Abstract: An optical receiver includes an optical amplifier configured to amplify an input optical signal and output an amplified optical signal; and a light receiving element configured to convert the amplified optical signal into an electrical signal and output the electrical signal, and the optical amplifier controls an output-level of the amplified optical signal according to a wavelength of the input optical signal.

Abstract: The present invention relates generally to the transport and processing of optical communication signals. More specifically, the present invention relates to systems and methods for the polarization insensitive coherent detection of optical communication signals with Brillouin amplification of the associated signal carrier and the polarization division multiplexed transmission of optical communication signals without polarization tracking at the associated receiver(s).

Abstract: In various exemplary embodiments, the present invention provides coherent non-differential detection systems and methods for the detection of optical communication signals by the Brillouin fiber amplification of an optical communication signal carrier, the coherent non-differential detection systems including: a Sagnac loop including a single-mode fiber span; a fiber span with negligible birefringence (i.e. a spun fiber span or the like); or a fiber loop with negligible birefringence (i.e. a spun fiber loop or the like).

Abstract: Various embodiments of a coherent receiver including a widely tunable local oscillator laser are described herein. In some embodiments, the coherent receiver can be integrated with waveguides, optical splitters and detectors to form a monolithic optical hetero/homodyne receiver. In some embodiments, the coherent receiver can demodulate the full phase information in two polarizations of a received optical signal over a range of optical wavelengths.

Abstract: Disclosed is a multimedia data receiver using an optical cable that can receive multimedia data such as an image, voice and control signal whose media are different from each other through an optical transmission medium such as plastic or glass optical cables in a short or long distance area.

Abstract: An optical DPSK signal demodulator includes a signal separator that separates an optical signal into an input optical signal and an output optical signal in a signal optical path. First and second reflectors are provided at a predetermined interval and reflect the optical signals with a predetermined time delay to have substantially the same intensity. A phase shifter is provided between the first and second reflectors and configured to allow the optical signals reflected from the first and second reflectors to have a phase difference.

Abstract: Apparatus and methods for noise-feedback controlled optical systems are disclosed. In one aspect, an apparatus includes a receiver adapted to receive an optical signal and to convert the optical signal to a corresponding electrical signal, and a control circuit coupled to the receiver. The control circuit includes a monitoring component adapted to monitor a noise level of at least a portion of the electrical signal and to adjust a gain of the receiver based on the noise level. In an alternate aspect, an optical system includes a transmitter, a receiver, and a monitoring component adapted to monitor a noise level of at least a portion of the electrical signal and to adjust at least one of an amplification of the transmitter and a gain of the receiver based on the noise level.

Abstract: A linear phase demodulator/down-converter comprises an optical amplitude modulator for modulating the amplitude of an optical input signal, a photo-detector, a loop filter and an optical phase modulator provided with a light source. The optical phase modulator/down-converter provides optical down conversion, optical up conversion, or a combination thereof. The photo-detector can be a balanced photo-detector. Linear phase demodulation and/or down conversion is performed completely in the optical domain.

Abstract: A light receiving circuit includes: a 1-bit delay interferometer; two photodiodes; and a demodulating circuit for converting current signals of the photodiodes into voltages to thereby demodulate signals that have been modulated by return-to-zero differential phase shift keying, the demodulating circuit including a differential transimpedance amplifier, in which the differential transimpedance amplifier includes a level adjusting circuit that has a function of adjusting levels of a positive phase signal and a negative phase signal of two feedback closed loops.

Abstract: Techniques, devices and systems based on optical receivers with controllable transfer function bandwidth and gain imbalance.

Abstract: Apparatuses, systems, and methods are disclosed that provide for an agile coherent optical modem that can generate agile RF waveforms and data rates on a generic opto-electronic hardware platform. An “agile coherent optical modem” [ACOM] approach to optical communications by employing a software configurable and adaptive technologies to the transport system. The ACOM generate agile RF waveforms and data rates on a generic opto-electronic hardware platform. By employing advanced communication techniques to the optical domain such as wavelength agility, waveform agility, and symbol rate agility, it is possible to enable robust optical communications. The ACOM allows for the transport capacity of a communications link to be varied, thereby accommodating variations in transport conditions, range, opacity, etc.

Abstract: An optical receiver includes: a converting unit that converts an optical signal into an electrical signal; an amplifying unit that amplifies the electrical signal; a regenerating unit that regenerates the amplified electrical signal; a correcting unit that performs correction of an error included in the regenerated electrical signal; a monitoring unit that performs monitoring of an optical current flowing through the converting unit; and a control unit that calculates a decision threshold based on a result of the correction and a result of the monitoring.

Abstract: Method and apparatus for data recovery in optical transmission systems include parallel detection subcircuits for determining output values of sequentially provided optical data bits such that sequentially provided optical data bits are alternately processed by respective ones of the parallel detection subcircuits. For example, in one embodiment of the present invention, clock values to be used for timing provided to the first parallel detection subcircuit are 180° out of phase with clock values provided to the second parallel detection subcircuit, such that the first parallel detection subcircuit and the second parallel detection subcircuit alternately process input optical data bits according to odd valued clock signals and even valued clock signals. Furthermore, the outputs of the parallel detection subcircuits are connected crosswise to provide control signals for their parallel counterparts.

Abstract: A small size and low cost optical receiving apparatus, which can stably demodulate the signal, lights in accordance with the differential M-phase shift keying (DMPSK) system. An optical receiving apparatus comprises a light branching unit for branching the differential M-phase shift keying signal beam into four signal light beams, a delay adjusting unit giving a delay time difference of one symbol between a first signal light beam and a second signal light beam and between a third signal light beam and a fourth signal light beam, a demodulating unit for outputting a least two demodulated light signals through respective interferences between the first signal light beam and the second signal light beam, and between the third signal light beam and the fourth signal light beam on one plane which is not parallel to any signal light beam, and at least two optical detectors for converting at least two light signals into electrical signals.

Abstract: An OCDMA system is disclosed that provides for storage and retrieval of OCDMA data while maintaining OCDMA encoding and signaling information. The system includes a wavelength demultiplexer that optically receives an OCDMA signal having a plurality of wavelengths of light. A plurality of light detectors is optically interconnected with the wavelength demultiplexer, with each of the light detectors being associated with a unique wavelength of light. Each of the light detectors respectively communicates with a plurality of storage volumes. For example, each storage volume is associated with a unique wavelength of light and is configured for storing optical data electronically converted from an optical data stream having a unique wavelength of light. Such a process may substantially eliminate the need for OCDMA conversion during electronic storage of the OCDMA data. Stored OCDMA data may be rapidly retrieved and configured as an OCDMA signal because OCDMA coding is maintained.

Abstract: It is provided a radio oscillating system for oscillating a radio signal. The system has an optical modulator for oscillation, a modulating means for inputting a modulating signal of a frequency of fm into the optical modulator to modulate a carrier wave so as to interpose sideband waves onto the carrier wave at positions shifted with respect to the frequency of the carrier wave by the frequency “fm”; and an optical receiver for oscillation for receiving beam from the optical modulator and converting the beam into an electrical signal. The system further has a radiating means for radiating radio signal of a frequency of 2fm based on the electrical signal. An input voltage Vp-p applied on the optical modulator is 1.0 times or more and 1.99 times or less of a half-wavelength voltage V? of the optical modulator.

Abstract: An automatic threshold voltage adjustment circuit, a method of automatically adjusting threshold voltage and an optical receiver for an optical communication system. In one embodiment, the circuit includes: (1) an amplitude detector configured to detect an amplitude of a received optical signal, (2) a variable resistor coupled to the amplitude detector and including a field-effect transistor configured to operate in a triad mode to provide a resistance that varies substantially linearly based on the amplitude and (3) an operational amplifier coupled to the variable resistor and configured to apply a variable gain based on the resistance to an input threshold voltage to yield an adapted threshold voltage.

Abstract: A micro-optic dual beam-splitter assembly comprises at least two beam-splitter optical filters and at least one photoreceptor. Each of the beam-splitter optical filters comprises an optical substrate having at least a coated or uncoated optical tap surface and a filter surface carrying a thin-film optical filter. The thin-film optical filters are substantially normal to the optical path from an optical signal source. Each of the optical tap surfaces is operative as an optical beam splitter to tap off an optical tap signal. The one or more photoreceptors are arranged to receive both or at least one of the optical tap signals. The tap signals comprise a portion of the optical signals passed along the optical path to the optical filter chips. The filter chips are cooperatively transmissive to an optical signal output port of a selected set of wavelengths received from the optical signal source along the optical path, and are reflective of other wavelengths.

Abstract: An optical receiver is provided as a device capable of detecting a small optical power with satisfactory accuracy and detecting the optical power in a wide dynamic range. In the optical receiver a bias generator applies a variable voltage to an avalanche photodiode (APD). First and second current sensors generate first and second detected signals according to a photocurrent. A controller calculates an optical power, using either one of the detected signals. The first current sensor includes a current mirror circuit and generates a first detected signal by measuring an electric current proportional to the photocurrent. The second current sensor is disposed between the bias generator and the current mirror circuit, and the maximum of the photocurrent detectable by this second current sensor is greater than the maximum of the photocurrent detectable by the first current sensor.

Abstract: An optical code division multiple access communication system using a processor processes at least one collimated input beam which has been modulated with a data signal to produce multiple time-delayed output beams. The multiple time-delayed output beams are spatially distributed and independently phase shifted. An integration lens receives the phase modulated output beams and reintegrates the phase modulated output beams into a single encoded beam with a time series chip sequence. The integrated encoded beam is transmitted. A receiving system includes a processor to process the encoded collimated light beams received from a transmitter to produce multiple time-delayed output beams. The multiple time-delayed output beams are spatially distributed and independently phase shifted. An integration lens receives the phase-shifted output beams and reintegrates the phase-shifted output beams into a single decoded beam.

Abstract: Methods and apparatus for monitoring the power level of one or more optical emitters are provided. In some embodiments, optical signals from two or more optical emitters are directed at different regions of a photo detector. The photo detector may include two or more spaced contacts that are adapted to receive different contributions of photo current from each of the optical signals. By monitoring the photo currents in the two or more spaced contacts, a measure of the optical power of each of the optical signals may be determined.

Abstract: Systems and methods for operating transponders that automatically accommodate multiple received signal types. The different signal types may include different clients such as, e.g., SONET/SDH, G.709, 10 Gigabit Ethernet, etc. as well as different data rates. A transponder can automatically detect the client signal type and data rate and respond by processing the received signal appropriately, notifying a control processor, and invoking an appropriate performance monitoring method. This maximizes the network operator's flexibility and ease of configuration.

Abstract: A detector module for the reception of optical signals (SE) including a module housing having at least one electrical and at least one optical bushing, at least one electrical assembly connected to the electrical bushing, and at least one optical assembly connected to the optical bushing, the electrical and optical assemblies being arranged within the module housing, the optical and electrical assemblies being connected to one another via at least one optical interface, and the electrical assembly having at least one photodiode for converting the optical output signals of the optical assembly into electrical signals. The optical assembly has at least one collimator and on the output side transmits at least one beam comprising collimated electromagnetic rays running parallel to one another via a free-radiating connection as optical interface to the electrical assembly, and the electrical assembly receives the beam from the optical assembly via the free-radiating connection.

Abstract: Systems and methods for encoding information in the topology of superpositions of helical modes of light, and retrieving information from each of the superposed modes individually or in parallel. These methods can be applied to beams of light that already carry information through other channels, such as amplitude modulation or wavelength dispersive multiplexing, enabling such beams to be multiplexed and subsequently demultiplexed. The systems and methods of the present invention increase the number of data channels carried by a factor of the number of superposed helical modes.

Abstract: A dispersion compensation type optical signal receiving apparatus includes: an APD element for converting input signal light inputted from a transmission line into an electric signal; an amplifying device constituted with a preamplifier circuit and a limit amplifier circuit, which amplifies the electric signal converted by the APD element; an EDC IC for compensating the dispersion in the transmission line electrically; and a clock/data reproducing circuit for reproducing the clock and data signal contained in the input signal light, wherein there is provided a VOA for limiting the amplitude of the input signal light inputted to the APD element and an attenuation amount controlling circuit for controlling the attenuation amount of the VOA in accordance with the bias current of the APD element.

Abstract: A method for upgrading an optoelectrical system includes securing a transmitter to a line card, wherein the line card comprises an optoelectrical connector. It also includes coupling the transmitter to the connector, wherein the connector comprises an embedded fiber configured to be coupled to the transmitter. In addition, the method includes inserting a pluggable form factor module comprising a receiver, an input port, and an output port into a cage secured to the line card. Further, the method includes coupling the pluggable form factor module to the connector such that an optical signal transmitted by the transmitter propagates in an optical line of sight between the embedded fiber of the connector and the output port. The connector comprises electrical contacts that are configured to be coupled to the module such that the receiver can convert optical signals received at the input port into electrical signals and transmit the electrical signals to the line card via the connector.

Abstract: A system and method for demodulating an optical differential-phase-shift-keyed (DPSK) input signal using a Fabray-Perot etalon filter. In one embodiment the system receives a transmitted wavefront from the etalon filter and uses a detector to generate an electrical waveform from the transmitted wavefront. A comparator is used to receive an output from the detector and to generate a signal in accordance with each phase shift (i.e., bit transition) in the optical DPSK input signal. A latching flip-flop receives an output from the comparator and generates a digital signal representative of the bit pattern of the DPSK input signal. The system and method does not require the precisely matched dual optical paths of a Mach-Zehnder interferometer, and therefore is substantially less susceptible to thermal effects that could influence the operation of a conventional Mach-Zehnder interferometer in DPSK demodulation operations.

Abstract: An optical transmission system is provided in which the optimum operating point of a Mach-Zehnder interferometer, matched to the optical frequency of the light source on the transmitting side, can be set.

Abstract: An apparatus and method for detecting an output power level of an optical receiver, in order to hold output signal levels constant over changing input optical levels. A photodetector detects an optical signal, and a current from the photodetector is applied an amplifier. The amplifier may be either a differential trans-impedance amplifier, or a dual trans-impedance amplifier coupled to a differential output amplifier. An output of the amplifier is applied o a signal detector, wherein an output signal of the signal detector is an indication of an output power level of the optical receiver.

Abstract: A DQPSK receiver extracts first and second phase modulation components from an input optical signal, and respectively converts the extracted components into the first and second data signals. The DQPSK receiver extracts a clock signal from one of the data signals, and produces an inverted clock signal by inverting the extracted clock signal. Then, the DQPSK receiver latches the first data signal by using the extracted clock signal or the inverted clock signal, and latches the second data signal by using the extracted clock signal.

Abstract: An interferometer includes an optical beam splitter that splits an input optical signal into a first optical signal propagating in a first optical path comprising free space and a second optical signal propagating in a second optical path comprising a dielectric medium. A differential delay delays the second optical signal relative to the first optical signal by a differential delay time that is proportional to at least one of a temperature and a refractive index of the dielectric medium. A temperature controller in thermal contact with the dielectric medium changes the temperature of the dielectric medium to control at least one of thermal expansion/contraction and a temperature dependent change in the refractive index of the dielectric medium, thereby changing the differential phase delay.

Abstract: Apparatus and system for transmitting and receiving optical code division multiple access data over an optical network. The apparatus comprises a spectral phase decoder for decoding the encoded optical signal to produce a decoded signal, a time gate for temporally extracting a user signal from the decoded signal, and a demodulator that is operable to extract user data from the user signal. The system preferably comprises a source for generating a sequence of optical pulses, each optical pulse comprising a plurality of spectral lines uniformly spaced in frequency so as to define a frequency bin, a data modulator associated with a subscriber and operable to modulate the sequence of pulses using subscriber data to produce a modulated data signals and a Hadamard encoder associated with the data modulator and operable to spectrally encode the modulated data signal to produce an encoded data signal.

Abstract: A demodulator includes: a splitter that branches a differential phase shift keying optical signal into a first branched optical signal passing through a first optical path and a second branched optical signal passing through a second optical path; a multiplexer that multiplexes the first branched optical signal having passed through the first optical path and the second branched optical signal having passed through the second optical path and makes interference between the first branched optical signal and the second branched optical signal; and a double refraction medium that reduces difference between phase differences between each polarized wave between the first branched optical signal and the second branched optical signal multiplexed by the multiplexer.

Abstract: When operation keys are operated, a light-emitting device outputs an infrared signal corresponding to the operated operation keys. The infrared signal is applied to a light-detecting device. In response to the applied infrared signal, the light-detecting device generates a detected signal and supplies the detected signal to an amplifying circuit. The amplified detected signal from the amplifying circuit is decoded by a decoding circuit into a data code, which is supplied through an interface circuit to a computer. Based on control data supplied as the data code to the computer, the computer controls a projector to perform a process of displaying images page by page, for example.

Abstract: An interferometer comprises a delay element and a phase shift element. The delay element delays an optical DQPSK signal by one-symbol time. The phase shift element shifts the optical DQPSK signal by ?/8. A pair of photodiodes converts each of a pair of optical signals output from the interferometer into an electric signal. A photodetector circuit converts differential current obtained by a pair of the photodiodes into voltage and outputs as a detection signal. A first decision circuit outputs one-bit information based on the voltage of the detection signal. A second decision circuit outputs one-bit information based on a squared value of the voltage of the detection signal.

Abstract: Techniques and devices that use polarization rotation and optical interferometry to provide optical spectrum analysis of an optical signal.

Abstract: Methods and systems for controlling power in a communications network are provided. In one embodiment, a method comprises reading a power level of a communication link; and, driving an attenuation control signal based on the power level of the communication link. When the power level is greater than or equal to a minimum supported power level, driving an attenuation control signal further comprises constraining the attenuation control signal to a calibrated range of a characteristic curve. When one or both of the power level is less than the minimum supported power level and a bit error rate is greater than a maximum error threshold, driving an attenuation control signal further comprises generating an attenuation control signal outside the calibrated range of the characteristic curve.

Abstract: A calculation processing unit controls temperature of a Peltier device based on a slope of a waveform obtained by subtracting a waveform of a B-arm monitoring signal from a waveform of an A-arm monitoring signal and a value obtained by subtracting a value B of the B-arm monitoring signal from a value A of the A-arm monitoring signal. Similarly, the calculation processing unit controls a phase of the A-arm and a phase of the B-arm. An A-arm side micro-controller controls temperature of an A-arm side heater 22 based on the value of the A-arm monitoring signal, and controls the phase of the A-arm. A B-arm side micro-controller controls temperature of a B-arm side heater based on the value B of the B-arm monitoring signal, and controls the phase of the B-arm.

Abstract: Branches are grouped into a group 1 including first and second branches, and a group 2 including third and fourth branches. The signal after being passed through a dual pin photodiode in one branch included in the group 1 and being at the earlier stage of a CDR circuit is obtained. Also, from the later stage of the CDR circuit in the other branch in the group 1 is obtained. The obtained signals are passed through low pass filters, and an average value over a plurality of symbols is obtained. The signal from the earlier stage of the CDR circuit is multiplied by the signal from the later stage, and they are averaged. The obtained value reflects the phase difference of the two delay interferometers in the group 1. The group 2 is monitored by using the same method.

Abstract: An optical receiver has a monolithically integrated electrical and optical circuit that includes a substrate with a planar surface. Along the planar surface, the monolithically integrated electrical and optical circuit has an optical hybrid, one or more variable optical attenuators, and photodetectors. The optical hybrid is connected to receive light beams, to interfere light of said received light beams with a plurality of relative phases and to output said interfered light via optical outputs thereof. Each of the one or more variable optical attenuators connects between a corresponding one of the optical outputs and a corresponding one of the photodetectors.

Abstract: The present invention relates to a numerous user laser communications optical system. Numerous optical signals comprising a number of channels are simultaneously received and demultiplexed (and/or multiplexed and transmitted) at a numerous access communication device. The numerous access communication device may comprise multiple stages that each include a multiple order waveplate and a polarizing beam splitter. The multiple order waveplate is configured so that it retards a first electrical field component of signals corresponding to certain channels in a frequency grid in an integer multiple of wavelengths with respect to a second electrical field component, and retards a first electrical field component of signals corresponding to other channels in the frequency grid in an integer multiple of wavelengths plus one-half a wavelength with respect to a second electrical field component. Separation can then be performed on the basis of the resulting opposite polarization.

Abstract: A demodulator comprises an input splitter, optical device sets, and couplers. The input splitter splits an input signal comprising symbols to yield a number of signals. A first optical device set directs a signal of along a first path. A second optical device set directs another signal along a second path to yield a delayed signal. At least a portion of the second path is in free space. A path length difference between the first path and the second path introduces a symbol delay between the first signal and the second signal. A coupler receives a portion of the signal and a portion of the delayed signal to generate interference, where the interference indicates a phase shift between a phase corresponding to a symbol and a successive phase corresponding to a successive symbol.

Abstract: An optical burst mode receiver comprises a photo-detector receiving an optical signal for conversion to a current signal, a transimpedance amplifier receiving and converting the current signal into first and second transmit signals, a limiting amplifier comprising first and second input terminals and an output terminal generating a data signal, and a control circuit coupled to the first and second transmit signals to verify that if the optical signal is valid. The control circuit is further coupled to the first and second input terminals of the limiting amplifier. When the optical signal is valid, the control circuit provides the first and second input terminals with the first and second transmit signals respectively to generate the data signal. When the optical signal is invalid, the control circuit provides the first and second input terminals with distinct voltage levels to maintain the data signal at a steady level.

Abstract: A method of data compression and transmission include splitting a wave function representative of an input data set into an arbitrarily oriented elliptical polarization state and a comparator wave function state, the comparator wave function state being transmitted to a detector. A quantum Fourier transform is performed on the arbitrarily oriented elliptical polarization state to yield a quantum computational product. A quantum Hadamard transform is performed on the quantum computational product to yield one of two possible quantum particle outputs. The input data set is reconstructed based upon the coincident arrival of the comparator wave function state and one of the two quantum particle outputs. A method is performed on either a quantum computer or a digital computer. An optical bench with appropriate electronics is particularly well suited to function as a quantum computer for the compression and transmission of data corresponding to sound.

Abstract: An illumination light receiver includes: a wavelength separation mechanism separating visible light containing optical signal data distributed among wavelengths corresponding to three primary colors into the wavelengths corresponding to the three primary colors; a dispersion restraining mechanism restraining dispersion of light outputted from the wavelength separation mechanism; and a light receiving portion illuminated, separately for each of the separated wavelengths corresponding to the three primary colors, by the light outputted from the dispersion restraining mechanism, the light receiving portion converting the optical signal data into and extracting an electrical signal.

Abstract: A method for transmitting a signal and a fiber optic system comprising: a frequency modulated source; an optical transmission fiber positioned to receive the output of the frequency modulated source; an optical filter positioned to receive the output of the optical transmission fiber; and an optical receiver positioned to receive the output of the optical filter; characterized in that: an optical spectrum reshaper is positioned between the frequency modulated source and the optical transmission fiber; and wherein the optical filter is a narrow band pass filter relative to the bit rate of the transmitted signal; and further wherein the frequency excursion of the frequency modulated source is between 20% and 120% of the bit rate frequency.

Abstract: The invention relates to a receiver circuit having an optical receiving device, a plurality of amplifiers that are connected to the receiving device, and circuit means or a control circuit for individually activating and deactivating the individual amplifiers. In this case, the amplifiers each differ from one another in at least one parameter such as gain, and only one amplifier is activated at a given point in time, while the other amplifiers are deactivated. The invention makes it possible to match the receiver circuit to widely varying transmission rates.

Abstract: The present invention relates generally to an optical CDMA transmission system and method employing differential optical encoding and bipolar decoding. Differential encoding and bipolar decoding may be performed at the bit level, wherein differential phase encoding and decoding occurs on an entire composite signal. Differential encoding and bipolar decoding may also be performed at the chip level, wherein differential phase encoding and decoding occurs on individual spectral components of a given signal.

Abstract: An interconnect system has an optical transmitter mounted on a first circuit board and an optical receiver mounted on a second circuit board. The optical receiver can be nominally aligned to receive an optical signal through free space from the optical transmitter. Further, the optical receiver includes one or more light detectors, and an optical antenna coupled to direct incident light into the one or more light detectors.

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 modulating the beam portions phase and coupling ratio of directional couplers in the optical beam combiner tuned to maximize the final output power. A portion of the output beam is used for the power detection and forming a feedback signal for the phases and coupling ratios adjustment. The data is recovered from the received optical beam using coherent detection.