Abstract: A sweep sensor may include a signal source, a propagation medium, and a detector. By transmitting an interrogating signal from the signal source into the propagation medium, detectable disturbances along the medium can physically alter the characteristics of the medium, which may cause a measurable change in the backscattered signal at the detector. Based on the change, it may be possible to locate the geographic origins of the physical disturbances along the propagation medium, or to determine the nature of the disturbances, or both. For example, it is generally possible to estimate the approximate distance between the detector and the disturbance given the time required to obtain the backscattered signal and the velocity of the signal source in the propagation medium. Further, in some embodiments, it is possible to quantify the amount of disturbance.

Abstract: A sweep sensor may include a signal source, a propagation medium, and a detector. By transmitting an interrogating signal from the signal source into the propagation medium, detectable disturbances along the medium can physically alter the characteristics of the medium, which may cause a measureable change in the backscattered signal at the detector. Based on the change, it may be possible to locate the geographic origins of the physical disturbances along the propagation medium, or to determine the nature of the disturbances, or both. For example, it is generally possible to estimate the approximate distance between the detector and the disturbance given the time required to obtain the backscattered signal and the velocity of the signal source in the propagation medium. Further, in some embodiments, it is possible to quantify the amount of disturbance.

Abstract: A sweep sensor may include a signal source, a propagation medium, and a detector. By transmitting an interrogating signal from the signal source into the propagation medium, detectable disturbances along the medium can physically alter the characteristics of the medium, which may cause a measurable change in the backscattered signal at the detector. Based on the change, it may be possible to locate the geographic origins of the physical disturbances along the propagation medium, or to determine the nature of the disturbances, or both. For example, it is generally possible to estimate the approximate distance between the detector and the disturbance given the time required to obtain the backscattered signal and the velocity of the signal source in the propagation medium. Further, in some embodiments, it is possible to quantify the amount of disturbance.

Abstract: A disturbance, such as vibration from human activity, is located along a fiberoptic waveguide configuration (301-304) with two interferometers (801, 802) of the same or different types, such as Mach-Zehnder, Sagnac, and Michelson interferometers. Carrier signals from a source (101) are split at the interferometer inputs (201, 202) and re-combined at the outputs (701, 702) after propagating through the detection zone (401), where phase variations are induced by the disturbance (501). Phase responsive receivers (901, 902) detect phase relationships (1001, 1002) between the carrier signals over time. A processor (1101) combines the phase relationships into composite signals according to equations that differ for different interferometer configurations, with a time lag between or a ratio of the composite signals representing the location of the disturbance.

Abstract: A sweep sensor may include a signal source, a propagation medium, and a detector. By transmitting an interrogating signal from the signal source into the propagation medium, detectable disturbances along the medium can physically alter the characteristics of the medium, which may cause a measurable change in the backscattered signal at the detector. Based on the change, it may be possible to locate the geographic origins of the physical disturbances along the propagation medium, or to determine the nature of the disturbances, or both. For example, it is generally possible to estimate the approximate distance between the detector and the disturbance given the time required to obtain the backscattered signal and the velocity of the signal source in the propagation medium. Further, in some embodiments, it is possible to quantify the amount of disturbance.

Abstract: The location of a physical disturbance along an optical waveguide is determined by measuring different propagation times for the resulting phase variation to propagate to phase responsive receivers at ends of bidirectional signal paths. Each receiver can have a coupler that functions as a beam combiner and as a beam splitter inserting the opposite signal. On each receiving end, the coupler provides one or more detectors with signals from which phase related independent variable values are taken, processed and mapped to phase angles. Relative phase angle versus time is derived for each opposite signal pair and correlated at a time difference, i.e., a difference in propagation time from which the location of the disturbance is resolved. Polarization sensitive and polarization insensitive examples are discussed with various optical fiber arrangements.

Abstract: A disturbance, such as vibration from human activity, is located along a fiberoptic waveguide configuration (301-304) with two interferometers (801, 802) of the same or different types, such as Mach-Zehnder, Sagnac, and Michelson interferometers. Carrier signals from a source (101) are split at the interferometer inputs (201, 202) and re-combined at the outputs (701, 702) after propagating through the detection zone (401), where phase variations are induced by the disturbance (501). Phase responsive receivers (901, 902) detect phase relationships (1001, 1002) between the carrier signals over time. A processor (1101) combines the phase relationships into composite signals according to equations that differ for different interferometer configurations, with a time lag between or a ratio of the composite signals representing the location of the disturbance.

Abstract: The location of a physical disturbance along an optical waveguide is determined by measuring different propagation times for the resulting phase variation to propagate to phase responsive receivers at ends of bidirectional signal paths. Each receiver can have a coupler that functions as a beam combiner and as a beam splitter inserting the opposite signal. On each receiving end, the coupler provides one or more detectors with signals from which phase related independent variable values are taken, processed and mapped to phase angles. Relative phase angle versus time is derived for each opposite signal pair and correlated at a time difference, i.e., a difference in propagation time from which the location of the disturbance is resolved. Polarization sensitive and polarization insensitive examples are discussed with various optical fiber arrangements.

Abstract: The attenuation profile of an optical system, which defines the power variation as a function of wavelength is adjusted to alter the slope of its contour. The device is useful in a wavelength division modulation system to flatten the profile of an amplifier or the like that has a non uniform power variation with wavelength. The invention adjusts the slope by first providing an input light signal that has a known polarization state, e.g., processing the input into a known phase and amplitude relation between orthogonal components, such as plane polarized at a given alignment. The signal is then passed through a series of waveplates. The waveplates have different phase retardation and orientation resulting in wavelength dependent polarization change. According to an inventive aspect, by tuning the phase retardation of multiple tunable waveplates the desired wavelength dependent polarization changes over a useful wavelength range can be produced.

Abstract: Polarization effects are managed to provide differential timing information for localizing disturbances affecting two or more counter-propagating light signals on one or more optical waveguides passing through a detection zone. Activity can be localized to a point for a security perimeter. Events causing optical disturbance can be mapped to points along a straight line, a perimeter or arbitrary pattern or an array. Events cause local changes in optical properties in the optical waveguide, in particular an optical fiber. Short term local changes are distinguishable from phase changes of light travel in the waveguide by managing the polarization state of input and output beams.

Abstract: Polarization effects are managed to provide differential timing information for localizing disturbances affecting two or more counter-propagating light signals on one or more optical waveguides passing through a detection zone. Activity can be localized to a point for a security perimeter. Events causing optical disturbance can be mapped to points along a straight line, a perimeter or arbitrary pattern or an array. Events cause local changes in optical properties in the optical waveguide, in particular an optical fiber. Short term local changes are distinguishable from phase changes of light travel in the waveguide, by managing the polarization state of input and output beams, combining orthogonal polarization components and other aspects. The changes in the states of polarization of the counter-propagating light signals are determined and the temporal spacing of corresponding changes in polarization state are resolved to pinpoint the location of the event along the optical fiber.

Abstract: An intrusion detection system with a distributed sensor system coupled with a plurality of secondary sensors is disclosed. The distributed sensor is deployed over a protected zone, and detects physical disturbances caused by intrusion into the zone. A plurality of physical disturbing devices is coupled to the distributed sensor to physically disturb the distributed sensor. A plurality of secondary sensors is employed as additional sensors to volumetrically extend the sensing zone, and is coupled with physically disturbing devices. A secondary sensor sends a signal to an associated physically disturbing device upon detecting an event to be monitored, and the signal operates the physically disturbing device to produce a physical disturbance that will be detected by the distributed sensor. Location of the event is identified by analyzing the disturbance and consequently by locating the physically disturbing device and the associated secondary sensor.

Abstract: A optical polarization encoding device (16) provides wavelength dependent processing of polychromatic optical signals without prior separation into narrow wavelength bands. Embodiments of the encoding device include a wavelength dependent tunable optical switch (400, 500) and a wavelength tunable optical level controller (600). An encoded signal is processed, (e.g., rerouted or attenuated), as a function of wavelength using polarization dependent devices (18). Desired states of polarization are imparted to optical signals to either direct selected wavelengths to selected output ports (optical switch), or to adjust the level of selected channels or wavelengths (level controller). Desired polarizations are achieved simultaneously at all wavelengths contained within the incoming signal by independently varying the birefringence and/or crystallographic orientation of each variable element within the stack.

Abstract: A controller, particularly for setting a desired or randomized polarization state of an output light beam derived from an input, has more than the minimum number of controllable optical elements needed to determine the state of the output. The controller applies control input values to obtain a desired output state. The controller also selects among plural alternative sets of control values that could obtain the desired output state, so as to minimize other error conditions. The concurrent error conditions can be associated finite control range limits, for example to keep the input values near a middle of their ranges. Additional error conditions can include minimizing the incremental change in the values from one set to the next. The control is particularly useful to avoid problems associated with using finite range control elements such as liquid crystals for differential retardation or orthogonal light components, when controlling an endless or periodic parameter such as polarization.

Abstract: Polarization effects are managed to provide differential timing information for localizing disturbances affecting two or more counter-propagating light signals on one or more optical waveguides passing through a detection zone. Activity can be localized to a point for a security perimeter. Events causing optical disturbance can be mapped to points along a straight line, a perimeter or arbitrary pattern or an array. Events cause local changes in optical properties in the optical waveguide, in particular an optical fiber. Short term local changes are distinguishable from phase changes of light travel in the waveguide, by managing the polarization state of input and output beams, combining orthogonal polarization components and other aspects. The changes in the states of polarization of the counter-propagating light signals are determined and the temporal spacing of corresponding changes in polarization state are resolved to pinpoint the location of the event along the optical fiber.

Abstract: Polarization effects are managed to provide differential timing information for localizing disturbances affecting two or more counter-propagating light signals on one or more optical waveguides passing through a detection zone. Activity can be localized to a point for a security perimeter. Events causing optical disturbance can be mapped to points along a straight line, a perimeter or arbitrary pattern or an array. Events cause local changes in optical properties in the optical waveguide, in particular an optical fiber. Short term local changes are distinguishable from phase changes of light travel in the waveguide by managing the polarization state of input and output beams.

Abstract: Measurements at multiple distinct polarization measurement states are taken to define the polarization state of an input, for example to calculate a Stokes vector. High accuracy and/or capability of frequent recalibration are needed, due to the sensitivity of measurement to retardation of the input signal. A multiple measurement technique takes a set of spatially and/or temporally distinct intensity measurements through distinct waveplates and polarizers. These can be optimized as to orientation and retardation using initial choices and also using tunable elements, especially controllable birefringence elements. A device matrix defines the response of the device at each of the measurement states. The matrix can be corrected using an iterative technique to revise the device matrix, potentially by automated recalibration.

Abstract: A controller, particularly for setting a desired or randomized polarization state of an output light beam derived from an input, has more than the minimum number of controllable optical elements needed to determine the state of the output. The controller applies control input values to obtain a desired output state. The controller also selects among plural alternative sets of control values that could obtain the desired output state, so as to minimize other error conditions. The concurrent error conditions can be associated finite control range limits, for example to keep the input values near a middle of their ranges. Additional error conditions can include minimizing the incremental change in the values from one set to the next. The control is particularly useful to avoid problems associated with using finite range control elements such as liquid crystals for differential retardation or orthogonal light components, when controlling an endless or periodic parameter such as polarization.

Abstract: An interferometer optical element is provided with a birefringent material in the light path. Specifically, a Fabry-Perot optical resonance cavity is operated in a fully reflective mode and is provided with a birefringent material in a cavity between two reflectors. A first mirror, for example of about 90% reflectance and a second mirror, for example of 99% reflectance, define the cavity. The polarization effect is applied exclusively to the resonant wavelength defined by the spacing of the two reflectors. The input beam is fully reflected back in the direction of incidence. However the resonant wavelength component therein is polarized and can be discriminated, e.g., selectively diverted by a polarization beam splitter. A number of application are disclosed, including using a birefringent liquid crystal material and tuning the apparent optical path length by electrically adjusting the birefringence.

Abstract: A controllable phase plate has numerous domains that are randomized as to the orientation of their birefringence and can be used in a power limiting control to produces an electrically controllable diffraction pattern having a portion, especially the zero mode axial spot of the pattern, that is directed onto an output aperture such as a pinhole or an optical fiber end. Controlling the phase plate produces an interference peak or null (or an intermediate level) of light, coupled into the output aperture. The phase plate preferably comprises a liquid crystal with controllable birefringence. The domains have paired orthogonal orientations, which is a condition that is met in randomized domains. The paired orthogonal orientations make the device polarization insensitive. In a controllable attenuating device, collimating lenses are placed before and after the phase plate along a beam path to focus a clear interference pattern on a screen containing the output aperture.