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

Abstract: The present invention discloses a transmitter and receiver for optical communications system, which provide compensation of the optical link nonlinearity. M-PSK modulating is used for data embedding in an optical signal in each WDM channel using orthogonal frequency division multiplexing (OFDM) technique. At the receiver side electrical output signals from a coherent optical receiver are processed digitally with the link nonlinearity compensation. It is followed by the signal conversion into frequency domain and information recovery from each subcarrier of the OFDM signal. At the transmitter side an OFDM encoder provides a correction of I and Q components of a M-PSK modulator driving signal to compensate the link nonlinearity prior to sending the optical signal to the receiver.

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

Abstract: The present invention discloses a transmitter and receiver for optical communications system, which provide compensation of the optical link nonlinearity. M-PSK modulating is used for data embedding in an optical signal in each WDM channel using orthogonal frequency division multiplexing (OFDM) technique. At the receiver side electrical output signals from a coherent optical receiver are processed digitally with the link nonlinearity compensation. It is followed by the signal conversion into frequency domain and information recovery from each subcarrier of the OFDM signal. At the transmitter side an OFDM encoder provides a correction of I and Q components of a M-PSK modulator driving signal to compensate the link nonlinearity prior to sending the optical signal to the receiver.

Abstract: A method and system for high Z substance revealing using muon detection technique is presented. Natural muon coordinate and incidence angle are measured above and below the interrogated volume. The muon deviations after passing through the interrogated volume are compared with the reference deviations obtained for the same volume in absence of high Z material. A correlation between the actual data and reference data is calculated using Kolmogorov-Smirnov test, though other approaches may apply. The correlation is used for the decision making on the presence of a nuclear substance inside the volume.

Abstract: The invention provides a system and method for secure communication that involves encoding and transmitting an optical communications signal that is encoded based on a multi-dimensional encoding technique. This technique may include at least one or more of encoding a phase, a polarization, and a frequency of the signal. Light encoding is independent from its modulation with data. The data is modulated using any format; in the preferred embodiment the QPSK format is implemented. The encoded and modulated light is transmitted through free space or via a fiber optic network to a receiver, where the information is decoded. A coherent detection based on 90-degrees or 120-degrees optical hybrid is used to decode and recover the data from the received signal. Because the encoding of the transmitted light varies according to a specific pattern or sequence, one without knowledge of the transmission encoding sequence is prevented from decoding the transmitted information.

Abstract: A method and system for nuclear substance revealing using muon detection technique is presented. In some aspects, naturally occurred muons are selected from the flow of charged particles. Muon coordinate and incidence angle measured above and below the interrogated volume can be used for the decision making on the presence of nuclear substance inside the volume. The system is adapted for performing measurements on moving objects such as moving trucks. A combination of the nuclear substance detection system with an explosive sensing system is presented.

Abstract: A method and system for nuclear substance revealing using muon detection technique is presented. In some aspects, naturally occurred muons are selected from the flow of charged particles. Muon coordinate and incidence angle measured above and below the interrogated volume can be used for the decision making on the presence of nuclear substance inside the volume. The system is adapted for performing measurements on moving objects such as moving trucks. A combination of the nuclear substance detection system with an explosive sensing system is presented.

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.

Abstract: A photo-thermal, interferometric spectroscopy system is disclosed that provides information about a chemical, such as explosives and the like, at a remote location. It may be used for solid residue detection on a surface. The system includes a novel light detector system with a matrix of optical elements focusing portions of a received light beam on input waveguides of an optical combiner. The combiner adjusts the phases of the received beam portions and combines them together to maximize the intensity of an output beam. The output beam is detected by a detector, and information about at least one of, absorption spectrum and concentration of the chemical is recovered. In the preferred embodiment the detector is a coherent detector based on 90-degrees optical hybrid.

Abstract: A method and system for high Z material revealing using muon detection technique is presented. The system measures muons' coordinates, velocities, incidence angles and leaving angles. Two series of detectors: one above and one below the interrogated volume are used. A muon trajectory deviation from an expected trajectory is used for the decision making on the presence of high Z material inside the volume. The muon velocity is measured using either a ring Cerenkov counter, a transition radiation detector or/and a threshold Cerenkov counter. The expected trajectory is calculated basing on known particle velocity.

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

Abstract: The present invention discloses a transmitter and receiver for optical communications system, which provide compensation of the optical link nonlinearity. M-PSK modulating is used for data embedding in an optical signal in each WDM channel using orthogonal frequency division multiplexing (OFDM) technique. At the receiver side electrical output signals from a coherent optical receiver are processed digitally with the link nonlinearity compensation. It is followed by the signal conversion into frequency domain and information recovery from each subcarrier of the OFDM signal. At the transmitter side an OFDM encoder provides a correction of I and Q components of a M-PSK modulator driving signal to compensate the link nonlinearity prior to sending the optical signal to the receiver.

Abstract: An optical beam synthesizer formed on a single chip is provided. It allows M-PSK modulation for both beam polarizations. The synthesizer comprises an optical pulse shaper and two M-PSK modulators for each polarization. A single-chip-integrated analyzer is provided to receive a modulated data. Analyzer comprises a pulse shaper operating as an optical sampler and a pair of 90-degrees optical hybrids for each polarization. Each optical hybrids mix incoming portions of the modulated beams with portions of the local oscillator beams. Both the synthesizer and the analyzer include a set of mirrors located on the back and front surfaces of the chips to create compact designs. The output beams from the analyzer are detected by a set of balanced photodiodes, and the data is recovered. It is another object of the invention to provide a communication system for data transmission having the synthesizer and the analyzer.

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

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

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

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

Abstract: A photo-thermal interferometric spectroscopy system is disclosed that provides information about a chemical at a remote location. A first light source assembly is included that emits a first beam. The first beam has one or more wavelengths that interact with the chemical and change a refractive index of the chemical. A second laser produces a second beam. The second beam interacts with the chemical resulting in a third beam with a phase change that corresponds with the change of the refractive index of the chemical. A detector system is positioned remote from the chemical to receive at least a portion of the third beam. An adaptive optics system at least partially compensates the light beam degradation caused by atmospheric turbulence.

Abstract: The present invention provides an integrated device and a method of its fabrication and use. Two parts of the device each having an electronic circuit are aligned adjacent to each other with an accuracy of at least 1 micron. An alignment system includes two parts: a first part integrated with the first electronic circuit of the integrated device on the first substrate and a second part integrated with the second electronic circuit of the integrated device on the second substrate. The second part of alignment system includes at least one photodiode. The maximal value of the photodiode current indicates the best alignment of two parts of the integrated device. In one embodiment the integrated device is a coherent optical detector for high speed optical communications and chemical sensing. In another embodiment the integrated optical device is a coherent optical detector operating in two polarization states of light.