Abstract: Disclosed is a technique for compensating for optical passband shift of an optical component (for example an optical demultiplexer). A broadband source coupled to a dispersive element generates a chirped pulsed optical signal. Data is modulated onto particular wavelengths of the chirped pulsed optical signal by appropriately synchronizing a data modulator. The modulated signal is transmitted to the downstream optical demultiplexer, which may be subject to passband shift due to, for example, changes in environmental conditions. A feedback signal from an output port of the demultiplexer is provided to the transmitter and is used to phase shift the modulator. The phase shift results in effectively adjusting the wavelength onto which the data is modulated to substantially correspond to the passband centers of the demultiplexer.

Abstract: A method and apparatus for controlling bias and alignment in an optical signal transmitter for providing intensity modulation and DPSK modulation to an optical signal, e.g. in an RZ-DPSK modulation format. Output power in dither signals applied to the bias signals may be detected by a low speed photodetector. One or more of the bias signals may be adjusted in a low speed control loop in response to an error signal obtained by mixing the detected signal with the low frequency dither signals.

Abstract: The present photonic RF generation and distribution system provides a system and method for distributing an RF output signal. The photonic RF distribution system includes two optical sources for generating optical signals. A first optical source (42) is operable to generate a first optical signal having an operating frequency. A second optical source (44) is operable to generate a second optical signal having an operating frequency. A modulator (46) is operable to impress an RF modulation signal on a tapped portion of the first optical signal such that a modulated signal is generated. A first coupler (52) combines the modulated signal with a tapped portion of the second optical signal, thereby forming a combined signal having a difference frequency component. A control photodetector (50) is responsive to the combined signal to generate a tone signal.

Abstract: The inventors propose herein a switch fabric architecture that allows broadcasting and fast channel access in the ns-range. In various embodiments of the present invention, 10 Gb/s receiver modules are based on a novel heterodyne receiver and detection technique, which is tolerant to moderate wavelength drifts of a local oscillator. A gain clipped electrical amplifier is used in the novel receiver as a rectifier for bandpass signal recovery.

Abstract: A method and apparatus to provide bandwidth control in a high speed line driver circuit is described.

Abstract: A wavelength stabilizing filter has a wavelength transmission characteristic curve that has its peak in a wavelength located between a first continuous set band and a second continuous set band longer in wavelength than the first set band, and that linearly drops from the peak toward the shorter wavelength side than the first set band and also toward the longer wavelength side longer than the second set band. A control unit generates a control signal needed to enable an optical tunable filter to extract signal light with a predetermined wavelength from an inputted WDM signal, based on light transmitted through the wavelength stabilizing filter.

Abstract: The discrimination phase margin monitor circuit (10) of the present invention comprises a first discrimination circuit (11 and 12) discriminating an input data signal using a clock signal extracted from the input data signal, a second discrimination circuit (13 and 14) discriminating the input data signal using a clock signal with a frequency different from that of the clock and an operation circuit (15 and 16) calculating the exclusive OR of the output signal of the first discrimination circuit and that of the second discrimination circuit and obtaining a phase margin monitor output signal by averaging the exclusive ORs.

Abstract: Apparatus and methods for linearizing an optical transmitter are described. A linearized optical transmitter according to the present invention includes a modulator bias voltage supply that biases an optical modulator. The optical modulator modulates an optical signal with a payload modulation signal. A feedback circuit receives electrical distortion signals generated by the modulator and generates a control signal in response to at least one of the electrical distortion signals. The control signal changes the bias voltage generated by the modulator bias voltage supply so as to reduce the at least one electrical distortion signal.

Abstract: An optical signal transmission apparatus for transmitting a plurality of data signals comprising a plurality of inputs for receiving a respective one of the data signals and delivering the respective data signal with a controlled phase and at a controlled data rate. A plurality of optical carrier signals having different wavelength is generated. Each of a plurality of first modulators is operative for modulating a respective one of the optical carriers with a respective data signal to provide a first-modulated optical carrier signal. An optical signal-routing device has a plurality of input ports, each port being for receiving a respective one of the first-modulated optical carrier signals and delivering it to the output port of the device.

Abstract: Optical impairments such as dispersion and fibre nonlinearity are compensated by generating a pre-distorted electrical signal at the transmitter. This signal is modulated onto a carrier signal, so that it is upconverted in frequency. This up converted signal is then used to modulate an optical source. Generally the optical signal will have two sidebands, one of which has the correctly pre-distorted information and the other which is unwanted. Information in the unwanted optical sideband is either filtered optically or electrically. In the preferred embodiments, the transmitter uses a tunable semiconductor laser with an integrated electroabsorption modulator to modulate the light. The preferred receiver is a coherent receiver with a tunable local oscillator laser. The receiver uses an electrical filter to remove the information in the unwanted sideband.

Abstract: An optical RZ transmitter comprises an optical signal source and a pair of electro-optical modulators in tandem, one arranged to receive a NRZ electrical data signal and the other a clock signal at the data rate of the data signal. The phase difference between the data signal and the clock signal is controlled by adding a first dither signal to a bias signal applied to the modulator receiving the data signal, and a second dither signal, having a different frequency, to the phase difference. The amplitude of variations in the power of the optical output signal corresponding to cross-modulation of the first and second dither signals is detected and the phase difference is controlled in response to the detected amplitude.

Abstract: In the invention, an input light including a signal light and a noise light within a signal wavelength band of the signal light is divided into a first component with a polarization parallel to a polarization direction of the signal light and a second component with a polarization orthogonal to the polarization direction of the first component. The first component is supplied into a first arm and the second component into a second arm. The optical phase of the second component in the second arm is shifted so that the optical phase of the second component in the second arm relatively differs by ? from the optical phase of the first component in the first arm. The first component output from the first arm and the second component output from the second arm are combined to make the noise lights included in the first and second components interfere with each other.

Abstract: Methods and apparatus for the active control of a wavelength-swept light source used to interrogate optical elements having characteristic wavelengths distributed across a wavelength range are provided.

Abstract: The multi-channel optical transmitter is composed of a tunable optical signal source, an optical multiplexer and an intensity reducer. The tunable optical signal source includes a tunable laser, and additionally includes an optical signal output through which it outputs an optical signal to one of the inputs of the optical multiplexer. The intensity reducer is for reducing the intensity of the optical signal output by the optical signal source during tuning of the tunable laser. The intensity reducer prevents the tunable optical signal source from injecting high levels of noise into the channels during tuning of the tunable optical signal source.

Abstract: Using a switching signal from a coarse/fine switching and operation mode switching circuit, the width of change of a counter control value during power up is increased, and the width of change is reduced once a steady state is reached. In the steady state, the frequency of updating is limited by a control signal from an update permit control circuit. In the steady state, the frequency band of a current source in an LD driving circuit is reduced in width.

Abstract: The present invention relates to an apparatus and method for stabilizing a bias voltage for a pulse generating modulator, which can automatically detect an optimal bias voltage for an external modulator, which is used in RZ or CSRZ modulation of an optical transmission signal using NRZ data to generate a reference pulse optical signal, and maintain the optimal bias voltage. In the bias voltage stabilizing method of the present invention, an output signal of the external modulator, to which the bias voltage to be stabilized is applied, is detected, a drive clock signal applied to the external modulator is detected, a mean output value of the products obtained by the multiplication of the output signal and the clock signal is periodically examined, and the bias voltage is adjusted so that the mean output value becomes “0”.

Abstract: One embodiment of the invention relates to producing optical pulses for use on a transmission link. A light source is configured to produce an optical signal. A pulse generator is coupled to the light source. The pulse generator is configured to receive, for a first channel, the optical signal and a clock signal. The pulse generator is also configured to modify the optical signal based on the clock signal to produce an optical pulse having a predetermined pulse shape. The clock signal is associated with the predetermined pulse shape.

Abstract: An apparatus for accelerating assessment of an optical transmission system using Bit Error Rate (BER) tests calculates Q-factors for at least two different extinction ratios from measured test BER values, and extrapolates to determine a Q-factor for an operational extinction ratio, whereby the operational BER value for the operational extinction ratio can be calculated.

Abstract: An optical transmitter comprises an amplitude modulation unit performing amplitude modulation of only a one-side amplitude of a main signal with a low-frequency signal having a predetermined frequency. An optical modulator receives an input signal generated after the one-side amplitude modulation, and modulates an incoming light in response to the received signal in accordance with a predetermined modulation-characteristic curve to output an optical output signal. An operating point control unit applies a predetermined bias voltage to the optical modulator to control a level of the input signal substantially applied to the modulation-characteristic curve so that the one-side amplitude of the main signal is applied to a minimum portion of the modulation-characteristic curve of the optical modulator.

Abstract: An optical receiver includes a first light receiving element to convert an optical signal to an electric signal and to output the electric signal from one end. A light receiving element row is connected to the other end of the first light receiving element to supply electric power to the first light receiving element. The light receiving element row includes a plurality of second light receiving elements connected in series.

Abstract: A first peak hold circuit holds a peak potential of a positive phase voltage signal output from a differential output amplifier, and a second peak hold circuit holds a peak potential of a negative phase voltage signal output from the differential output amplifier. An adding circuit adds an output signal of the first peak hold circuit and an output signal of the second peak hold circuit. A differential input amplifier amplifies and outputs a voltage difference between a reference voltage and an addition result voltage signal of the adding circuit. A current output circuit outputs a DC current based on an output voltage of the differential input amplifier. A current switch circuit converts a DC current to a pulse current so as to supply the pulse current to a laser diode.

Abstract: A cosite interference rejection system allows cancellation of large interfering signals with an optical cancellation subsystem. The rejection system includes an interference subsystem coupled to a transmit system, where the interference subsystem weights a sampled transmit signal based on a feedback signal such that the weighted signal is out of phase with the sampled transmit signal. The optical cancellation subsystem is coupled to the interference subsystem and a receive antenna. The optical cancellation subsystem converts an optical signal into a desired receive signal based on an interfering coupled signal and the weighted signal. The weighted signal is therefore used to drive the optical cancellation subsystem. The rejection system further includes a feedback loop for providing the feedback signal to the interference subsystem based on the desired receive signal.

Abstract: An optical transmitter device capable of high-speed shutdown of optical output. A bias controller generates a low-frequency signal, extracts the frequency component of a low-frequency signal from an electrical signal fed back thereto, and compares the phase of the frequency component of the low-frequency signal generated thereby with that of the frequency component of the extracted low-frequency signal, to generate a direct-current voltage with which the operating point of an optical modulator is optimized. Using a half-wave voltage of the optical modulator and an optimum voltage, a bottom voltage calculation unit calculates a bottom voltage corresponding to a minimum of the operation characteristic curve of the modulator. A voltage selection unit selects the direct-current voltage during normal operation, to apply the optical modulator with a bias voltage derived from the direct-current voltage, and selects the bottom voltage at the time of shutdown, to apply the bottom voltage to the modulator.

Abstract: An optical transceiver includes a single integrated circuit chip to integrate the drive, receive, control, and monitoring functions of the optical transceiver. The single chip may further have an advance replacement algorithm and monitoring algorithm for the opto-electronic devices of the optical transmitter and receiver to generate flags and/or an advance replacement indication. Methods, apparatus, and systems are disclosed.

Abstract: Method and apparatus for synchronizing two different types of modulators in an optical transmission system includes a first modulator generating an optical pulse train, a second modulator encoding data onto the optical pulse train, an optical filter resolving upper and lower modulation sidebands of the optical data and an analyzer measuring the optical power of modulation sidebands and converting the received optical power of the sidebands into a control signal for synchronizing the two modulators. A wedged etalon is the filter element selecting the USB and LSB from the optical data spectrum. The analyzer contains photo-detectors measuring the optical power of the filtered USB and LSB and an electronic differential amplifier producing a control signal based upon photo-detector output. The phase shifter, in response to the control signal, adapts the temporal delay of the first modulator to reduce differences between the power levels of the upper and lower sidebands.

Abstract: The optical transmitter has a feature that the transmitter comprises a light-emitting device, an optical splitter, a dispersion controller including a first dispersion generator and a waveform monitor, and a processing unit. The optical splitter splits light emitted from the light-emitting device, and guides one of split light into the first dispersion generator. The first dispersion generator adds dispersion, an amount of which is predefined by the processing unit so as to reflect dispersion of the optical path to the receiving station, to the split light and outputs dispersed light to the waveform monitor. The processing unit maintains the dispersed light output from the dispersion generator to have a predetermined quality.

Abstract: An optical transmission controller for controlling an optical transmission system is presented. The optical transmission controller according to the present invention includes a laser controller, a modulator block controller, and a modulation driver controller. In some embodiments, the optical transmission controller is formed on a single integrated circuit chip. In some embodiments, the optical transmission controller includes a digital signal processor or microprocessor executing instructions for providing signals to a laser module, a modulator block and modulation drivers.

Abstract: The invention describes methods and systems for monitoring the performance of an optical network by marking a group of optical signals with a set of identification tags which are unique to network characteristics. In the preferred embodiments, fiber identification (FID) and bundle identification (BID) tags are encoded into optical signals by marking an optical signal with low frequency dither tones whose frequencies are unique to the fiber section and to a bundle of fibers respectively. Detecting of the FID and BID tones provides more effective and accurate monitoring of performance of the optical network and allows determining of the network topology, e.g. paths of optical channels and traffic load through different fiber sections in the network. Other sets of hierarchically arranged identifiers encoded into optical signals have also been proposed, including band, conduit, city, region, country, etc. identifiers, as well as identifiers related to network security and service characteristics.

Abstract: A self-adjusting data transmitter driver can be used for transmission of analog or digital data signal over any suitable communication channel, such as, for example, optical, electrical, wireless and satellite. The optical transmitter driver may be used to drive a single laser as well as an array of lasers. An optical transmitter driver including a laser diode driver can be used to provide modulation and bias currents to drive a laser diode in an optical communication system. A high speed photodiode is used to monitor high frequency characteristics of the optical data signal while one or more photodiodes are used to detect source parameters of the optical data signal. To compute the feedback parameters, parameters including BER, data-eye, discrete optical data integrity parameters and discrete optical parameters are determined using the feedback detectors. The feedback parameters are used to adjust the optical quality of the laser output towards optimization.

Abstract: A radio-frequency-signal generator generates an RF signal. An optical monitor monitors a first intensity of a reference signal and a second intensity of a drop signal. A reference-frequency determining unit determines, based on the first intensity, a first frequency of an RF signal that causes the AOTF to output the reference signal. A temperature detecting unit detects a temperature of the AOTF. A frequency calculating unit calculates a second frequency of an RF signal that causes the AOTF to output a drop signal of a desired wavelength. A control unit controls the RF-signal generator to generate the RF signal of the second frequency calculated.

Abstract: This invention provides a technique for realizing low-cost optical signal waveform monitoring with improved realtimeness to be applied to signal quality monitoring in an actual optical transmission system, and a technique for stably controlling an optical transmitter/receiver and various compensators by means of this waveform monitoring. Opening/closing of a optical gate is controlled by means of a clock signal synchronized with an optical signal input from a photocoupler and having a period equal to the bit interval of data or N (N: a positive integer) times longer than the bit interval to allow each pulse of the optical signal for one bit of data to pass through the optical gate for only part of the time width of the gate. A photoelectric conversion element to which the optical signal transmitted through the optical gate for only part of the time width obtains an average light intensity of the input optical signal. Information on this average light intensity is output to a monitoring output section.

Abstract: Systems and methods for regulating optical power are described. A system for regulating optical power includes a laser driver circuit that receives an enable/disable signal and a data modulator input. The enable/disable signal regulates asynchronous mode operation. The system also includes a laser module including a laser diode emitter and a photodiode detector. The laser module is coupled to the laser driver circuit and receives a laser bias current from the laser driver circuit. The system also includes a switch coupled to the photodiode to receive a signal from the photodiode detector. The system also includes an automatic power control (APC) feedback circuit that receives a signal from the switch and provides a laser bias current feedback signal to the laser driver circuit to compensate for power output changes in the laser diode emitter over time.

Abstract: An optical transmission controller includes a semiconductor-laser, a semiconductor laser driver, a monitor photoreceptor, a waveform detector and a phase relation adjuster. The semiconductor laser driver allows the semiconductor laser to output an optical signal. The monitor photoreceptor monitors the optical signal output. The waveform detector detects a fall state of the optical signal output. The phase relation adjuster adjusts a phase relation between a fall timing of an input current and a variation timing of a relaxation oscillation of the optical signal output in accordance with a detection result of the waveform detector.

Abstract: An optical transmitter photonic integrated circuit (TxPIC) comprises a semiconductor monolithic chip with a plurality of optical signal channels where each channel comprises a modulated signal source. The output from the modulated signal sources are coupled to an input of an integrated optical combiner to form a WDM output signal for transmission off the TxPIC chip to an optical transmission link. An optical service channel (OSC) is also integrated on the TxPIC chip to receive a service signal from the optical receiver source which is also coupled the optical transmission link.

Abstract: The optoelectronic transceiver includes first and second controller ICs. Each controller IC includes logic, a memory, an interface, and at least one input port. Each memory is configured to store digital diagnostic data and has a unique serial device address to allow a host access to each of these controller ICs separately and independently. At least some of the digital diagnostic data is common to both the first controller IC and the second controller IC. The inclusion of two controller ICs allows the same diagnostic data to be stored in completely different memory mapped locations. This allows hosts that are preconfigured differently to read different memory mapped locations on the different controller ICs to obtain the same diagnostic data.

Abstract: A system and method for improving the transmission quality of a WDM optical communications system begins by determining the bit-error rate for an optical channel before forward error correction is performed at a receiver. The pre-corrective bit-error rate is fed back through a feed back circuit that includes a parameter adjustment module which adjusts an optical signal parameter based on the bit-error rate. As examples, the signal parameter may be a channel power, dispersion, signal wavelength, the chirp or eye shape of an optical signal. The feedback circuit may also adjust various parameters within the WDM system, including amplifier gain, attenuation, and power for one or more channels in the system. By adjusting these parameters based on a pre-corrective bit-error rate, transmission quality is improved and costs are lowered through a reduction in hardware.

Abstract: A tunable dispersion compensator whose passband center wavelength changes when the amount of dispersion compensation is changed is suitably adjusted. The relationship between temperature for keeping the center wavelength constant and the amount of dispersion compensation is stored in advance. After controlling the amount of dispersion compensation to achieve best or optimum transmission quality, the amount of dispersion compensation is converted into temperature in accordance with the stored relationship and, based on that, the temperature is controlled to keep the center wavelength constant.

Abstract: Extremely advanced technology for scrambling an optical signal based on quantum mechanical fluctuation is used to provide a highly reliable optical communication method which can invalidate illicit activities such as wire-tapping, a system, and a laser oscillator which is used in the method and system. A transmitter side generates laser light, simultaneously oscillated at a plurality of wavelengths, the total number of generated photons being constant, and transmits a signal light comprising data which has been added to the light of the plurality of wavelengths; and at a receiving side, light, simultaneously oscillated at the plurality of wavelengths, is selected from the signal light, and the data is demodulated.

Abstract: A system for matching a optical filter characteristic of a first filter tunable in wavelength with an optical first signal comprises a modulator for modulating at least a part of the first signal with a modulation signal before being applied to the first filter. An analyzing unit derives a control signal for tuning the first filter by analyzing the modulated first signal after passing the first filter in conjunction with the modulation signal.

Abstract: A phase modulation circuit for outputting a modulated signal of an input signal which has been modulated to a desired phase. The circuit includes a light emitting element for emitting light according to an input signal and outputting a modulated signal, a bias current source for supplying in advance to a light emitting element a bias current smaller than the light emitting threshold current of the light emitting element, a bias current control unit for controlling the bias current according to a desired phase for supplying to the light emitting element a modulation current for causing the light emitting element to emit light according to the input signal, and a modulation current control unit for controlling the modulation current according to the phase shift resolution in the phase modulation circuit. The modulation current control unit controls modulation current further according to the phase range in the phase modulation circuit.

Abstract: The influences on transmission quality caused by chirp and self-phase modulation are at least largely corrected by way of an optimally set operating point of the modulator (2). Suitable criteria are obtained in control loops in order to maintain the optimal setting.

Abstract: A high-speed optical transmitter having an optical modulator and a driver circuit while maintaining optical modulator performance. The high-speed optical transmitter comprises the optical modulator which modulates and outputs an input light in accordance with an applied voltage, and a driver circuit which outputs the applied voltage into the optical modulator and has an emitter follower circuit at an output stage thereof.

Abstract: An optical multiplex communication system includes a transmission part and a receiving part, wherein the transmission part includes a transmission quality detecting part which measures and transmits a transmission quality information for the channels based on a request from the transmission part; the receiving part includes a variable optical attenuation part controls the optical signal level for the channels, an optical level setting part controls the variable optical attenuation part based on a setting value, a setting control part adding the setting value to the optical level setting part based on a request for setting.

Abstract: An improved analog optical system which provides improved dynamic range as well as sensitivity relative to known analog optical systems. The analog optical system includes a Mach-Zehnder modulator (MZM) operated with a low bias to improve sensitivity. In accordance with an important aspect of the invention, the optical system utilizes two optical wavelengths with two effective bias points to cancel even ordered distortion associated with low biasing. Two lasers having different wavelengths are applied to the Mach-Zehnder modulator by way of a wavelength division multiplexer (WDM). Alternately, a single laser producing two optical carriers having different wavelengths could be used in place of the two single wavelength lasers and the WDM. The modulator bias control circuit forces two optical carriers to two bias points on opposite sides of the minimum bias point thus, providing equal modulation depth with opposite sign on each of the two optical carriers.

Abstract: Disclosed is a multi-wavelength locking method for a wavelength division multiplexing (WDM) optical communication network, and in particular, a multi-wavelength locking method and apparatus for a WDM optical communication system that can lock wavelengths of optical signals by producing pilot tones by applying a sine-wave current to a plurality of transmission lasers having different wavelengths, passing the optical signal through a Fabry-Perot etalon filter, and then Fourier-transforming the filtered optical signal.

Abstract: Systems, apparatuses, and methods for driving an optical source with a current source. The optical source driver has a primary control loop having a DC—DC converter and an operational amplifier, wherein the DC—DC converter has a power input, a power output connected to the input of the optical source, and a control input, and wherein the operational amplifier has a first input connected between the optical source and the current source, a second input, and an output connected to the control input of the DC—DC converter, for controlling the output of the DC—DC converter in response to a control signal at the second input.

Abstract: A detector outputs a detection signal indicating amplitude variation of an input frequency-multiplexed signal. An amplitude controller adjusts the amplitude of the frequency-multiplexed signal by referring to the detection signal. A modulator modulates the amplitude-adjusted frequency-multiplexed signal to produce a predetermined modulated signal. A second multiplexer multiplexes the modulated signal and the detection signal to produce a multiplexed signal. An optical transmitter converts the multiplexed signal into an optical signal, and then sends it out to an optical transmission path. An optical receiver converts the received optical signal into an electrical signal. A separator separates the modulated and detection signals from the electrical signal. A demodulator demodulates the modulated signal to output the frequency-multiplexed signal. An amplitude adjuster adjusts the amplitude of the frequency-multiplexed signal by referring to the detection signal to reproduce the original amplitude variation.

Abstract: Extremely advanced technology for scrambling an optical signal based on quantum mechanical fluctuation is used to provide a highly reliable optical communication method which can invalidate illicit activities such as wire-tapping, a system, and a laser oscillator which is used in the method and system. A transmitter side generates laser light, simultaneously oscillated at a plurality of wavelengths, the total number of generated photons being constant, and transmits a signal light comprising data which has been added to the light of the plurality of wavelengths; and at a receiving side, light, simultaneously oscillated at the plurality of wavelengths, is selected from the signal light, and the data is demodulated.

Abstract: A method and system for dispersion control of electromagnetic signals in communication networks by narrowing the widths of electromagnetic pulses such as modulated laser signals. Generally, in the preferred embodiment, the present invention utilizes a feedback loop based on dither frequency modulation which dynamically adjusts the alignment of the laser center frequency with the filter passband. In this way, there is an acceptable tradeoff between optical power and pulse width, so a higher power laser can be used to generate a narrower optical pulse. The narrower pulses then travel farther in the fiber link before reaching their dispersion limit. It is believed that, by using this invention, existing link distance could be doubled, while re-using existing installed singlemode fiber. The systems employing the feedback loop may be information carrying or control systems.

Abstract: A WDM transmitter comprising an array of M pump lasers multiplexed by an M×N multiplexer, in the form of a coupler, and used to feed an array of N optically pumped fiber lasers emitting at wavelengths ?1, ?2, . . . ?N. The parameter M determines the number of pump lasers as well as the number of inputs of the pump-multiplexing coupler and can be smaller or equal to parameter N that determines the number of optically pumped lasers. The fiber laser outputs are passed through N isolators before entering N modulators were the signals are monolithically modulated. The outputs of the modulators are passed through an array of N tunable attenuators. Finally all the individual channel outputs are recombined into a single output in a combiner. The output will typically lead to an optical network. The proposed architecture may also be used for optical amplifiers, especially fiber-based optical amplifiers.