other such amplifier.

Abstract: The invention is aimed at providing a simple noise light elimination technique capable of eliminating noise light components contained in a signal light, together with wavelength components same as for the signal wavelength, with the condition of the light remaining as is, and an optical transmission system. To this end, an optical transmission system applied with a noise light elimination method according to the present invention comprises a high output type optical repeater and a noise light elimination unit for each required repeating span. This noise light elimination unit includes a dummy transmission path that, when a light of a power exceeding a threshold value is input, generates a return light due to stimulated Brillouin scattering (SBS). The signal light amplified in the optical repeater up to the power exceeding the threshold value is input to the dummy transmission path via an optical input/output section of the noise light elimination unit.