Abstract: An optical communication system is provided. In one embodiment, a source creates a multiplicity of photon pairs, with each photon pair comprising a first photon and a second photon. The first photon is sent to a transmitter, and either remains in the transmitter or is transmitted by the transmitter to a receiver. The second photon is sent to the receiver. Data is decoded by determining a polarization direction and a time of detection of any photon pairs detected at the receiver.

Abstract: An open-path/free-space optical communication system using reflected light has modulated optical or laser sources and provides communication between the modulated source and a detector in an obstructed line-of-sight relationship. The system detects backscattered light impinging on a target illuminated by the source of light. Barrier objects positioned in a line-of-sight path between the source and detector are circumvented and a first device that provides the modulation signal for the source controls a remote second device.

Abstract: An embodiment of the present invention provides an apparatus, comprising a radio frequency identification transceiver adapted for self jammer suppression. The transceiver may further comprise a phase shifter and variable attenuator/variable amplifier adjusted to minimize the power injected into a receive chain by the self jammer. In an embodiment of the present invention the present transceiver may further comprise at least one RF peak power detector to determine the power injected into the receive chain.

Abstract: A photon emitter including a photon generator configured to generate photons having a first polarization state or a second polarization state, the first polarization state being orthogonal to the second polarization state; and a time delay device which delays photons having the second polarization state with respect to those having the first polarization state.

Abstract: An optical network monitoring system and method provide for optical network diverting or further legal intercept, operational and/or other monitoring of general or specific transmission information that may be transmitted via a network optical branch. In one embodiment, a splitter within a diverter assembly diverts a portion of a received transmission signal (strength) to an optical receiver or re-transmitter, and outputs a further portion of the signal via a diverter assembly output or further via a re-transmitter or booster. In another embodiment, the splitter is generally matched to the receiver. A further embodiment provides for transferring the diverted portion to a monitoring assembly with which the diverting assembly may be matched, disposed or otherwise integrated, and which may provide for configuring the diverting assembly.

Abstract: A method for creating a logic state for teleporting quantum information using a single photon is described. The method includes receiving a photon with an initial polarization and causing a first semiconductor crystal to have a first spin orientation. The photon interacts with the first semiconductor crystal for producing a resulting polarization dependent upon the first spin orientation. Causing the photon to interact with the first semiconductor crystal generates a maximally entangled state.

Abstract: The subject invention pertains to a method and apparatus for multiplexing in optical fiber communications. The subject invention relates to a method and apparatus for spatial domain modulation in optical wavelengths. In a specific embodiment, the subject invention relates to a spatial domain multiplexer (SDM) for use with an optical fiber. Preferably, the input channels coupled into the fiber optic cable include collimated laser beams. The techniques of the subject invention can be utilized with single mode and multi mode waveguide structures, for example, single mode and multi mode optical fibers. The subject invention is applicable to step index optical fiber and to graded index optical fiber. Applications of the subject technology can include secure data links, for example, which can modulate data such that if the data is intercepted, the data cannot be interpreted. The subject methods and apparatus can also be used in conjunction with other multiplexing techniques such as time-domain multiplexing.

Abstract: A method and apparatus for securing an optical communication link includes the step of identifying a profile of the link by measuring, at the transmitter, optical back-reflections from optical pulses forwarded to a receiver. The profile is stored at the transmitter. Periodically during operation, such as during key exchange, more optical pulses are forwarded to the receiver, and the back reflections are collected as periodic profiles. The periodic profiles are compared against the stored profiles. Eavesdroppers, such as those who cut the fiber, tap the fiber, or implement a man in the middle attack, may be easily identified because the losses caused by their interference with the fiber will be evident in the periodic profiles.

Abstract: The invention provides systems and methods enabling high fidelity quantum communication over long communication channels even in the presence of significant loss in the channels. The invention involves laser manipulation of quantum correlated atomic ensembles using linear optic components (110, 120), optical sources of low intensity pulses (10), interferers in the form of beam splitters (150), and single-photon detectors (180, 190) requiring only moderate efficiencies. The invention provides fault-tolerant entanglement generation and connection using a sequence of steps that each provide built-in entanglement purification and that are each resilient to realistic noise levels. The invention relies upon collective rather single particle excitations in atomic ensembles and results in communication efficiency scaling polynomially with the total length of the communication channel.

Abstract: A method and apparatus for securing an optical communication link includes the step of identifying a profile of the link by measuring, at the transmitter, optical back-reflections from optical pulses forwarded to a receiver. The profile is stored at the transmitter. Periodically during operation, such as during key exchange, more optical pulses are forwarded to the receiver, and the back reflections are collected as periodic profiles. The periodic profiles are compared against the stored profiles. Eavesdroppers, such as those who cut the fiber, tap the fiber, or implement a man in the middle attack, may be easily identified because the losses caused by their interference with the fiber will be evident in the periodic profiles.

Abstract: A device connects to a male network connector of a network conduit, and connects to a female network connector of the network conduit. The female network connector is capable of communicating with the male network connector. The device also measures outputs of the male network connector and the female network connector.

Abstract: A method for protecting a data entry device from eavesdropping includes masking a signature of entry resulting from entry of data by a user of the data entry device so as to reduce the detectability of the signature by eavesdropping. The signature may include a temperature differential in the data entry device from data entry by the user and the masking may include controlling the external temperature of the data entry device to reduce temperature differentials left in the data entry device by the user. Alternatively, the signature may include sound waves emitted from the data entry device and the masking may include masking sound waves emitted from the data entry device to reduce the detectability of the sound waves. A system may also be employed for protecting data entry to a data entry device from eavesdropping.

Abstract: A Quantum Dense Coding System. The system includes a source, a transmitter and a receiver. The source is capable of down-converting a pump photon into a signal photon and an idler photon and outputting probability amplitudes, the signal photon and the idler photon, wherein the signal photon and the idler photon have an equal probability of outputting to a transmission channel and a reception channel. The transmitter is capable of receiving probability amplitudes, signal photons and idler photons from the transmission channel; and selectively changing vertical and horizontal phases of probability amplitudes of signal photons and idler photons; and outputting probability amplitudes, signal photons and idler photons. The receiver is capable of receiving probability amplitudes, signal photons and idler photons from the reception channel and the transmitter; and identifying vertical and horizontal phase changes created by the transmitter. A method for the system is also described.

Abstract: Apparatus and methods for high fidelity quantum communication over long communication channels even in the presence of significant loss in the channels are disclosed. The invention employs laser manipulation of quantum correlated atomic ensembles using linear optic components, optical sources of low intensity pulses, beam splitters, and single-photon detectors requiring only moderate efficiencies. The invention provides fault-tolerant entanglement generation and connection, using a sequence of steps that each provide built-in entanglement purification and that are each resilient to the realistic noise. The invention relies upon collective excitation in atomic ensembles rather than single particle excitations in atomic ensembles so that communication efficiency scales polynomially with the total length of a communication channel.

Abstract: An optical binary code transmission system comprising a sender comprising: means for generating a light beam; phase-shifter means; attenuator means whereby the intensity of the lateral modes is sufficiently low for there to exist at the most only one photon in the lateral modes. The phase-shifter means of the sender impose a phase-shift that is chosen randomly to be equal either to 0 or to ?/2 for a first bit value or either to ? or to 3?/2 for a second bit value, and the receiver comprising means for detecting the presence of a photon in the first lateral mode and means for detecting the presence of a photon in the second lateral mode, a first bit value being detected if the presence of a photon is detected in the first lateral mode and a second bit value being detected if the presence of a photon is detected in the second lateral mode.

Abstract: The invention provides systems and methods enabling high fidelity quantum communication over long communication channels even in the presence of significant loss in the channels comprising laser manipulation of quantum correlated atomic ensembles using linear optic components (110, 120), optical sources of low intensity pulses (10), beam splitters (150), single-photon detectors (180, 190) requiring only moderate efficiencies. The invention provides fault-tolerant entanglement generation, connection, using a sequence of steps that each provide built-in entanglement purification and are each resilient to the realistic noise. The invention relies upon collective rather single particle excitations in atomic ensembles and result in communication efficiency scaling polynomially with the total length of a communication channel.

Abstract: The specification describes optical fibers that are constructed to prevent theft of optical signals. One construction is designed to block access of the core of the fiber to the “writing” radiation necessary to form a grating tap. In this embodiment the optical fiber cladding is provided with a highly absorbing UV layer. In a variation of this embodiment, one or more additional optical paths are provided in the optical fiber to accommodate monitoring signals. The added optical paths allow monitoring signals to be transmitted in the optical fiber, separate from the information signal, to signal an attempt to breach the outer coating or the cladding of the optical fiber. A second case of intrusion is addressed by increasing the sensitivity of the optical fiber to microbending loss to the extent that bends in the fiber cause such high attenuation of the signal that the bends do not go undetected at the receiving station.

Abstract: Apparatus and techniques for detecting malfunctions, anomalies and attacks upon optical devices of a transparent all-optical network, including amplified links and optical nodes, of the network. A portion of an input signal of the optical device and a portion of an output signal from the optical device are coupled to an optical processing unit and a an optical to electrical signal converter. The electrical output signal of the converter is coupled to an electronic processing unit which generates a difference signal which is a function of the input and output signal portions for comparison to a predetermined set of parameters. The result of the comparison is an alarm signal indicative of the occurrence of a malfunction. Also described is an optical comparator capable of generating the difference signal which is indicative of perturbations in the optical device.

Abstract: Systems and methods for actively monitoring and managing the integrity of an optical fiber communications link. The optical fiber link integrity is monitored to guard against intrusions and other security breaches. In one embodiment, a local and a remote active monitoring system are coupled by four fiber paths that provide primary and back-up transmit and receive paths between communication equipment. In one embodiment, a security light signal is transmitted using a secondary wavelength that differs from the wavelength used to transmit a user data light signal and travels in an opposite direction relative to the user data light signal. An active monitoring system monitors both administrative information contained within the security light signal and the intensity of the security light signal to manage the integrity of the fiber optic link. Methods are provided to characterize events impacting the fiber optic link integrity.

Abstract: A multiplex optical communication system transmitting a multiplex optical signal between terminal equipments each including converters producing optical signals combined to the multiplex optical signal, through repeater equipment including an optical amplifier, under controlling the amplifier so that when a converter is added or removed, a time constant of the amplifier is equal to a time constant of the added or removed converter, or the amplifier produces output under constant output level control before adding or removing the converter and after the amplifier produces final output and constant gain control during the added or removed converter increases or decreases output. The time constant control is performed to the amplifier by making the amplifier repeat start and stop of increasing or decreasing output step by step in accordance with prescribed objective values corresponding to half way output of the optical amplifier.

Abstract: This invention proposes a method for enabling segment protection, whereby one or more hops in the lightpath are protected by either a dedicated or shared wavelength. This provides a more cost effective solution for the service provider such that they only need to configure protection, and therefore deploy equipment, to those sensitive portions of the network rather than dedicating wavelengths and equipment for protection end-to-end for a lightpath. Further, allowing protecting wavelengths to be shared for protection, gives further flexibility and therefore, savings, to the service provider. To utilize lightpath segment protection and sharing the protection between multiple lightpaths requires the new mesh networking capabilities of the network elements and new network management tools to configure, and monitor these protected lightpaths.