Abstract: A phase-modulated analog optical link that uses parallel interferometric demodulation to mitigate the dominant intermodulation distortion present in the link. A receiver for demodulating phase modulated optical signals includes a splitter dividing the phase modulated signal into parallel optical paths, each optical path having an asymmetrical interferometer, the time delays of the interferometers being unequal, and each optical path includes a photodiode optically connected to an output of the interferometer. Outputs of the photodiodes enter a hybrid coupler. Alternatively, outputs of the interferometer enter a balanced photodetector. A phase shifter or time delay element can be included in one optical path to ensure inputs to the coupler or balanced photodetector have the correct phase. The input power to the parallel optical paths is split in a ratio that balances the third-order distortion in the output photocurrent.

Abstract: An optical receiver comprises branching units for branching and supplying the signal lights to be inputted to the first to fourth optical waveguides provided on a substrate, second to third optical waveguides for giving delay time differences corresponding to a symbol of the DMPSK modulated signal, a demodulating unit for demodulating two light signals through interference of signal lights between the first to second optical waveguides and between the third to fourth optical waveguides, two optical detectors for converting two light signals from the demodulating unit, and a light path length varying unit for identically varying each light path length of two optical waveguides being arranged through selection of combinations of the first and third optical waveguides, the first and fourth optical waveguides, and the second and third optical waveguides in one region when the wavelength of the signal light is varied.

Abstract: In an optical receiving apparatus for receiving an optical DQPSK signal, a phase difference between both arms of an optical interferometer is controlled to an optimum value. The optical DQPSK signal is incident on two optical interferometers in each which a delay-time difference between two arms is set to be equal to a 1-symbol time of the optical DQPSK signal and which are orthogonal to each other. The optical receiving apparatus converts the optical DQPSK signal into an intensity signal and receives it. A differential amplifier obtains a difference signal between outputs of a pre-amplifier and a discriminator connected thereto. The difference signal includes, as an amplitude, a phase shift in a phase section. A control circuit adjusts the phase of the phase section in the optical interferometers to reduce this difference signal, and changes the phase difference between the two arms to a desired phase difference.

Abstract: A method and apparatus for estimating fiber dispersion in an optical communication system including transmitting an optical signal carrying a unique word along an optical communication path, receiving the optical signal carrying the unique word from the optical communication path, producing an electrical signal corresponding to the received unique word, and processing the electrical signal corresponding to the received unique word to produce an estimate of the fiber dispersion in the optical communication system.

Abstract: In a cryptographic key distribution system by the phase modulation using a single photon state or a faint LD light, there is required an interferometer independent on polarization and stabilized against thermal fluctuations in order to make a transmission distance longer. Cryptographic key distribution systems are generally low in cryptographic-key-generating efficiency, and an improvement in the efficiency is demanded. In the present invention, two interferometers are disposed within the receiver so as to require no phase modulator within the receiver, thereby achieving a polarization-independent receiver. The pulses are paired, and the signal is transmitted with the relative phase, and the interval of the paired pulses is sufficiently reduced to set the optical path within the interferometer in the receiver to be smaller, thereby achieving the interferometer stabilized against thermal fluctuations.

Abstract: A communication terminal apparatus receives a management signal at a bit rate A and a data signal at a bit rate B (B=A×M) through the same line. The communication terminal apparatus includes a signal regenerating unit, a management signal converting unit, a timing control unit, and a data signal obtaining unit. The signal regenerating unit regenerates a signal transmitted through the line as a signal of a bit rate C (C=A×N). The management signal converting unit converts N bits of the regenerated signal into the management signal of one bit. The timing control unit controls timing for obtaining a data signal based on the management signal. The data signal obtaining unit obtains the data signal according to timing control of the timing control unit.

Abstract: A device for phase distortion compensation across an optical beam is provided. The device is a part of an optical receiver, which can be used in free space optical communications, remote sensing, optical imaging and others. 2M inputs of the combiner interfere with each other via a system of tunable coupled waveguides. The phases in interleaved waveguides of the combiner are adjusted to maximize the resulting output signal. The combiner may be used for coherent communication in combination with a balanced 90° hybrid. Integrated solutions for the proposed device are provided.

Abstract: A system and method for increasing transmission distance and/or transmission data rates using tedons and an encoding scheme to reduce the number of ones in a data signal is described. For example, the method for increasing transmission distance and transmission data rate of a fiber optical communications link using tedons includes the steps of encoding a data signal to be transmitted using an encoding scheme that reduces a number of ones in the data signal, transmitting the encoded data signal over the fiber optical communications link, receiving the encoded data signal and decoding the encoded data signal.

Abstract: An optical field receiver comprises an optical branching circuit for branching a received optical multilevel signal into first and second optical signals, a first optical delayed demodulator for performing delayed demodulation on the first optical signal at a delay time T (T=symbol time), a second optical delayed demodulator for performing delayed demodulation on the second optical signal at the delay time T with an optical phase difference deviating from the first optical delayed demodulator by 90°, first and second optical receivers for converting each of the delayed demodulation signals representing x and y components of complex signals output from the first and second delayed demodulators into first and second electrical signals, and a field processing unit fort generating a first reconstructed signal representing an inter-symbol phase difference or a phase angle of a received symbol from the first and second electrical signals for each symbol time T.

Abstract: A device for processing of an optical input signal includes at least a first data signal. A first optical resonator provides a reference signal by optical filtering of the optical input signal. The first optical resonator is matched with a predetermined reference wavelength of the first data signal. A second optical resonator provides a sideband signal by optical filtering of the optical input signal. The second optical resonator is non-matched with the predetermined reference wavelength of the first data signal. An optical combiner combines the sideband signal with the reference signal to form an optical output signal.

Abstract: An optical beam combiner is provided, which allows efficient collection of light for various applications: non-line of sight and free space optical communications, remote sensing, optical imaging and others. A multitude of optical beam portions is captured by a space diversity receiver that includes an optical beam combiner, which has a tree-like topology with interconnected waveguides, electro-optic phase shifters, and directional couplers. For each of the beam portions the phase of the phase shifter and the coupling ratio of coupler in the optical beam combiner are tuned sequentially to maximize the final output power in the final optical waveguide. A portion of the final output beam is used for the power detection and forming a feedback signal for the phases and coupling ratios adjustment. The data or information is recovered from the received final optical beam using coherent detection.

Abstract: An optical beam combiner is provided, which allows efficient collection of light for various applications: non-line of sight and free space optical communications, remote sensing, optical imaging and others. A multitude of transverse scattered optical beam portions is captured by the multi-aperture array positioned perpendicular to the beam projection direction. These beam portions are combined first into a single optical waveguide with minimal loss of power. This is achieved by modulating the beam portions phase and coupling ratio of couplers in the optical beam combiner tuned to maximize the final output power. The data is recovered from the received optical beam using coherent detection.

Abstract: An optical device is provided with first and second inputs. A first coupler coupled is coupled to the first input and produces at least a first and second output. A second coupler is coupled to the second input and produces at least a first and second output. A third coupler is coupled to the first output of the first coupler and to the first output of the second coupler. A fourth coupler is coupled to the second output of the first coupler and to the second output of the second coupler. First and second crossing waveguides are provided with an angle selected to minimize crosstalk and losses between the first and second cross waveguides. The first crossing waveguide connects one of the first or second outputs from the first coupler with an input of the fourth coupler. The second crossing waveguide connects one of the first or second outputs from the second coupler with an input of the third coupler. A first phase shifter is coupled to the first and second waveguides.

Abstract: It is possible to perform reset free operation in devices having polarization state controllers by employing specific sequences of phase shifters and couplers. In particular, sequences comprising a coupler/phase shifter/coupler or phase shifter/coupler/phase shifter formed in, for example, a semiconductor substrate, e.g. silicon substrate, is used to form the polarization state controller. For example, a sequence functions as a quarter wave plate equivalent while two combined sequences function as a half wave plate. Moreover, sequences functioning as wave plates more general than quarter wave plates are advantageously employed. Control of the couplers and phase shifters of these sequences yield reset free or reset free, fully deterministic operation.

Abstract: A clock extraction apparatus capable of supporting even a high-speed optical signal with a simple arrangement is proposed. A ?-phase shifted fiber Bragg grating (?-phase shifted FBG) 10 is adjusted in such a manner that a phase difference between reflected light waves resulting from two sub-FBGs 1 and 2 will be ? and time delay ?t between the reflected light waves will be smaller than the bit period Tb of an optical signal. An optical signal is input to the ?-phase shifted FBG. Pulses are produced in a reflected light wave that is output from the ?-phase shifted FBG 10, the pulses appearing at rising and falling edges of an NRZ signal. The reflected light wave is passed through a light circulator 11 and is converted to an electrical signal by a photosensor 12. A clock signal is generated (produced) by passing the electrical signal into a narrow-band filter 13.

Abstract: Apparatus for demultiplexing a wavelength division multiplexed optical signal comprising a plurality of signals each having a different wavelength. The apparatus comprises a demultiplexer sub-assembly and a multi-channel receiver optical sub-assembly. The demultiplexer sub-assembly comprises a filter block sub-assembly for splitting the input optical signal. The receiver optical sub-assembly comprises an array of photo detectors for converting the optical signals from the filter block sub-assembly into electrical signals. The electrical signals are amplified by amplifier ICs and transmitted through electrical leads. The demultiplexer sub-assembly and the multi-channel receiver optical sub-assembly are actively aligned and fixed together.

Abstract: A transmitter (11) emits a single wavelength optical signal and transmits this as a wavelength channel (13) in a compound multiplex signal through the WDM network. The receiver (12) selects the single wavelength optical signal (21) from the compound multiplex signal using a band-pass filter. A wavelength fit detector (15) determines a feedback signal by correlating variations of the amplitude of the received signal with variations of the traffic density. This feedback signal is then returned to the transmitter (11) via a back channel (16) and serves to tune the wavelength of the single wavelength optical signal.

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 transmitting device includes a housing, a multichannel transmitter optical subassembly, a microcontroller, and a DVI connector. The housing has only one optical port, where the only one optical port is adapted to receive only one optical fiber. The multichannel transmitter optical subassembly is mechanically associated with the housing. The microcontroller is electrically associated with the multichannel transmitter optical subassembly. The DVI connector is mechanically associated with the housing. The transmitting device is adapted to convert at least four electrical TMDS signals into optical paths that are transmittable over the only one optical fiber. A receiving device is similar to the transmitting device, however, in contrast to the transmitting device, the receiving device includes a multichannel receiver optical subassembly, and wherein the receiving device is adapted to convert multiple colored wavelengths into at least four electrical TMDS signals.

Abstract: A system comprises an optical network terminal (ONT) that terminates an optical fiber link of an optical network to provide an optical network interface. The ONT may include an optical module that receives optical signals via the optical fiber link and converts the optical signals to electrical signals and an optical media access control (MAC) unit that converts at least some of the electrical signals to data units. The optical MAC unit may be selectively configurable to support a plurality of optical network protocols. For example, the optical MAC unit is selectively configurable to support two or more of BPON protocol, a GPON protocol, a GEPON protocol and an active Ethernet protocol. In one instance, the optical MAC unit is selectively configurable to support at least one active optical network protocol and at least one passive optical network protocol.

Abstract: A system comprises an optical network terminal (ONT) that provides an interface to a passive optical network (PON). The ONT is coupled to a subscriber gateway device via at least one cable. The ONT may be located outside a subscriber premises while the subscriber gateway device may be located within the subscriber premises. The ONT converts optical signals received from PON to electrical signals and transmits the electrical signals to the subscriber gateway device without performing any MAC layer functions. The subscriber gateway device includes an optical media access control (MAC) unit that converts the electrical signals into MAC layer signals and a gateway unit that distributes the MAC layer signals to one or more subscriber devices. In this manner the MAC and gateway layer functions are relocated from the ONT to the subscriber gateway device.

Abstract: An apparatus and method for use in an adaptive optical equalizer including, in one embodiment an optical equalizer having an input and output coupled to receive an incoming optical signal and configured to generate an output optical signal by phase modulation and/or amplitude modulation of the receive optical signal in response to electronic control signals. A photodiode is configured to receive the output optical signal and generate an representative current signal. A control signal generator is configured to generate the electronic control signals in accordance with predetermined criteria and in response to the representative current signal from the photodiode. An interferometer is connected to receive the incoming and output optical signal from the optical equalizer, the differential amplifier is configured to receive electronic versions of outputs from the interferometer for generating a difference signal and supplying the difference signal to the control signal generator.

Abstract: The invention relates to clock recovery in optical communication systems. Optical clock frequencies are recovered from a plurality of optical channels by using a single optical resonator. The optical resonator is matched with the carrier frequencies and the sideband frequencies of the data signals sent at different channels. The separation range of the optical resonator is selected such that the clock frequency of at least one data signal is substantially equal to the separation range of the optical resonator multiplied by an integer greater than or equal to two. The method according to the invention allows the use of different clock frequencies at different optical channels. Furthermore, the method provides considerable freedom to select the spectral positions of the optical channels.

Abstract: A receiver for an OTDM/PDM pulse train (10) in which the pulses (12) have alternating polarizations (P1, P2) has a polarization insensitive optical switch (16; 161, 162, 163, 164) for isolating optical pulses (10?) within the pulse train (10), and a polarization selective element (17) for separating from the isolated pulses (10?) at least one component that has a single polarization. This allows to considerable relax the constraints posed on the switch since components in the isolated pulses that result from interchannel interference can, at least to a large extent, be eliminated by the subsequent polarization selective element (17).

Abstract: An optical receiving apparatus sets, efficiently and optimally, a delay interferometer and a variable wavelength dispersion compensator in the apparatus.

Abstract: In an over-sampled maximum-likelihood sequence estimation (MLSE) receiver system, the optimal sample spacing is determined for a variety of conditions. In an illustrative implementation, the system includes an optical filter for tightly filtering an incoming optical data signal with an on-off-keying (OOK) non-return-to-zero (NRZ) format, followed by an optical-to-electrical converter, an electrical filter, a sampler, and a MLSE receiver. The sampler samples the filtered electrical data signal twice each bit period with unequal sample spacings. For wide optical filtering bandwidths, the optimal sample spacing occurs at less than 50% of a bit period. For narrow bandwidths, the optimal sample instances occur closer to the maximum eye opening.

Abstract: Methods and systems for PMD compensation in an optical communication system are implemented by transmitting multiple optical signals through a common optical conduit to an optical compensator that adjustably rotates the polarization states of the multiple optical signals and transmits the rotated optical signals to an optical receiver. The receiver, upon sensing an excessive error condition, commands the optical compensator to change the polarization state of rotation, which changes the PMD profile of the received optical signals.

Abstract: A system and method for superheterodyne detection in accordance with the invention. The system comprises a first conversion unit for performing a first heterodyne operation on an optical input signal to generate an electrical IF signal. A second conversion unit is electrically or optically coupled to the first conversion unit. The second conversion unit performs a second heterodyne operation to generate an electrical output signal suitable for signal processing.

Abstract: A transmitting and receiving device, in which the received signal which is produced by the receiving device has only a small amount of crosstalk. This object is achieved by providing a transmitting and receiving device having a transmitting device for producing a transmission signal, a receiving device for producing a received signal, and a compensation device which is connected to the transmitting device and to the receiving device and which at least reduces any crosstalk which is produced by the transmitting device in the receiving device.

Abstract: In an optical communication-use receiving circuit of the present invention, the pulse width of the received pulse which is a binary signal corresponding to the signal optical pulse is specified by using an integration circuit and a trigger generating circuit. If the pulse width of the received pulse is not shorter than a predetermined value, a signal having a fixed pulse width is outputted as an output signal from a one-shot pulse generating circuit, so that a pulse having a constant pulse width corresponding to the specified communication speed is outputted. Accordingly, if the pulse width deriving from the signal optical pulse is larger than a certain value, the communication is deemed as a low-speed communication, and a pulse having a constant pulse width corresponding to the communication speed is outputted. As a result, it is possible to realize a small-size receiving circuit and a small-size electronic device which require no external switching-over terminal.

Abstract: A system and method for increasing transmission distance and/or transmission data rates using tedons and an encoding scheme to reduce the number of ones in a data signal is described. For example, the method for increasing transmission distance and transmission data rate of a fiber optical communications link using tedons includes the steps of encoding a data signal to be transmitted using an encoding scheme that reduces a number of ones in the data signal, transmitting the encoded data signal over the fiber optical communications link, receiving the encoded data signal and decoding the encoded data signal.

Abstract: A multiplexer of a transmission section generates a clock signal by multiplying a reference clock signal of a digital image signal by a predetermined number ‘K’. A parallel digital image signal is converted into a serial digital signal on the basis of the clock signal, and the serial digital signal is converted into an optical signal in an optical transmission section for transmitting. A demultiplexer extracts a reception clock signal from a serial digital reception signal which is converted into an electric signal in an optical reception section of a reception section, the serial digital reception signal is converted into a parallel signal and a signal corresponding to the parallel digital image signal on the basis of the reception clock signal, and a clock signal corresponding to the reference clock signal is recovered by multiplying the reception clock signal by ‘1/K’.

Abstract: A small, low cost, low power-consumption optical receiver transmits signals at a high bit rate of approximately 10 Gbps over a long distance of 100 km or longer without chromatic dispersion compensation. An optical filter with a variable filtering wavelength is provided in the optical waveguide. A frequency-modulated signal light is inputted into the waveguide and transferred to the through port and the drop port thereof. The filter limits the frequency-modulated signal light to a predetermined frequency band and converts the said light to an intensity-modulated signal. The first and second converters provided at the through and drop ports to convert the first and second components of the intensity-modulated signal to electric signals, respectively. The filtering wavelength of the filter is controlled using the electric signals from the first and second converters. The input signal is regenerated from the electric signal of the second converter.

Abstract: A communication system includes an optical transmitter which is differentially driven and an optical receiver that outputs a differential signal. The optical transmitter creates the differential drive signal from an input signal and delivers the differential drive signal to a laser. The differential drive signal is generated with a transformer and RF chokes for floating the laser above ground. The signal detected by the receiver is input as a differential signal to a transformer which then passes the signal through amplifiers and a filter. The optical communication system provides an increased spurious-free dynamic range which is well suited for RF signals and other analog signals.

Abstract: A system and method for detecting digital symbols carried in a received optical signal. The system comprises a functional element operative to receive a stream of samples of an electrical signal derived from the received optical signal and to evaluate a non-linear function of each received sample, thereby to produce a stream of processed samples. The system also comprises a detector operative to render decisions about individual symbols present in the received optical signal on the basis of the stream of processed samples. In an embodiment, the non-linear function computes substantially the square root of each received sample.

Abstract: A transmitter formed of two or more light-emitting sections such as LEDs, which are physically arranged in a predetermined manner, is disposed in the real world object, and each light-emitting section transmits data by flashing at a flashing pattern representing the transmission data of a predetermined bit length. A receiver, on the other hand, includes a photoreceiving section formed from a two-dimensional photoreceiving surface, decodes the transmission data on the basis of the photoreceived flashing pattern, and recognizes the spatial information of an object on the basis of the flashing position on the two-dimensional photoreceiving surface. Therefore, information, such as an ID, can be obtained from the object in the real world, and also, the spatial position of the object can be recognized at the same time.

Abstract: In an adaptive optics module, wavefront sensing and data detection are implemented in a single device. For example, an optical-to-electrical converter converts a data-encoded optical beam to an intermediate electrical signal, which contains both the data encoded in the beam and also wavefront information about the beam. The data and wavefront information are later separated, for example by frequency filtering.

Abstract: An optical receiver circuit is constructed to be immune to interference from external interference signals. The optical receiver circuit includes a differential amplifier having an optical reception device connected to one input of the differential amplifier. The optical receiver circuit also includes an electrical element for simulating the electrical behavior of the reception device in the illumination-free state. The electrical element is connected to the other input of the differential amplifier.

Abstract: A transmission apparatus that receives an optical signal by selecting any one of a plurality of provided optical signal transmission paths through protection control is configured to include a plurality of optical signal outputting sections that output the optical signals transmitted through said optical signal transmission paths respectively as optical signals having wavelengths that are different from each other, a wavelength selective optical switch capable of selectively outputting light of a wavelength corresponding to any one of the optical signals coming from the optical signal outputting sections on the basis of the frequency of a controlling frequency signal, and an optical switch controlling section that supplies said controlling frequency signal to the wavelength selective optical switch so as to output the optical signal coming from the optical signal transmission path side that is selected by said protection control among the optical signals coming from the optical signal outputting sections.

Abstract: An optical device is provided with first and second inputs. A first coupler coupled is coupled to the first input and produces at least a first and second output. A second coupler is coupled to the second input and produces at least a first and second output. A third coupler is coupled to the first output of the first coupler and to the first output of the second coupler. A fourth coupler is coupled to the second output of the first coupler and to the second output of the second coupler. First and second crossing waveguides are provided with an angle selected to minimize crosstalk and losses between the first and second cross waveguides. The first crossing waveguide connects one of the first or second outputs from the first coupler with an input of the fourth coupler. The second crossing waveguide connects one of the first or second outputs from the second coupler with an input of the third coupler. A first phase shifter is coupled to the first and second waveguides.

Abstract: The present development includes a first element of an optical fibre entrance by which an information carrying signal is transmitted, an optical detector block, a non-linear equalizer block and a final processor block. The development includes an electrical non-linear equalizer block, connecting the output of the optical detector block and the input of the final processor block that compensates the quadratic non-linear characteristic of the optical detector block. Both blocks thus may present a more linear joint characteristic between the electrical field envelope of the information carrying signal in the optical fibre and the electrical signal. Consequently, the final processor block can compensate, in a more effective form, for the linear distortions that the information carrying signal suffers in the transmission through the fibre.

Abstract: The present invention provides a system and method of optical communications that utilize coherent detection technique and optical orthogonal frequency division multiplexing for phase encoded data transmission. In particular the invention addresses a device and method for digital polarization compensation of optical signals with up to 100 Gb/s transmission rate received via an optical link. The polarization compensation operates in two modes: acquisition mode and tracking mode. The polarization recovery is performed at the receiver side using the received digital signal conversion into frequency domain and separate reconstruction of the polarization state in each spectral component.

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: A coherent optical receiver of the invention combines local oscillator light having orthogonal polarization components in which the optical frequencies are different to each other, and received signal light, in an optical hybrid circuit, and then photoelectrically converts this in two differential photodetectors. Then this is converted to a digital signal in an AD conversion circuit, and computation processing is executed in a digital computing circuit using the digital signal, to estimate received data. At this time, the optical frequency difference between the orthogonal polarization components of the local oscillator light is set so as to be smaller than two times the signal light band width, and larger than a spectrum line width of the signal light source and the local oscillator light source. As a result, it is possible to realize a small size polarization independent coherent optical receiver that is capable of receiving high speed signal light.

Abstract: An optical device extracts an information bearing sideband such as an FSK or SCM signal (label) from a composite signal that includes the sideband and an orthogonally modulated signal such as an intensity modulated signal (payload) by employing polarization beam splitting and polarization transformation. Polarization transformation is accomplished by splicing the optical signal into a polarization maintaining fiber at a desired angle so that it is separated into two orthogonal polarizations that experience differential group delay in the fiber. The fiber is characterized by a beat length Lbeat and the fiber is designed to have a length substantially equal to (Lbeat×fc)/2?f, wherein the sidebands of the composite signal are separated by a wavelength difference ?f and fc is the nominal center frequency of the composite signal. This device has been shown to be useful for extracting GMPLS LSC level wavelength labels from either an FSK/IM composite signal or an SCM/IM composite signal.

Abstract: The invention discloses a digital adjusting method for an optical receiver module, and the method implements real-time monitor of parameters, on-line adjustment and non-linear compensation. The digital optical receiver module includes elements as follow: a voltage output circuit of optical power detection 24, a DC/DC voltage boost circuit 22 and a bias voltage adjusting unit which is consisted of an optical-electronic conversion circuit 21; a digital adjusting unit 25, an analog-digital converter (A/D converter) 26 and a memory 27. The digital adjusting unit 25 makes on-line adjustment and implements temperature compensation and dark current compensation of the optical receiver module. The A/D converter 26 monitors the optical power, the working temperature and the bias voltage of the optical detector in real time. The memory 27 stores parameters of the optical receiver module for comparison with a detected optical power and measured temperature etc. and for on-line interrogation.

Abstract: The disclosure relates to surface plasmon-polariton waveguides, which can guide ultra-long range surface plasmon-polariton waves. The attenuation of an ultra-long range surface plasmon-polariton waves is much lower than the attenuation of the conventional long range surface plasmon-polariton waves guided with the same kind of metal film or metal strip at the same plasmon-polariton frequency. An exemplary ultra-long range surface plasmon-polariton waveguide disclosed in this disclosure comprises a metal layer, such as a metal film or finite width metal strip, intermediate dielectric layers adjacent to the metal layer, and outer cladding dielectric material. The intermediate dielectric layers redistribute the electromagnetic energy distribution of the surface plasmon-polariton waves so that less of the energy propagates in the metal layer. Therefore, the attenuation of the surface plasmon-polariton wave is reduced.

Abstract: An optical link module of the present invention for connecting light beams by deflection and including light-emitting devices arranged in a planar manner; an optical fiber bundle that is an optical waveguide for receiving the light beams from the light-emitting devices, and an optical turn which includes a plurality of aspherical lenses which are disposed between the light-emitting devices and the optical fiber bundle and are formed while corresponding to the number of the light-emitting devices and the number of optical fibers.

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: In an optical signal monitoring method in wavelength multiplexing and an optical network, an area corresponding to a characteristic pattern of an eye pattern of an optical signal to be monitored, which characterizes a deterioration, is extracted from a database storing a map which associates a quality deterioration factor and deterioration amount of the optical signal with the characteristic pattern of the area of the eye pattern of the optical signal. The extracted pattern is collated with the map stored in the database to monitor the quality deterioration factor and deterioration amount of the optical signal, an occurrence time of a deterioration, duration of a deterioration, a deterioration occurrence cycle, and a deterioration duration cycle. An optical signal monitoring apparatus is also disclosed.