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 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: 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: A burst detector featuring a dynamic threshold that is calculated according to the detection efficiency while operating in a noisy environment. In one embodiment, signals from various directions are multiplied by appropriate weights, wherein the weights are a function of the FAR, the throughput, and/or various modem indications.

Abstract: The invention provides, according to its various embodiments, a method for secure communication that involves encoding and transmitting an optical communications signal that is encoded based on a multi-dimensional encoding technique. The multi-dimensional encoding technique includes multiple security layers and varies multiple physical characteristics of a communications signal. The multi-dimensional encoding technique may include at least one or more of encoding a phase of an optical communications signal, encoding a polarization of an optical communications signal, and encoding a frequency of an optical communications signal, or any combination thereof. According to embodiments of the invention, the encoding and/or any decoding of the optical communications signal may be carried out using one or more of an optical phase shift coding, a polarization multiplexing, and a multi-wavelength control. Multi-dimensional encoding and decoding keys are provided.

Abstract: A method and corresponding device for joint signal detection and direction of arrival estimation, based on the ability to identify both the existence and direction of arrival of a required signal featuring known characteristics, before it is forwarded to a modem. Optionally, after identifying the existence and direction of arrival of a required signal, the direction of arrival is entered into a beamformer featuring high resolution, for obtaining the signal coming from the required direction of arrival. The calculated signal is then entered into a modem.

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: 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: 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: An optical device includes, a first Mach-Zehnder modulator that produces a first output, and a second Mach-Zehnder modulator which produces a second output. A splitter couples the first and second Mach-Zehnder modulators. A combiner combines the first and second outputs. A phase shifter is coupled to the first and second Mach-Zehnder modulators. The first Mach-Zehnder modulator, second Mach-Zehnder modulator, splitter, combiner and the phase shifter are each formed as part of a single chip made of electro-optical material. Such two similar optical device integrated together with polarization combiner provide a two-polarization performance.

Abstract: An optical system provides information about tangential vibration components of a surface at remote location. The optical system includes a light source assembly that emits first and second beams, each having one or more wavelengths and one or two polarizations. The first and second beams are directed to the interrogated surface. A detector system is positioned to detect a third beam formed by at least a portion of the first and second beams being reflected from the interrogated surface. The first, second and third beams having incident and reflection angles relative to the interrogated surface that do not lay in a same plane. The detector system positioned remotely from the interrogated surface, and providing information on a phase change in the third beam relative to the first and second beam. The phase change is indicative of at least one surface vibration vector component of the interrogated surface. The detector system is a 90 degree optical hybrid balanced detector with four photodiodes.

Abstract: The present invention relates to a method for transmitting data. An optical pulse stream comprising a plurality of return-to-zero optical pulses is prepared by modulating a phase of light output by an optical source to thereby encode data from a data source. The light of the optical pulse stream has a wavelength. The optical pulse stream is transmitted along an optical fiber of an optical network. Optical pulse streams of the invention enhance transmission performance at least in part by reducing noise at the receiver caused by fiber non-linearities.

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: A system for optical communication forms a family of orthogonal optical codes modulated by a data stream. The orthogonal codes are formed by creating a stream of evenly spaced-apart pulses using a pulse spreader circuit and modulating the pulses in amplitude and/or phase to form a family of orthogonal optical code words, each representing a symbol. A spreader calibration circuit is used to ensure accurate timing and modulation. Each code word is further modulated by a predetermined number of data bits. The data modulation scheme splits a code word into H and V components, and further processes the components prior to modulation with data, followed by recombining with a polarization beam combiner. The data-modulated code word is then sent, along with others to receiver. The received signal is detected and demodulated with the help of a symbol synchronization unit which establishes the beginning and end of the code words.

Abstract: A method and corresponding device for joint signal detection and direction of arrival estimation, based on the ability to identify both the existence and direction of arrival of a required signal featuring known characteristics, before it is forwarded to a modem. Optionally, after identifying the existence and direction of arrival of a required signal, the direction of arrival is entered into a beamformer featuring high resolution, for obtaining the signal coming from the required direction of arrival. The calculated signal is then entered into a modem.

Abstract: A system for optical communication send optical signals over a plurality of wavelength channels. Each wavelength channel comprises a number of orthogonal subchannel frequencies which are spaced apart from one another by a predetermined amount. Each of the subchannel frequencies is modulated with data from a data stream. The data modulation scheme splits a subchannel frequency code into H and V components, and further processes the components prior to modulation with data. The various data-modulated subchannels are then combined into a single channel for transmission. The received signals are detected and demodulated with the help of a symbol timing recovery module which establishes the beginning and end of each symbol. A polarization mode distortion compensation module at the receiver is used to mitigate the effects to polarization more distortion in the fiber.

Abstract: An optical system provides information about tangential vibration components of a surface at remote location. The optical system includes a light source assembly that emits first and second beams, each having one or more wavelengths and one or two polarizations. The first and second beams are directed to the interrogated surface. A detector system is positioned to detect a third beam formed by at least a portion of the first and second beams being reflected from the interrogated surface. The first, second and third beams having incident and reflection angles relative to the interrogated surface that do not lay in a same plane. The detector system positioned remotely from the interrogated surface, and providing information on a phase change in the third beam relative to the first and second beam. The phase change is indicative of at least one surface vibration vector component of the interrogated surface. The detector system is a 90 degree optical hybrid balanced detector with four photodiodes.

Abstract: The invention provides, according to its various embodiments, a method for secure communication that involves encoding and transmitting an optical communications signal that is encoded based on a multi-dimensional encoding technique. The multi-dimensional encoding technique includes multiple security layers and varies multiple physical characteristics of a communications signal. The multi-dimensional encoding technique may include at least one or more of encoding a phase of an optical communications signal, encoding a polarization of an optical communications signal, and encoding a frequency of an optical communications signal, or any combination thereof.

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: An optical device includes, a first Mach-Zehnder modulator that produces a first output, and a second Mach-Zehnder modulator which produces a second output. A splitter couples the first and second Mach-Zehnder modulators. A combiner combines the first and second outputs. A phase shifter is coupled to the first and second Mach-Zehnder modulators. The first Mach-Zehnder modulator, second Mach-Zehnder modulator, splitter, combiner and the phase shifter are each formed as part of a single chip made of electro-optical material. Such two similar optical device integrated together with polarization combiner provide a two-polarization performance.