Abstract: Using a general-purpose cost-advantageous blue-light-excited-type white light emitting diode (LED), destruction of devices is prevented and visible light data communication is performed at a sufficient transmission rate. The blue-light-excited-type white LED is driven based on a driving current signal generated based on transmission data. While a visible light signal is outputted to a receiver, a multi-tone driving current signal is generated by a rising pulse and a falling pulse to a rising edge and a falling edge of the transmission data, respectively. Each of pulse widths of the rising pulse and the falling pulse is the same as a unit interval of the transmission data.

Abstract: Return To Zero (RZ) shaping is performed for a first I/Q modulator whose output corresponds to a first polarization component using a first two digital-to-analog convertors (DACs), each of which is sampled at approximately twice a modulation symbol rate or more and has an output with a first interleaving order that interleaves one of a first pair of intended drive signal patterns and zeros. RZ shaping is also performed for a second I/Q modulator whose output corresponds to a second polarization component using a second two DACs, each sampled at approximately twice the modulation symbol rate or more and having a second interleaving order that interleaves zeros and one of a second pair of intended drive signal patterns, the second interleaving order opposite the first interleaving order. The first polarization and the second polarization may be combined, thereby forming an Interleaved Return To Zero (IRZ) Polarization Division Multiplexed (PDM) signal.

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: An optical transmitter comprises: first and second sets of optical in-phase and quadrature modulators; an integrable tunable laser assembly; a first polarization beam splitter that is configured to divide the continuous-waveform optical signal into a x-polarized tributary and a y-polarized tributary, each of the x-polarized tributary and the y-polarized tributary is modulated by one of the first and second sets of optical in-phase and quadrature modulators in accordance with the two respective input signals; a second polarization beam splitter that is configured to combine the modulated x-polarized tributary and the modulated y-polarized tributary into one optical signal; and an optical modulator that is configured to modulate the combined optical signal using a driving voltage, wherein the driving voltage has a bias point that is reduced by a predefined offset from a predefined reference voltage level.

Abstract: Lamps having light emitting diodes configured for data transmission require the high-frequency circuit of higher power. In order to simplify the required electronics, the light emitting diodes are divided into groups and the groups are modulated differently. Due to the multilevel modulation, the symbol rate can be reduced with the data rate remaining the same, thus reducing the switching rate and the circuitry complexity.

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: In a first embodiment of the present invention, a method is provided comprising: receiving a selection of a desired brightness level of a light source; receiving a piece of data to be transmitted via visible light communication using the light source; selecting a duty cycle, described by an encoding scheme, based on the desired brightness level; encoding the data using the encoding scheme, wherein the encoding includes identifying a code corresponding to both the piece of data and the selected duty cycle; and transmitting the identified code via visible light communication using the light source.

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: Adaptive power setting techniques for optical transceivers are provided. Optical signals are received at a first optical transceiver device that are transmitted from a second optical transceiver device. A receive power of the optical signals received at the first optical transceiver device from the second optical transceiver device is determined. A characteristic of optical signals transmitted by the first optical transceiver device to the second optical transceiver device is modulated to indicate to the second optical transceiver device a disparity of the receive power with respect to a target receive power level at the first optical transceiver device. Conversely, the first optical transceiver device adjusts a power level of optical signals transmitted by the first optical transceiver device to the second optical transceiver device based on a characteristic of the optical signals received at the first optical transceiver device.

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: According to an embodiment, a semiconductor device includes an analog/digital conversion unit, a pulse width modulation unit outputting a transmission signal, the transmission signal being a pulse pattern corresponding to a digital signal output from the analog/digital conversion unit, a reference signal generation unit generating a reference signal, the reference signal being a fixed pulse pattern. The device includes a first control unit selecting one of the transmission signal and the reference signal, a light emitting element drive unit outputting a drive current based on the transmission signal or the reference signal, a light emitting element driven by the light emitting element drive unit. The device includes an optical receiving unit converting the optical signal into a voltage signal, and a demodulation unit demodulating the voltage signal into a digital signal based on the transmission signal or the reference 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: An optical link power management scheme takes the best advantage of a dynamic connection environment, where ports may be connected and disconnected at any time, and where data flows may start and stop as needed by the applications using the high speed data links. Power consumption is optimized, eye safety standards are met, and robust connection detection is preserved.

Abstract: An LD driver to generate an asymmetrical driving current with a relatively faster falling edge and an optical transmitter having the LD driver are disclosed. The LD driver includes a primary driver and the sub-driver connected in parallel to the primary driver. The primary driver converts the input signal or the delayed signal delayed from the input signal into the primary current. The sub-driver generates a symmetrical current tracing the input or the delayed signal, and an asymmetrical current formed by the OR operation between the input and delayed signals. The driving current is formed by adding the primary current, the symmetrical current and the asymmetrical current.

Abstract: An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some being encoded through a pulse position modulation (PPM) format and some being encoded through an additional modulation format on at least one PPM pulse. A receiver detects the signal through a dual-polarization coherent receiver front-end, recovering polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on slot position of at least one PPM pulse in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one PPM pulse in the polarization components. Pilot-assisted single-carrier frequency-division equalization (PA-SC-FDE) may be used for reliable signal reception in the presence of severe PPM errors.

Abstract: In an optical data communication system transmitter, in which a laser is driven with a laser modulation signal in response to a serial data stream, the laser driver adds peaking to a bit other than the first bit following a bit transition.

Abstract: A frequency converter includes a first direct digital synthesizer that receives a signal having a predetermined frequency f_master as a clock signal and further an internal frequency setting signal, and outputs an internal signal having a frequency based on the internal frequency setting signal, and a second direct digital synthesizer that receives the internal signal as a clock signal, and further an output frequency setting signal, and outputs an output signal having a frequency f_slave (=f_master??) based on the output frequency setting signal. A difference between the predetermined frequency f_master and the frequency of the internal signal is larger than a difference between the predetermined frequency f_master and the frequency f_slave of the output signal.

Abstract: An apparatus for transmitting data for visible light communication sets up the pulse width control step of pulse width modulation (PWM) in a unit time interval, modulates each symbol of VLC source data input into a PWM signal in accordance with the pulse width control step, generates a visible light modulation signal by controlling the turn-on time or turn-off time of a plurality of light emitting diodes (LEDs) in response to the PWM signal, and transmits the visible light modulation signal.

Abstract: A system and methods are provided for converting a first temporally short and spectrally broad optical pulse into a train of spectrally narrow and distinct optical pulses. This involves receiving, on a first I/O channel, the first optical pulse associated with a plurality of wavelengths and performing wavelength division demultiplexing on the first optical pulse at an optical unit housed on an optical chip to output a plurality of second optical pulses on different ones of a plurality of second I/O channels, each of the second optical pulses associated with a unique wavelength range from the first optical pulse. This also involves receiving the second optical pulses at loop mirrors in the second I/O channels, wherein the second I/O channels are patterned as waveguides in the optical chip and reflecting, at the loop mirrors, the second optical pulses back to the optical unit.

Abstract: A method and apparatus for dimming a luminary for lighting and data transmission in visible light communications (VLC).

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 method for imaging objects through turbid media includes generating a repetitive pulsed light beam under control of a pulse shaper, propagating the light beam through turbid media, and receiving and imaging the light beam at a sensor. Propagation through turbid media causes scattering of the light, and the sensor captures scattered pulses to produce an image. The pulse shaper controls pulse width, frequency, repetition rate and chirp of the generated light pulses according to a feedback signal received from the sensor, to improve image quality. A system for imaging objects through turbid media includes a laser for generating a light beam; a pulse shaper for controlling said light beam, and a sensor, in communication with the pulse shaper, for capturing the image of said light beam through a turbid medium. Pulse width is less than 250 femtoseconds to reduce attenuation of the light beam through the turbid medium.

Abstract: Visible light data communication with a sufficient transmission speed is performed using a general-purpose and cost-advantageous blue-light-excitation-type white LED without using a blue color filter while preventing the element from being damaged. When transmission data is inputted to a driving waveform generation unit (110) in a transmitter (100), the driving waveform generation unit (110) and a multi-gray scale driving unit (120) generate a multi-gray scale driving signal, which is supplied to the blue-light-excitation-type white LED (140) and allows the blue-light-excitation-type white LED (140) to emit light. A light signal outputted from the blue-light-excitation-type white LED (140) is collected by a lens or the like, is made incident into a PD (210) in a receiver (200), and is converted to a current signal. The current signal is converted into a voltage signal in a trans-impedance amplifier (212).

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: Systems and methods for implementing and using optoelectronic gates are disclosed. One such method includes superimposing an electrical data bit onto a first optical input to produce a pair of first-stage optical outputs. The first one of the pair of first-stage optical outputs carries the electrical data bit and the second carries the complement of the electrical data bit. The method further includes comparing an electrical target bit with the electrical data bit conveyed by the first first-stage optical outputs and with the complement of the electrical data bit conveyed by the second first-stage optical outputs, to determine whether the electrical target bit and the electrical data bit are same or different.

Abstract: An arrangement for providing pulse compression at the output of an optical continuum source (advantageously used in spectral slicing applications) includes a section of higher-order mode (HOM) fiber configured to exhibit a predetermined dispersion in at least a portion of the predetermined wavelength range and an effective area greater than 40 ?m2, the dispersion of the HOM fiber selected to compensate for the dispersion introduced by the optical continuum source. The HOM fiber generates a compressed pulse output therefrom. An input mode converter is used to convert the created continuum from the fundamental mode associated with the conventional continuum sources to the higher-order mode(s) supported by the HOM fiber used to perform pulse compression. A bandpass filter is used to limit the bandwidth of the continuum signal to that associated with both the efficient conversion range of the mode converter and desired dispersion characteristic of the HOM fiber.

Abstract: The present invention refers to a method for robust multi-level encoding of optical signals. The method uses a transmitter that transforms electric signals into optical signals and a receiver capable to transform optical signals into electric signals. The transmitter is capable to generate optical pulses having at least two different durations. The amplitudes of the pulses are preferably close to each other. The transmitter is fast, and the receiver is slow such that the response time of the receiver exceeds at least the shortest of the durations of the optical pulses. Then the receiver effectively integrates the optical signal and generates the electric signal having a larger amplitude when the optical signal has a larger duration. Thus, the method converts the modulation in pulse duration into the modulation in signal amplitude. In different embodiments of the present invention, the transmitter can be realized by a light-emitting diode, superluminescent light-emitting diode, or a diode laser.

Abstract: An optical signal representing digital data is produced by an opto-electronic semiconductor device having a group of three or more opto-electronic light sources that emit optical signals in accordance with a pulse amplitude modulation (PAM) scheme. The optical signal can be transmitted through an optical fiber coupled to an assembly containing the opto-electronic semiconductor device.

Abstract: A method and apparatus for transmission of data on bandwidth limited fiber optic channels. A multilevel signaling alphabet having multiple levels of optical intensity are used to transmit signals on optical channels. In order to counteract the decrease in signal to noise ratio resulting from the use of a multilevel signaling alphabet over a bilevel signaling alphabet trellis encoding of the data to be transmitted is employed. To counteract intersymbol interference due to signaling faster than the Nyquist Rate, equalization methods such as Tomlinson-Harashima preceding and decision feedback equalization are employed.

Abstract: Provided is a photon detector that enables an APD response by a sinusoidal wave-shaped gate signal and is operable at an arbitrary drive frequency without requiring a special band removing filter.

Abstract: The present invention provides a system, apparatus and method to efficiently switch from one modulation format to another modulation format based upon a current route or path through a network topology of a network communication system. According to various embodiments of the invention, a network topology map is generated identifying one of a plurality of paths upon which a data stream is transmitted from a transmitter to a receiver within a network, the transmitter transmitting the data in a respective one of a plurality of data modulation formats. One or more characteristics related to one of the plurality of optical paths is measured and, based upon such measurement, a desired modulation format is selected. Upon a change in the network topology, the process is repeated such that the modulation format is continuously optimized with respect to the network topology.

Abstract: An optical interconnection arrangement for use in high data applications is presented that eliminates the need for extensive serialization/de-serialization (SERDES) functionality by utilizing pulse amplitude modulation (PAM) techniques to represent the data in the optical domain while utilizing a separate channel for transmitting an optical clock signal, eliminating the need for clock recovery circuitry on the receive end of the arrangement.

Abstract: A method is described for driving a light source, particularly a HID lamp (2), the method comprising the steps of: providing a commutating DC current for supplying the lamp; and varying a commutation period (T) in order to transmit data. In an embodiment, the duration of each commutation period (T) is set to be equal to one of two possible values (T1, T2) such as to encode a digital bit.

Abstract: An LD driver to generate an asymmetrical driving current with a relatively faster falling edge and an optical transmitter having the LD driver are disclosed. The LD driver includes a primary driver and the sub-driver connected in parallel to the primary driver. The primary driver converts the input signal or the delayed signal delayed from the input signal into the primary current. The sub-driver generates a symmetrical current tracing the input or the delayed signal, and an asymmetrical current formed by the OR operation between the input and delayed signals. The driving current is formed by adding the primary current, the symmetrical current and the asymmetrical current.

Abstract: Using a general-purpose cost-advantageous blue-light-excited-type white light emitting diode (LED), destruction of devices is prevented and visible light data communication is performed at a sufficient transmission rate. The blue-light-excited-type white LED is driven based on a driving current signal generated based on transmission data. While a visible light signal is outputted to a receiver, a multi-tone driving current signal is generated by a rising pulse and a falling pulse to a rising edge and a falling edge of the transmission data, respectively. Each of pulse widths of the rising pulse and the falling pulse is the same as a unit interval of the transmission data.

Abstract: It is provided an optical field transmitter comprising a light source, a DA converter and an optical field modulator. The optical field transmitter modulates an information signal into an optical field signal. The information signal includes one of multilevel signals arranged irregularly on a complex plane and multilevel signals arranged by combining mutually different numbers of phase values in at least two amplitude values. The optical field transmitter further comprises a phase pre-accumulation circuit for outputting phase pre-accumulation complex information obtained by previously accumulating a phase component of the information signal at predetermined time intervals. The DA converter converts the information signal including the output phase pre-accumulation complex information into an analog signal, and inputs the converted analog signal to the optical field modulator.

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: The device is structured to have a first electric modulation signal generator, a second electric modulation signal generator, a two-mode beat light source and an optical intensity modulator. The first electric modulation signal generator generates and outputs a first electric modulation signal. The second electric modulation signal generator generates and outputs a second electric modulation signal of a same frequency as the first electric modulation signal and to which a phase difference of ? radians is provided (? is a real number satisfying 0????). The two-mode beat light source is driven by the first electric modulation signal, and generates and outputs two-mode beat light. The two-mode beat light is inputted to the optical intensity modulator, and the optical intensity modulator generates and outputs a CS optical pulse train. Light transmittance of the optical intensity modulator is modulated by the second electric modulation signal.

Abstract: An apparatus for generating an RF signal is provided includes a driver configured to generate a timing control for two optical signals. The apparatus further includes at least one optical pulse source configured to generate the two optical signals based on the timing control. In addition, the apparatus includes a photodetector configured to receive the two optical signals as input and further configured to generate an RF signal based on the two optical signals. A method for generating an RF signal is also provided.

Abstract: A first modulation section performs low-speed digital modulation of first data. A second modulation section performs high-speed digital modulation of second data. A first light transmitting section alternately emits and quenches visible light in accordance with an output signal of the first modulation section to transmit a visible light signal which conveys the first data. A second light transmitting section changes an intensity of the infrared light in accordance with an output signal of the second modulation section to transmit an infrared light signal, which conveys the second data, in parallel with the visible light signal.

Abstract: A chirped pulse amplification (CPA) system and method is described wherein the dispersion of the system is tuned by actively tuning one or more system components, for example, using a temperature or strain gradient, or using actinic radiation. In other embodiments, an additional element, such as a modulator, is added to the CPA system to actively to tune the pulse. A pulse monitor is added to the system to measure an output pulse and provide feedback to one or more active tuning elements.

Abstract: A pulse transmission method for transmitting data by using pulse signals, each having a predetermined pulse width; defining a symbol time at least N times the predetermined pulse width, N being at least 2; defining a basic delay time calculated by dividing the predetermined pulse width by a predetermined integer; placing the pulse signals in the symbol time by delaying the pulse signals by an integral multiple of the basic delay time from start of the symbol time, the number of the pulse signals being k and 0?k?N being satisfied; and transmitting the pulse signals.

Abstract: A method and system for visible light communication (VLC) for use in a dimmable lighting environment is provided. The method includes transmitting data using light from at least one light source, a brightness of the light reduced below a maximum level. The method also includes compensating or accommodating for the reduced brightness of the light at a VLC circuitry to maintain communication. The method further includes transmitting data to at least one VLC receiver using the light from the at least one light source.

Abstract: It is an object of the present invention to provide a communications system for communication between two remote terminals, where even at very long distances between these two terminals and/or at very small signal-to-noise ratios a robust communication is possible. The invention achieves the goal set before by suggesting an inventive pulse position modulation scheme and a corresponding optical communications system. The system and method according to the invention are very well suited for communication with a satellite in deep space, for instance.

Abstract: The device is structured to have a first electric modulation signal generator, a second electric modulation signal generator, a two-mode beat light source and an optical intensity modulator. The first electric modulation signal generator generates and outputs a first electric modulation signal. The second electric modulation signal generator generates and outputs a second electric modulation signal of a same frequency as the first electric modulation signal and to which a phase difference of ? radians is provided (? is a real number satisfying 0????). The two-mode beat light source is driven by the first electric modulation signal, and generates and outputs two-mode beat light. The two-mode beat light is inputted to the optical intensity modulator, and the optical intensity modulator generates and outputs a CS optical pulse train. Light transmittance of the optical intensity modulator is modulated by the second electric modulation signal.

Abstract: An IR signaling generator and method divides the functionality of generation between software and hardware to provide a flexible way to generate IR signals, such as remote control signals. The hardware includes a clock generator for generating a carrier clock signal and a data clock signal, a buffer memory that is loaded with instructions representing an encoded data sequence; a control circuit, and a transmitter including a modulator. Each instruction contains an on/off value that is to be modulated with the data clock signal and a pulse duration value that indicates how long the on/off value is to modulate the clock signal. Using the data clock signal, the control circuit measures the amount of time the on/off value modulates the clock signal and causes the buffer to advance to the next instruction in the sequence when the measured amount of time is equal to the pulse duration value.

Abstract: A device can convert electrical signals into modulated light signals and conduct those modulated light signals between components within the device or between the device and another device through at least a portion of the housing of the device that is transparent to the light wavelength of the modulate light signals.

Abstract: The present invention relates to a method for modulation, the method comprising: receiving a data stream; forming a modulated electrical signal from the data stream by using a plurality of data signals, each of the plurality of data signals representing at least one data bit of the data stream, wherein one of the plurality of data signals is a zero signal and wherein the remainder of the plurality of data signals comprises periodic, positive non-zero subcarrier signals and/or non-periodic signals with a positive DC-level; and providing the modulated electrical signal representing the data stream. The present invention also relates to a device performing the modulation method and to a system incorporating such a device.

Abstract: A method and apparatus for transmission of data on bandwidth limited fiber optic channels. A multilevel signaling alphabet having multiple levels of optical intensity are used to transmit signals on optical channels. In order to counteract the decrease in signal to noise ratio resulting from the use of a multilevel signaling alphabet over a bilevel signaling alphabet trellis encoding of the data to be transmitted is employed. To counteract intersymbol interference due to signaling faster than the Nyquist Rate, equalization methods such as Tomlinson-Harashima precoding and decision feedback equalization are employed.