Abstract: In part, the disclosure relates to a constellation shaping system that includes a plurality of encoders, wherein one or more of the plurality of encoders is associated with a priority level according to a configuration, wherein a pulse is allocated to a time slot, using an encoder based on priority level of the encoder.

Abstract: Aspects of the present disclosure describe systems, methods, and structures for high speed frequency hopping distributed acoustic sensing using an acousto-optic modulated (AOM), gated re-circulating loop and a frequency shifted receiver local oscillator. Using the re-circulating loop controlled by the AOM to generate frequency-hopping pulse(s) increases DAS acoustic bandwidth overcomes infirmities exhibited in the art that generate multiple frequency patterns that are not suitable for long-distance DAS. Additionally, by employing frequency shifted local oscillator (LO) with asymmetric in band detection, bandwidth requirements are reduced by one half.

Abstract: The present disclosure includes systems and methods for testing bundles of fiber optic fibers, such as fiber optic trunk cables, for correct polarity of connections at each end of the bundle of fibers while preventing the fiber optic fibers from contacting any other components during testing. The systems include a processor, a plurality of signal generators interfaced with a plurality of signal generator ports, a sensor interfaced with a sensor input port, a first selector switch, and a display, the processor operable to stimulate the plurality of signal generators one at a time in a first sequence to produce a signal, the first sequence based on a position of the first selector switch, the processor further operable to cause the display to display an output of the sensor.

Abstract: A format for modified IRIB-G time code, with added message fields while preserving pulse width coding rule of the standard IRIG-B time code, having a time interval field for carrying time interval between the local time signal and a received time signal, and a user-defined or padded field for carrying user-defined time and/or control messages. An encoding and a decoding methods and devices for high-precision time transfer, where the modified IRIG-B time code carries more messages, and enabling transmission of timing messages and testing messages of two-way time comparison via a single message channel at the same time, which reduces fluctuation due to encoding and decoding manipulation and correlation with working frequencies via exact synchronization between the on-times of the output encoded time code and the transmitted time signal, and between the on-times of the output decoded time signal and the input time code, and improves precision of time transfer.

Abstract: Disclosed herein are a visible light communication method and apparatus. The visible light communication method includes determining a dimming level variable to perform minute dimming control, selecting an upper dimming symbol and a lower dimming symbol, which belong to Variable Pulse Position Modulation (VPPM) symbols, based on the dimming level variable, determining at least one of the number of upper dimming symbols to be sent and the number of lower dimming symbols to be sent based on the dimming level variable, and generating a transmission sequence corresponding to the dimming level variable by combining the upper dimming symbols and the lower dimming symbols based on the number of symbols to be sent.

Abstract: Systems and methods are disclosed to provide an upstream rate between 1 Gbps and 10 Gbps in a cost effective manner in a 10 GEPON. In an embodiment, an optical network unit (ONU) transmitter includes a burst transceiver and a physical layer (PHY) including a high performance digital to analog converter (DAC), a pulse amplitude modulation (PAM) module configured to encode end user data using a modulation scheme having more than two levels, and a laser. The ONU transmitter transmits the encoded end user data to an optical line terminal (OLT) receiver, which demodulates the data using a PAM demodulator and sends it to a service provider.

Abstract: A Pseudo-Return-to-Zero modulator is provided with a narrow pulse clock generator, a modulator driver, and an optical modulator. The narrow pulse clock generator generates a narrow pulse clock of order n, where one of levels occupies half a symbol period and the other level occupies (n?1) plus half a symbol period, n being equal to or more than two. The modulator driver generates an electrical signal in response to binary data and the narrow pulse clock. The optical modulator modulates an optical carrier in response to the electrical signal so that the modulated optical carrier is in a PRZ(n) format.

Abstract: It is aimed to provide a phase modulation apparatus that realizes high-precision phase modulation in high-speed phase modulation of dual optical pulses. A phase modulator 105 included in the phase modulation apparatus, when a dual optical pulse with a time difference composed of a signal optical pulse SP and a reference optical pulse RP passes therethrough, phase-modulates this dual optical pulse in proportion to an applied voltage of an electrical pulse. As a result, a phase-modulated SP? and a phase-modulated RP? are output. A modulation signal generator 106 outputs an electrical pulse of a predetermined bias at an input timing of a trigger signal, according to an input of a four-valued data signal, for example. The modulation signal generator 106 outputs, for one input of the trigger signal, a dual electrical pulse having a time difference and having opposite polarities.

Abstract: A high data rate optical signal is inverse multiplexed into a multitude of lower-rate tributaries, each of which is coded by its unique OCDM code, and the combined coded tributaries are injected into a common phase scrambler. Coherent summation of these optically encoded tributaries pass through a shared phase or phase and frequency scrambler before exiting the secure location. The setting of the scrambler acts as the key. The authorized recipient with the correct key retrieves the ones and zeros of the several decoded signals.

Abstract: An optical modulator includes a light input/output unit receiving an incident optical signal which has not been modulated, splitting the incident optical signal into a first optical signal and a second optical signal, and transmitting the first and second optical signals to a first path and a second path, respectively, of an optical waveguide. A phase shifter is positioned in at least one of the first and second paths and modulates a phase of at least one of the first and second optical signals, which have been received through the first and second paths, respectively, in response to an electrical signal. A phase-modulated signal is output. A reflective grating coupler reflects signals respectively received through the first and second paths back along the first and second paths respectively.

Abstract: Data security of a multi-dimensional code system is increased. An optical device is provided with a single input port; a splitter splitting an input light from the input port into a plurality of lights; a plurality of phase shifters each shifting one of the lights split by the splitter; a multi-port encoder/decoder inputting the lights whose phases are shifted by the phase shifters and generating spectral encoded codes; and a plurality of output ports outputting the spectral encoded codes generated by the multi-port encoder/decoder.

Abstract: Provided is an optical module. The optical module includes: an optical bench having a first trench of a first depth and a second trench of a second depth that is less than the first depth; a lens in the first trench of the optical bench; at least one semiconductor chip in the second trench of the optical bench; and a flexible printed circuit board covering an upper surface of the optical bench except for the first and second trenches, wherein the optical bench is a metal optical bench or a silicon optical bench.

Abstract: Various embodiments are directed to a photonic impulse generator comprising a periodically chirped photonic source a single-frequency photonic source, a photodetector, an optical coupler, and a filter. The optical coupler may be positioned to couple an output of the single-frequency photonic source to an output of the periodically chirped photonic source, resulting in a combined photonic signal. The photodetector may be positioned to receive the combined photonic signal and generate a combined electrical signal. The filter may be in electrical communication with an output of the photodetector to receive the combined electrical signal.

Abstract: An apparatus transmits data using a format where information bits intended for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through pulse position modulation (PPM) format and the rest of which are encoded through an additional modulation format on each PPM pulse. The additional modulation format for the PPM pulse may be at least one of a polarization-division-multiplexed (PDM) modulation, phase-shift keying (PSK) modulation, polarization shift keying (PolSK) modulation, amplitude modulation (AM), quadrature-amplitude modulation (QAM) modulation, or a combination thereof. In one embodiment, the additional modulation of the PPM pulses is through polarization-division-multiplexed quadrature-phase-shift keying (PDM-QPSK). The unique combined use of PDM-QPSK and PPM produces much higher receiver sensitivity than either PPM or PDM-QPSK alone.

Abstract: In a device and method for the optical transmission of data using a pulse-width-modulated LED (2), a startup phase ascertainment unit (3) for ascertaining at least one startup phase of the LED (2) as a function of a sequence of detected switching states of the LED (2) and a modulation unit (4) for modulating the data to a light signal emitted by the LED (2) during the ascertained startup phase of the LED (2) are provided, and data packets are first deleted from the data packet queue or queues after they have been successfully transmitted.

Abstract: Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream.

Abstract: In a method and an apparatus for the optical transmission of data by a pulse-width modulated light source (LED), in which a set dimming factor (N) is replaced with a cycle-dependent dimming factor (NI), the cycle-dependent dimming factor is modulated for encoding the data to be transmitted and corresponds to the set dimming factor over a time interval which is resolvable for the human eye.

Abstract: A PPM transmitter includes an optical clock generator for generating equally-spaced optical pulses with a sampling period T; an encoder for transforming an incoming waveform U(t) into a linear combination V(t) of U(t) and a delayed output V(t?kT) according to a rule V(t)=U(t)+aV(t?kT), where k is a positive integer, V(t) is voltage generated by the encoder and a is a coefficient; and an optical delay generator for delaying optical pulses generated by the optical clock generator in proportion to the voltage V(t), such that ?tn=bV(t), where b is another coefficient and where ?tn is the amount of delay imposed by the optical delay generator. The PPM transmitter functions with a PPM receiver for communicating data without the need to transmit or otherwise provide a clock signal. The PPM receiver decodes an original series of the delayed optical pulses Q(t) and a second series Q(t?ckT) delayed by ckT where c is a coefficient.

Abstract: An optical communication system and method of use are described. The system comprises an optical source adapted to receive a digitally encoded data signal comprising sequences of data at a data rate (B) and comprising two signal levels representing a first state and a second state of the data signal, the optical source being adapted to produce an optical signal substantially frequency modulated with frequency excursion ?? comprising a first instantaneous frequency (?0) associated to the first state and a second instantaneous frequency (?1) associated to the second state; an optical converter adapted to receive the substantially frequency modulated optical signal, the optical converter having an optical transfer function varying with frequency and including at least one pass band, the at least one pass band having a peak transmittance and at least a low-transmittance region.

Abstract: A system and method for transporting encrypted data having a transmitter and a receiver is provided. The transmitter generates a sequence of optical pulses, which are copied and output as identical channels. The identical channels are modulated by a plurality of modulators using data to generate a modulated data signal. Respective spectral phase encoders coupled to each of the plurality of data modulators encode respective modulated data signals using a plurality of mutually orthogonal phase codes that are individually associated with the respective spectral phase encoder. These encoded data signals are combined and code-scrambling by a spectral phase scrambler using a scramble code as an encryption key to generate an encrypted signal. A receiver reverses the encryption to extract the data.

Abstract: Provided is a multi-value optical transmitter in which a DC bias may be controlled to be stabilized so as to obtain stable optical transmission signal quality in multi-value modulation using a dual-electrode MZ modulator. The multi-value optical transmitter includes: D/A converters for performing D/A conversion on first and second modulation data which are set based on an input data series, so as to generate a first and a second multi-value signal, respectively; a dual-electrode MZ modulator including phase modulators for modulating light from a light source based on the first multi-value signal and the second multi-value signal, so as to combine optical signals from the phase modulators to output the optical multi-value signal; an optical output power monitor for detecting average power of the optical multi-value signal; and a DC bias control unit for controlling a DC bias for the dual-electrode MZ modulator, so as to maximize the average power.

Abstract: In a passive optical communication network system, an optical signal OCDM-coded is transmitted from an OLT to a first port of a circulator, which in turn transfers the signal from its second port to one end of a first SSFBG. The first SSFBG then decodes the signal of one channel to output the decoded signal from its one end to the second port of the circulator, which in turn transmits the decoded signal from its third port to an ONU. When the ONU transmits an optical signal to the third port of the circulator, the circulator transfers the signal from its fourth port to one end of a second SSFBG, which in turn encodes the signal to output the encoded signal from its one end to the fourth port of the circulator. The circulator then transmits the encoded signal from its first port to the OLT.

Abstract: A photoacoustic imaging system comprising a coded laser emitting apparatus and a photoacoustic signal receiving apparatus is provided. The coded laser emitting apparatus comprises an encoding unit, a signal generating unit and a laser light source. The encoding unit is used for generating a coded signal. The signal generating unit is used for generating a modulated signal according to the coded signal. The laser light source is used for generating a laser pulse having a specific coded waveform according to the modulated signal. The photoacoustic signal receiving apparatus comprises a photoacoustic signal receiving unit and a decoding unit. The photoacoustic signal receiving unit is used for receiving a photoacoustic signal generated by an object having received the laser pulse and converts the photoacoustic signal into an electrical signal.

Abstract: An optical code division multiplexing signal generator provided with an optical pulse light source, a first encoder to an Nth encoder, a first optical modulator to an Nth optical modulator, and a first optical circulator to an Nth optical circulator. The first optical circulator inputs an input optical pulse train to a first encoder, and inputs a first encoded optical pulse train output by Bragg reflection from the first encoder to the first optical modulator. The kth optical circulator inputs an input (k?1)th optical pulse train which has passed through the (k?1)th encoder to a kth encoder, and inputs a kth encoded optical pulse train output by Bragg reflection from the kth encoder to the kth optical modulator. Herein k takes all integers from 2 to N, and N is a positive integer of 2 or more.

Abstract: An optical communication system and method of use are described. The system comprises an optical source adapted to receive a digitally encoded data signal comprising sequences of data at a data rate (B) and comprising two signal levels representing a first state and a second state of the data signal, the optical source being adapted to produce an optical signal substantially frequency modulated with frequency excursion ?? comprising a first instantaneous frequency (?0) associated to the first state and a second instantaneous frequency (?1) associated to the second state; an optical converter adapted to receive the substantially frequency modulated optical signal, the optical converter having an optical transfer function varying with frequency and including at least one pass band, the at least one pass band having a peak transmittance and at least a low-transmittance region.

Abstract: An optical code communication system comprises an optical transmitter, an optical receiver, and an optical transmission line. The optical receiver has an optical mixing decoder for mixing a coded light and a local light, dividing the mixed light into an object optical frequency and a non-object optical frequency, and outputting the lights and a detection adder-subtractor filter for detecting the object optical frequency and the non-object optical frequency, filtering the intermediate frequency signals, subtracting one of the intermediate frequency signal from the other, and outputting the resultant intermediate frequency signal. The coded light and the local light are coherent with each other between the optical frequency chips constituting the coded light when detected.

Abstract: The present invention is directed toward systems for conducting laser range and enabling optical communication between a plurality of entities and to the application of such systems in a secure covert combat identification system. In one embodiment, the present invention uses a novel laser system that generates high pulse rates, as required for optical communications, while concurrently generating sufficiently high power levels, as required by laser range finding operations. One application of the present invention is in enabling secure covert communications between a plurality of parties. Another application of the present invention is in tracking and identifying the movement of objects.

Abstract: An optical pulse time spreading device includes S optical pulse time spreading elements that spread input optical pulses into trains of (N×j) chip pulses, where j is an integer greater than zero, S is an integer greater than one, and N is an integer equal to or greater than S. In the chip pulse trains output by the n-th optical pulse time spreading element (n=1, 2, . . . , S), the light in successive chip pulses is shifted in phase by successive integer multiples of the quantity 2?{a+(n?1)/N}, where a is an arbitrary constant (0?a<1). In an optical code-division multiplexing system, this optical pulse time spreading device produces an autocorrelation wave with a high energy and a high signal-to-noise ratio.

Abstract: A phase control arrangement has a structure in which a Superstructured fiber Bragg Grating (SSFBG) 40 has fifteen unit Fiber Bragg Gratings (FBGs) arranged in series in a waveguide direction. The SSFBG 40 is fixed to the core of an optical fiber 36 that includes a core 34 and cladding 32. The difference ?n between the maximum and minimum of the effective refractive index of the optical fiber is 6.2×10?5. The phase difference of Bragg reflected light from two unit diffraction gratings that adjoin one another from front to back and provide equal code values is given by 2?M+(?/2), where M is an integer. Further, the phase difference of the Bragg reflected light from two unit diffraction gratings that adjoin one another from front to back and provide different code values is given by 2?M+(2N+1)?+(?/2) where M and N are integers.

Abstract: A modulator arrangement for modulating an optical signal using a differential quadrature phase shift key for use in an optical wavelength division multiplex (WDM) optical communications system comprising a laser for producing an optical signal of a selected wavelength, which signal is split by a splitter (4), each part of said split signal being applied to a respective phase modulator (6, 8). The phase modulators (6, 8) are adapted to modulate the phase of the signal in dependence on a respective drive voltage and the phase of the output of at least one modulator is shiftable. The split signals are recombined by an optical recombiner (12) to form an optical phase shift key output. The arrangement further comprises a phase modulator (20) adapted to chirp the optical phase shift key output.

Abstract: The invention provides an optical transmitter comprising a differential encoder having first and second outputs, the first and second outputs being of opposite polarity to one another, a first RZ converter connected to the first output of the differential encoder and a second RZ converter connected to the second output of the differential encoder, and a dual electrode Mach Zehnder modulator to which an unmodulated coherent light source is coupled, wherein the output of the first RZ converter is connected to a first electrode of the Mach Zehnder modulator and the output of the second RZ converter is connected to a second electrode of the Mach Zehnder modulator. The invention provides improved signal integrity as compared with existing RZ-DPSK solution through the use of high quality RZ drivers. Furthermore, the invention gives rise to controllable RZ pulse edge chirping, providing rapid pulse compression or broadening through a dispersive fibre length.

Abstract: An arrangement for generating beat notes with a relatively high signal-to-noise ratio (SNR) utilizes a pulsed laser source coupled into a section of post-processed highly-nonlinear optical fiber (HNLF) to generate a frequency comb having one or more regions of enhanced spectral power. A second laser signal source is overlapped with the frequency comb to form one or more “beat notes” at difference frequencies(y) between the second source and the continuum comb. By virtue of the post-processing, areas of spectral enhancement are formed along the comb, and are positioned to interact with the second laser signal to generate optical beat notes. The second laser signal may be from an external source (forming beat notes from a signal “outside” of the comb), or may be a frequency-multiplied version of the generated supercontinuum (forming beat notes from a signal “within” the comb).

Abstract: A method and system for storing and transmitting data using variable pulse characteristics to represent ASCII or UNICODE characters, of the value of a string of data using a number base higher than 2. Pulse characteristics are modified to correspond to different data values. Pulse characteristics can include pulse durations, pulse spacings, pulse amplitudes, pulse phases, pulse polarities, pulse shapes and/or other pulse characteristics.

Abstract: The present invention is an optical pulse time spreading device comprising a plurality of optical pulse time spreaders that output an input optical pulse as a series of chip pulses stream that are sequentially arranged time-spread on a time axis in accordance with optical phase code. Each of the optical pulse time spreaders comprises phase control means that supplies a phase difference between adjacent chip pulses. Identification parameters are introduced to realize channel discrimination by changing the phase difference conditions supplied between adjacent chip pulses for each of the phase control means. The phase control means have a structure in which an SSFBG is fixed to the core of the optical fiber, for example. The SSFBG has unit FBGs that are arranged in series in the waveguide direction of the core. The code values of the optical phase code established for the phase control means correspond each one-on-one with each of the unit FBGs.

Abstract: A system and method for transporting encrypted data having a transmitter and a receiver is provided. The transmitter generates a sequence of optical pulses, which are copied and output as identical channels. The identical channels are modulated by a plurality of modulators using data to generate a modulated data signal. Respective spectral phase encoders coupled to each of the plurality of data modulators encode respective modulated data signals using a plurality of mutually orthogonal phase codes that are individually associated with the respective spectral phase encoder. These encoded data signals are combined and code-scrambling by a spectral phase scrambler t using a scramble code as an encryption key to generate an encrypted signal. A receiver reverses the encryption to extract the data.

Abstract: The present invention is an optical multiplex communication system in which an optical wavelength division channel and an optical code division channel can coexist, wherein a WDM channel section 86 has a wavelength demultiplexer 36 and WDM channels W1 to W4. An optical pulse string 83-3 is demultiplexed by the wavelength demultiplexer 36, and for channel W1, an optical pulse 37 with wavelength ?1 is input to an intensity modulator 114 and converted into an optical pulse signal of channel W1, and is output as a wavelength division optical pulse signal 115, where transmission information of channel W1 is reflected.

Abstract: An interference-rejection coding method for an optical wireless communication system and such an optical wireless communication system are provided. The coding method uses delay modulation, block code techniques and filtering to reduce the low frequency interference from light sources. A plurality of codewords from the block codes are reserved for performing digital data recovery. The invention removes the need of analog clock data recovery circuit, and does not require complex hardware for realization. Therefore, it can be applied to a wide range of applications, such as optical WLAN, data transmission of medical facilities, wireless communication in the aircraft, encrypted data transmission network, and low-priced transmission interfaces.

Abstract: Before being incident to a nonlinear medium, a short pulse is intensity-modulated with a bit string pattern, and then made incident. When the pulse light corresponding to a bit value ‘0’ is incident to the nonlinear medium, the pulse light is intensity-modulated so that the spectral width thereof is not spread to a predetermined spectral region due to the nonlinear phenomena, thereby producing a light state of being not output from an optical demultiplexer. Meanwhile, when the pulse light corresponding to a bit value ‘1’ is incident to the nonlinear medium, the pulse light is intensity-modulated so that the spectral width thereof is spread to the predetermined spectral region due to the nonlinear phenomena, thereby producing a light state of being output from the optical demultiplexer.

Abstract: The present invention is directed toward systems for conducting laser range and enabling optical communication between a plurality of entities and to the application of such systems in a secure covert combat identification system. In one embodiment, the present invention uses a novel laser system that generates high pulse rates, as required for optical communications, while concurrently generating sufficiently high power levels, as required by laser range finding operations. One application of the present invention is in enabling secure covert communications between a plurality of parties. Another application of the present invention is in tracking and identifying the movement of objects.

Abstract: One aspect of the present invention can include a communication system that includes at least one optical fiber, a hue encoder, and a hue decoder. The optical fiber can convey digitally encoded information that has been encoded in an optical carrier wave. The hue encoder can digitally encode a set of bits of information in a single pulse of light having a characteristic hue, wherein values for the two or more bits are determined from the characteristic hue of the pulse. The hue decoder can digitally decode a set of two or more bits of information from a single pulse of light having a characteristic hue, wherein values for the set of bits are determined from the characteristic hue of the pulse.

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: System and method for transmitting and receiving encoded signals over a network along with one or more additional signals transported within a spectral gap created by the coded signals.

Abstract: A method and system is disclosed for making timing alignment for a data transmission system, the method comprising providing a reference clock signal with a first frequency to a multiplexer through a phase shifter, generating a multiplexed signal with a second frequency by the multiplexer, wherein the second frequency follows the first frequency and is higher than the first frequency by a predetermined proportion, sending the multiplexed signal to a modulator, and phase shifting the reference clock signal by the phase shifter before the reference clock signal is provided to the multiplexer, wherein a timing of the multiplexed signal at the second frequency level can be adjusted by adjusting a timing of the reference clock signal at the lower first frequency level.

Abstract: Systems and methods are described for pulse communications using precision timing. A method includes digitally pulse coding a data stream; and modulating a carrier signal using the digitally pulse coded data stream.

Abstract: An optical transmission system which provides bandwidth restricted optical signal comprises an input terminal (10) for accepting an electrical binary signal, an amplifier (12) for amplifying said electrical binary signal to the level requested for operating an electrical-optical converter (16) such as a Mach Zehnder light modulator, a bandwidth restriction means (14) which is for instance a low pass filter for restricting bandwidth of said electrical binary signal, and an electrical-optical conversion means (16) such as a Mach Zehnder light modulator for converting electrical signal to optical signal. Because of the location of the low pass filter (14) between an output of the amplifier (12) and the Mach Zehnder light modulator (16), the amplifier (12) may operate in saturation region to provide high level output signal enough for operating the Mach Zehnder light modulator, and a signal shaped by the low pass filter (14) is applied to the Mach Zehnder light modulator (16) with excellent waveform.

Abstract: A miniature waveform modulator is provided to modulate an infrared laser. The miniature waveform modulator outputs a pulse train having different and specified pulse widths, with the pulse train used to modulate the laser. In one embodiment, the pulse train extends over a significant period of time without resorting to generating short pulse trains and combining them. The subject architecture permits the miniature waveform modulator to be compact and implementable on an electronic circuit card. It is significant that the pulse train is generated without software intervention by automatically copying a timing table to a buffer that is automatically read out to a pulse generator. If the buffer size is smaller than that required by the timing table, slices or segments of the timing table are sequentially read out or copied to the buffer, with the next timing table segment transferred to the buffer upon read out of a prior segment.

Abstract: A system for generating a return-to-zero differentially-phase-shift-keyed (RZ-DPSK) optical signal comprising: a driver comprising an N-level digital multilevel transformer (DMT) configured to receive a two level digital electrical signal representing 1s and 0s and output a N-level electrical signal, wherein N>2; an FM source configured to receive the N-level electrical signal output by the driver and generate an optical frequency modulated signal; and an optical spectrum reshaper (OSR) configured to receive the optical frequency modulated signal output by the FM source and generate the desired RZ-DPSK optical signal.

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: The extended range of optical data communication is enabled through the use of intermediary relay stations spaced fairly far apart. IRDA communicatiOn, as is well known, uses very short duration optical pulses to send data up to 1 Mbit/sec; this has the concomitant effect of minimizing LED duty cycle and preventing excessive heating. The invention uses a number of integrated pulses to represent a single bit instead of utilizing a one-to-one correspondence between pulses and bits. Processing software causes the transmitter to “stutter” or repetitively emanate the identical pulse representing a bit of information. Sufficient photons are thereby gathered at a receiver to reach a predetermined threshold. A tradeoff of the data transmission frequency in this invention is that as signal intensity drops by a factor of 100 when distance increases by a factor of 10 yielding a distance/intensity ratio of 1/10.

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.