Abstract: An optical interrogation system and a method are described herein that enable the interrogation of one or more biosensors which can be located within the wells of a microplate. In one embodiment, the optical interrogation system has a tunable laser, N-fiber launches, N-lenses and N-detectors that are set-up to interrogate N-biosensors. In another embodiment, the optical interrogation system has a tunable laser, N-fiber launches, N+1 lenses and N-detectors that are set-up to interrogate N-biosensors.

Abstract: A system and method for superheterodyne detection in accordance with the invention. The system comprises a first conversion unit for performing a first heterodyne operation on an optical input signal to generate an electrical IF signal. A second conversion unit is electrically or optically coupled to the first conversion unit. The second conversion unit performs a second heterodyne operation to generate an electrical output signal suitable for signal processing.

Abstract: A method and device are presented for use in determining a rate of rotation of an object. The device comprises a light guide comprising an arrangement of a plurality of coupled optical resonators arranged along a curvilinear optical path. This allows for determining a change in at least one of the light phase and frequency affected by the light propagation through the curvilinear path during the device rotation, said change being indicative of the rotation rate of the light guide.

Abstract: An image data set acquired by an optical coherence tomography (OCT) system is corrected for effects due to motion of the sample. A first set of A-scans is acquired within a time short enough to avoid any significant motion of the sample. A second more extensive set of A-scans is acquired over an overlapping region on the sample. Significant sample motion may occur during acquisition of the second set. A-scans from the first set are matched with A-scans from the second set, based on similarity between the longitudinal optical scattering profiles they contain. Such matched pairs of A-scans are likely to correspond to the same region in the sample. Comparison of the OCT scanner coordinates that produced each A-scan in a matching pair, in conjunction with any shift in the longitudinal scattering profiles between the pair of A-scans, reveals the displacement of the sample between acquisition of the first and second A-scans in the pair.

Abstract: A method and system for providing fast interrogation of a signal received from a fiber optic sensor array using a low drive voltage, by modulating the array signal with a phase generated carrier optical signal having an odd harmonic modulation frequency, sending it to an interferometric system, and demodulating the array signal using a demodulation algorithm that is independent of the phase offset. A detector using direct detection method can be used to determine the signal's phase information. The odd harmonic modulation method allows the selection of a desirable odd harmonic PGC frequency with low drive voltage while providing similar performance of the usual PGC frequency that requires a higher drive voltage.

Abstract: A direct detection method and apparatus for a fiber optic acoustic sensor array systems using an in-line Michelson sensor TDM array and an interferometric section having two acousto-optic modulators that produce optical pulses that are frequency shifted with respect to each other. Direct detection is accomplished according to the equation: I(t)=A+B cos [?1??2+2?(f1?f2)t], with the phase shift difference ?1??2 between two paths containing the acoustic phase information and the frequency f1?f2 being the difference between the RF frequencies for the two acousto-optic modulators.

Abstract: An optical fiber extends down hole from an OFDR. A first set of sensors with a centrally-located reference reflector is disposed over a first fiber length, and a second set of sensors with a centrally-located reference reflector is disposed over a second fiber length. The sensors of the first and second sensing lengths are positioned at slightly offset positions from the reference reflectors so as to interleave the reflected signals. Additional sensing lengths may be similarly interleaved. The system is used by sending an optical signal along the optical fiber, detecting a reflected optical signal, separating the optical signal into component signals, and extrapolating a well condition therefrom. Another method includes creating a low frequency signal component in a reflected optical signal by placing at least one sensor beyond a Nyquist sampling distance limit, detecting the low frequency signal component, and extrapolating a well condition therefrom.

Abstract: An optical resonant modulator includes an optical ring resonator and an optical loop that is coupled to the optical ring resonator by two couplers. The optical ring resonator can have a hybrid design in which the ring resonator is formed on an electro-optically passive material and the optical loop is formed on an electro-optically active material. An amplification section can be inserted between the electro-optically passive and the electro-optically active sections. In analog applications, an optical resonator includes a Mach Zehnder interferometer section having an input and an output, with a feedback path coupling the output to the input. Applications of the optical modulator of the invention, and a method for modulating an optical signal also are disclosed.

Abstract: A hydrogen sensor, useful for trace hydrogen gas detection. The sensor involves providing a gas sample, generating modulated optical excitation sources, bringing the optical excitation source to the side of a metalized thin pyroelectric film, and detecting via a lock-in amplifier circuit the coherent differential signal resulting from thermoreflectance and thermoabsorptance changes in the film when exposed to hydrogen gas.

Abstract: Provided are optical switches applicable to various safety apparatuses which can control an operation of a circuit by detecting a switching signal such as pathogens and toxic substances, and safety apparatuses using the optical switches. The optical switch comprises an optical irradiation unit to irradiate light; an optical interference unit which can interact with a switching signal, interferes with light irradiated from the optical irradiation unit and radiates it as interference light, and can vary the wavelength of the interference light after interaction with the switching signal; and a switching unit which is provided in the path of the interference light, detects a wavelength change of the interference light, and conducts one of activating and deactivating a circuit. The safety appatatus comprises the optical switch and a hazard evasive apparatus activating unit which activates a hazard evasive apparatus using the optical switch.

Abstract: A logical element including an optical junction coupled to at least two optical inlets and to at least one optical outlet. Incoming light beams of coherent monochromatic light beams and the same uniform frequency are applied to the optical inlets, and their super-positioning is provided as an outgoing light beam(s) via the optical outlet to another logical element or to a light intensity gauge. The light intensity gauge measures light intensity in specific zone(s) of an interference pattern created by the outgoing light beam, dependent on phase shift difference between the components of the incoming light beams, and the measured intensity is correlated with intensity ranges predetermined to conjugate to logical integer values, such as Boolean or other integer numeric values. A multiplicity of logical elements can be installed to provide an optical processor. Parallel use of the same logical element is provided by the simultaneous application of sets of light beams.

Abstract: Sensor arrays utilizing standard 1×2 couplers reduce the differences in the returned optical power levels by appropriate selection of the coupling ratios. Preferred embodiments are described that comprise 6 distribution fiber lines and 16 return fiber lines. One embodiment includes 16 sensor groups in which each sensor group has a dedicated return line. In another embodiment, 8 sensor groups are configured so that no two adjacent sensors have either a common distribution fiber line or a common return fiber line.

Abstract: A sensor array employs a parameter to induce a time-varying phase angle ? on an optical signal that comprises a phase generated carrier. The phase angle ? is calculated through employment of only four samples, where all the four samples are based on the optical signal.

Abstract: A method for selecting a cell from each member of a tri-cell photodetector array used to detect optical signals output from a multichannel sensor array to indicate interference between two optical signals of unknown polarization incident upon the tri-cell photodetector array comprises selecting a cell in each tri-cell photodetector and collecting a selected number of samples of the signal output for each cell. Each sample has an in-phase AC component I and a quadrature AC component Q. An amplitude sum signal E=I*I+Q*Q is calculated for a predetermined number of samples in the selected number of samples of the signal output for each cell. The signal output of cell in each tri-cell photodetector having the largest value of the amplitude sum signal is selected for further processing.

Abstract: In a device (100) for continuously varying the extinction ratio, ER, a laser diode (102) is connected to a first end of a PZ fiber (108). At a second end, the PZ fiber is connected to a connector (110). At the other end of the connector a PM fiber (106) is connected. The two fibers meet in the connector, which means that opposite end facets of the fibers are located at a very close distance of each other. A rotation is produced by a rotator (104), mechanically coupled to the connector. The device can be used for: selecting a desired ER of the PM fiber; achieving high accuracy of angular alignment between the principal axes of two PM fibers (106, 506); evaluating the quality of angular alignment of a splice between two PM fibers made by a splicer; and setting the adjustment/calibration of a PM fiber.

Abstract: An integrated optical chip device for molecular diagnostics comprising a tunable laser cavity sensor chip using heterodyned detection at the juncture of a sensor laser and a reference laser, and including a microfluid chip to which the sensor chip is flip-chip bonded to form a sample chamber that includes exposed evanescent field material of the tunable laser cavity to which fluid to be diagnosed is directed.

Abstract: A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>103 pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.

Abstract: A portion of at least one fiber is moved into an exterior annulus of a well between a tubular structure in the well and the wall of the borehole of the well such that the portion is placed to conduct a signal responsive to at least one parameter in the exterior annulus. One particular implementation uses fiber optic cable with a cementing process whereby flowing cementing fluid pulls the portion of the cable into the exterior annulus.

Abstract: A measurement apparatus for an optical signal under test includes a closed-loop optical path, an optical mixer in the closed-loop optical path and a photodetector. The optical signal under test and sampling light having a wavelength different from that of the optical signal under test are circulated in the closed-loop optical path. Sum/difference frequency light is generated every time the sampling light passes through the optical mixer. The sum/difference frequency light is detected by the photodetector, which provides a signal representative of the waveform of the optical signal under test.

Abstract: An optical system for detecting and coupling light to optical devices, and a method for aligning and calibrating the system. The system includes positioning stages and fiber sensors. The fiber sensors are used to detect the positions of calibration pieces and other sensors in a variety of configurations. From these detected positions, any misalignment of the sensors or positioning stages may be calculated and corrected for. The fiber sensors calibrate the system.

Abstract: Disclosed is a fiber optic sensor system for sensing strain of the structure by using a wavelength swept fiber laser as a light source and using a fiber Bragg grating sensor as a fiber optic sensor, comprising: a reference fiber Bragg grating sensor, a fiber Bragg grating sensor array being branched from the reference fiber Bragg grating sensor through a coupler; a strain rate measuring coordinate signal-outputting means adapted to output an optical signal having a certain wavelength, an optical detector being connected to the coupler from which the fiber Bragg grating sensor group and the strain measuring coordinate signal-outputting means are branched for detecting output signals generated from the strain measuring coordinate signal-outputting means.

Abstract: An optical sensor diagnostic system utilizing a tunable Vertical Cavity Surface Emitting Laser (VCSEL) that incorporates an integrated MEMS tuning mechanism provides variable wavelength light into an optical fiber with improved wavelength scanning speed and greater simplicity of construction. Sensors, such as Bragg gratings, are disposed along the fiber in the light path. Each sensor reflects or transmits light exhibiting a characteristic amplitude feature with respect to wavelength, the wavelength position of which is affected by an environmental stimulus imposed thereon. The power of the reflected light is converted to an electrical signal by a simple detector and monitored by circuitry that detects changes in reflected power and provides output signals indicative of the environmental stimulus for each sensor.

Abstract: A method and system for aligning optical fibers includes aperturing the optical beams from the optical fibers at two points along a path. Photodetectors are placed on the apertures and the positions of the tips of the optical fibers are controlled using actuators to center the optical beams within the apertures.

Abstract: An interferometry system including: an interferometer which during operation directs a measurement beam along a measurement path contacting a measurement object and combines at least a portion of the measurement beam with another beam to form an overlapping pair of exit beams, the interferometer including a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the measurement beam, the measurement beam contacting the beam steering element; a control circuit which during operation causes the positioning system to reorient the beam steering element in response to a change in at least one of angular orientation and position of the measurement object; a photodetector; and an optical fiber coupling an output beam derived from the overlapping pair of exit beams from the interferometer to the photodetector.

Abstract: A method of two interferometric configurations to measure bending of an extended element. The measurement arm of each configuration is a long optical fiber. A first interferometric configuration has a segment of its measurement arm attached to one side of the element. The second interferometric configuration has a segment of its measurement arm attached to one side of the element and another segment of its measurement arm attached to an opposing side of the element. The two configurations are used to obtain two sets of interference fringe measurement values. If one set is subtracted from the other, the result is intensity differential values that indicate only the effects of bending and not of temperature or pressure. Variations of the method can be used for irregularly shaped elements.

Abstract: An apparatus for performing high speed scanning of an optical delay and its application for performing optical interferometry, ranging, and imaging, including cross sectional imaging using optical coherence tomography, is disclosed. The apparatus achieves optical delay scanning by using diffractive optical elements in conjunction with imaging optics. In one embodiment a diffraction grating disperses an optical beam into different spectral frequency or wavelength components which are collimated by a lens. A mirror is placed one focal length away from the lens and the alteration of the grating groove density, the grating input angle, the grating output angle, and/or the mirror tilt produce a change in optical group and phase delay. This apparatus permits the optical group and phase delay to be scanned by scanning the angle of the mirror. In other embodiments, this device permits optical delay scanning without the use of moving parts.

Abstract: A method and apparatus for compensating for systematic error in a wavelength measuring device that provides values for the wavelengths reflected from one or more optical fibers in which fiber Bragg gratings (FBGs) serve as sensors. A high-precision temperature sensing and measuring circuit is used to measure the temperature of a reference FBG that also provides light at some wavelength to the wavelength measuring device. The wavelength reflected by the reference FBG changes with temperature in a way that is known. The (value of) the wavelength being reflected from the reference FBG is then provided to a dynamic compensator, which also receives the wavelengths of light reflected from the sensor FBGs, and the dynamic compensator adjusts the wavelengths of the sensor FBGs using a correction based on the correction required to adjust the value of the wavelength of the reference FBG as measured by the wavelength measuring device.

Abstract: This invention provides a method and an apparatus for fiber optic tomographic analysis and imaging of fluids. This invention includes a method for providing information on downhole fluid flowing in a hydrocarbon well, utilizing at least one downhole tomograph chamber (10). Light is introduced into the tomograph chamber (10) by an optical fiber bundle (24), and portions of the light are collected in other optical fiber bundles (32, 34). The collected portions of light are conveyed through the optical fiber bundles (32, 34) to a surface system (14), where the light is detected to produce signals proportional to the portions of light to provide information on optical properties of downhole fluid flowing in the well. This invention allows the generation of two or three dimensional images of multiple phase flow in the wellbore and allows determination of production parameters of multiple zones on an individual zone basis.

Abstract: An apparatus for performing high speed scanning of an optical delay and its application for performing optical interferometry, ranging, and imaging, including cross sectional imaging using optical coherence tomography, is disclosed. The apparatus achieves optical delay scanning by using diffractive optical elements in conjunction with imaging optics. In one embodiment a diffraction grating disperses an optical beam into different spectral frequency or wavelength components which are collimated by a lens. A mirror is placed one focal length away from the lens and the alteration of the grating groove density, the grating input angle, the grating output angle, and/or the mirror tilt produce a change in optical group and phase delay. This apparatus permits the optical group and phase delay to be scanned by scanning the angle of the mirror. In other embodiments, this device permits optical delay scanning without the use of moving parts.

Abstract: A structure for incorporating fiber optic acoustic sensor in a seismic array includes means for supporting the sensor in a spiral around a central strength member in a manner to isolate shear waves from the sensor. In another aspect, an axially oriented sensor in a seismic array comprises a pressure sensitive optical fiber wound in a spiral around the axis, the fiber having a plurality of optical Bragg gratings and a plurality of channels. The preferred structure may include four tubes spiraling around the strength member. One of the tubes encloses an optical fiber sensor which is maintained in an extended orientation by fluid flow through the tube. Another of the tubes serves as a return path for fluid through the sensor tube. The other tubes enclose high speed and low speed data conductors, respectively. The sensor fiber may also be wound in a spiral around a compliant core in a manner to satisfy Poisson's Ratio such that strain on the compliant core does not alter the tension of the sensor fiber.

Abstract: A pressure measuring instrument that utilizes the change of the refractive index of a gas as a function of pressure and the coherent nature of a laser light to determine the barometric pressure within an environment. As the gas pressure in a closed environment varies, the index of refraction of the gas changes. The amount of change is a function of the gas pressure. By illuminating the gas with a laser light source, causing the wavelength of the light to change, pressure can be quantified by measuring the shift in fringes (alternating light and dark bands produced when coherent light is mixed) in an interferometer.