Abstract: An improved optic system for measuring and/or controlling displacement, force, pressure, position, or chemistry is disclosed. This apparatus allows for more accurate, robust, and economical communication between the transducer (or control input element) and the reader device (or control output), allows the use of a single optic fiber and/or or a gap for the communication link, and produces substantial insensitivity to attenuation due to mechanical, chemical, thermal, and radiation effects acting on the optic fiber or open space in which the signal propagates. It is also significantly immune to interference from electromagnetic radiation, since the link can be easily produced as a non-conductor which will not propagate unwanted electrical energy or lightning, and is intrinsically safe from igniting fires or explosions. It also facilitates use on rotating machinery and remote location of the transducer by the ability to transmit the signal across a large gap or air space.

Abstract: The invention provides a method and system for measuring the length of a reflective resonator, by analyzing an electromagnetic spectrum emitted therefrom. The emitted spectrum is used for estimating a first cavity length. This estimation is thereafter improved, by first computing at least one interference number for the spectrum, adjust this value to e.g. an integer or half-integer depending on the configuration of the resonator, and thereafter re-calculating the length of the resonator using the adjusted value of the interference number. The above is an efficient way of improving the accuracy in the determination of a physical property of a resonator.

Abstract: A sensor assembly having an optical fiber, a lens in optical communication with the optical fiber, a reflective surface spaced from the lens, for reflecting light from the beam back to the lens, a partially reflective surface positioned between the reflective surface and the lens, the partially reflective surface for reflecting light from the beam back to the lens, and an alignment device for aligning the lens and reflective surface with respect to one another, such that light from the beam of light transmitted from the lens reflects from the reflective surface back to the lens. The alignment device can have a rotational component and a base component, where the rotational component rotates to align a beam of light transmitted from the lens. The rotational component can also cooperate with the base component to move axially with respect to the reflective surfaces to align the beam for optimum power.

Abstract: An apparatus for estimating a property includes a hollow core tube and an input light guide disposed at least partially within hollow core tube. The apparatus also includes a second gap disposed within the hollow core tube and separated from the input light guide by an air gap width. The second gap is formed of a first solid material and has a second gap width. The apparatus also includes a third gap disposed at least partially within the hollow core tube and being further from the input light guide than the second gap. The third gap is formed of a second solid material and has a third gap width.

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: Apparatus and methods that compensate for the thermally-induced drift of the resonance frequency of a closed-loop resonator include, in an exemplary embodiment, a waveguide-based Mach-Zehnder interferometer (MZI) and an overcoupled, waveguide-based microring resonator. The temperature-induced red-shifting ring resonance can be balanced by a spectral blueshift with temperature of the MZI. To stabilize the resonance of the ring at a given wavelength, the change in optical path lengths with temperature of the ring and the MZI should be equal and opposite. The interplay of nonlinear change in phase of ring resonator with temperature and linear change in phase of MZI with temperature, along with matching the period of this phase change, gives rise to perfect oscillation in the combined system resonance with temperature.

Abstract: A single fiber Mach-Zehnder interferometer comprises an optical fiber having a core region and a cladding surrounding the core region, and a micro-cavity having part of the cladding and the core region removed, wherein the micro-cavity is adapted to receive a light beam and separate the light beam into a first light beam that propagates through the micro-cavity in an unguided mode, and a second light beam that propagates through the core region in a guided mode.

Abstract: A method and system are disclosed for detecting the presence of a perturbation of a microresonator including the step of exciting at least first and second resonant guided optical modes of a microresonator with a light source that is in optical communication with the microresonator. The method further includes inducing a first frequency shift in the first resonant guided optical mode and a second frequency shift in the second resonant guided optical mode, wherein the second frequency shift can be zero. Another step of the method is comparing the first frequency shift and the second frequency shift.

Abstract: A free-space optical path of an optical interferometer is disposed in an environment of interest. A light beam is guided to the optical interferometer using a single-mode optical fiber. The light beam traverses the interferometer's optical path. The light beam guided to the optical path is combined with the light beam at the end of the optical path to define an output light. A temporal history of the output light is recorded.

Abstract: Apparatus, methods, and other embodiments associated with measuring environmental parameters are described herein. In one embodiment, a transducer comprises a tube, an elongated member, a first reflective surface, a second reflective surface, and an optical fiber. The tube has a first end and a second end, and the elongated member also has a first end and a second end, with the first end of the elongated member secured to the tube. The second reflective surface is secured to the second end of the elongated member, and the first reflective surface is spaced apart from the second reflective surface and secured to the second end of the tube. The optical fiber is positioned to direct light towards the first and second reflective surfaces and to collect the reflected light from these two surfaces.

Abstract: Disclosed is a microelectromechanically tunable Fabry-Perot device and method of manufacturing tunable Fabry-Perot device and method of manufacturing. The F-P device comprises a first and second substrate which has partially reflective planar surfaces, and the partially reflective planar surfaces are separated by a predetermined separation distance and aligned to provide a F-P cavity, where one or more piezoelectric members are adapted to displace the first and second substrates when an electric field is applied.

Abstract: An optical device comprising an optical device comprising a Mach-Zehnder interferometer having a first 2×2 optical coupler, a second 2×2 optical coupler, a first optical arm, and a second optical arm. The first and second arms connecting corresponding pairs of optical ports of the first and second 2×2 optical couplers. The second optical arm has a longer optical path than the first arm. The device also comprises one or more optical resonators optically coupled to the first optical arm and an optical splitter. The optical splitter is coupled to deliver a portion of an input optical signal to one port of the first 2×2 optical coupler and to deliver a remaining portion of the input optical signal to one port of the second optical coupler.

Abstract: An optical sensing system and method are disclosed. The optical sensing system includes one or more bus waveguides. A first bus waveguide includes an input port that is in optical communication with a light source. The system further includes a microresonator optically coupled to the bus waveguides and an optical scattering center configured for alteration of a strength of optical coupling between the optical scattering center and the microresonator. In addition, the system includes a detector in optical communication one of the bus waveguides or the microresonator.

Abstract: A sensor apparatus and method includes a sensor head with at least two surfaces separated by a gap. One surface is mechanically fixed, a second surface is free to move and deflections of the second surface relative to the first surface are monitored by optical interferometry. In one embodiment, an optical fiber is used to direct light from a light source to the sensor and collect light reflected by the sensor. In alternate embodiments the sensor apparatus includes integrated optical elements, free-space optics, and direct laser-diode sensing. In operation, interaction of molecules or other objects in the sample with the second surface is detected as a change in amplitude and/or phase of deflection the second surface in response to an applied driving signal. A layer of binding molecules may be immobilized on the second surface and this surface exposed to a sample.

Abstract: Apparatus for determining a parameter of a sample has an optical sensor in the form of a monofibre waveguide having a distal end coated with a film that is placed in a sample. The waveguide has an input channel connected to a radiation light source and an output channel connected to a photodiode and amplifier to receive signals representative of the interference patterns created at the interface between the film and the sample. A computer receives the signals via an analogue to digital converter for processing the information and providing a measurement of the parameter. The measurement of the parameter may be used to control a process or system.

Abstract: An optical sampler with high temporal resolution comprises a TOAD device with a loop optical path at the inlet of which is input an optical signal to be sampled and along which path is arranged a point of input of an optical control signal produced by a source and appropriately delayed by a delay line to change on command the temporal position of the TOAD transmittance window compared to the signal to be sampled. In the loop there is also a nonlinear device. The sampler includes a controller to command the delay line to move step by step the transmittance window and make it run on the signal to be sampled. The mean power transmitted at the TOAD output is measured for each window position and a derivative on the mean powers found for each window position is performed, thus finding samples representing the optical signal.

Abstract: A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.

Abstract: An optical microresonator system and a sensor are disclosed. The optical microresonator system includes an optical waveguide and an optical microresonator that is directly optically coupled to the optical waveguide. The optical microresonator further includes an optical microcavity that is core coupled to the optical microresonator but not to the optical waveguide.

Abstract: Apparatus and method for chemical and biological agent sensing. An example sensing apparatus includes a resonator having a resonance frequency. The resonator includes a coil of a photonic crystal fiber. The photonic crystal fiber has a solid region configured to guide a substantially single optical mode of light having, a cladding surrounding an exterior of the solid region, and at least one hollow core within the cladding. The cladding contains at least one hollow core. The photonic crystal fiber is configured to introduce a fluid that may contain an analyte to the hollow core. The photonic crystal fiber is configured so that the light interacts with the fluid. The resonator is configured to produce a resonance signal centered at the resonance frequency. A predetermined change in the resonance signal indicates a presence of a quantity of the analyte in the fluid.

Abstract: A device for performing polarization mode dispersion (PMD) measurements of an optical fiber is disclosed. The PMD measurement device employs a fixed analyzer method, and includes a tunable Fabry-Perot inferometer as the wavelength-selective element and an optical bandpass filter for spectrum calibration. A novel scanning algorithm, which performs multiple scans at different velocities, enables accurate PMD measurements, even of moving optical cable. The tunable Fabry-Perot interferometer is able to scan over a wide wavelength range and yet have a narrow linewidth, such that a wide range of PMD values can be measured.

Abstract: An acoustic sensor includes at least one photonic crystal structure having at least one optical resonance with a resonance frequency and a resonance lineshape. The acoustic sensor further includes a housing mechanically coupled to the at least one photonic crystal structure. At least one of the resonance frequency and the resonance lineshape is responsive to acoustic waves incident upon the housing.

Abstract: A whispering gallery mode resonator based optical sensor assembly comprises a flow channel permeable to optical energy and first and second optical waveguides adjacent to a section of the flow channel and adapted to be in first and second evanescent field couplings respectively with the section such that the section forms a whispering gallery mode resonator. The resonator is responsive to an optical signal conveyed in the first optical waveguide and communicates a second optical signal to the second optical waveguide indicative of a resonance wavelength of the whispering gallery mode resonator. A detector optically coupled to the second optical waveguide detects the output signal. A signal processor detects a shift in the output signal responsive to an analyte fluid flowing through the flow channel. The shift is indicative of the identity of at least one constituent of the analyte fluid.

Abstract: A change in mass of a microbridge in a mass sensor can be sensed by applying a time-varying amplitude modulated electrostatic force to excite the microbridge into resonance at the frequency of amplitude modulation. An optical energy is then transmitted at a wavelength close to a resonant wavelength of a Fabry-Perot microcavity, which is formed by etching a movable reflective mirror into a region of the microbridge and by etching a fixed reflective minor in a region spaced apart from the microbridge. The two mirrors are interconnected by an optical waveguide. The movable mirror and fixed mirror reflect the optical energy to a receiver, and a change in the Fabry-Perot microcavity's reflectivity is interferometrically determined. The change in reflectivity indicates a change in the microbridge's resonant frequency due to increased mass of the microbridge resulting from sorption of a target chemical by a layer of chemoselective material deposited on the microbridge.

Abstract: Apparatus, methods, and other embodiments associated with measuring environmental parameters are described herein. In one embodiment, a transducer comprises a tube, an elongated member, a first reflective surface, a second reflective surface, and an optical fiber. The tube has a first end and a second end, and the elongated member also has a first end and a second end, with the first end of the elongated member secured to the tube. The second reflective surface is secured to the second end of said elongated member, and the first reflective surface is spaced apart from the second reflective surface and secured to the second end of the tube. The optical fiber is positioned to direct light towards the first and second reflective surfaces and to collect the reflected light from these two surfaces.

Abstract: A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.

Abstract: Systems and apparatus enhance transmission of electromagnetic energy through a sub-wavelength aperture. A metal film has an input surface and an output surface and forms the sub-wavelength aperture between the input and output surfaces, a first plurality of grooves on the input surface, and a cavity around the sub-wavelength aperture. The width of the cavity determines a resonant wavelength of electromagnetic energy transmitted through the sub-wavelength aperture. The patterned metal film provides plasmon coupling of electromagnetic energy incident upon the input surface transmit electromagnetic energy through the sub-wavelength aperture.

Abstract: A differential pressure measuring system includes a light source for emitting a light, a first transducer for attenuating the intensity of the emitted light in a first range, depending on a first pressure, and providing a first light, a second transducer for attenuating the intensity of the first light in a second range, depending on a second pressure, and providing a second light, a feedback circuit for adjusting the intensity of the emitted light to maintain the intensity of the second light in the second range constant, and a measuring module for measuring a differential pressure between the first and second pressures, based on the intensities of the second light in the first and second ranges.

Abstract: Systems and methods for in-situ reflectivity degradation monitoring of optical collectors used in extreme ultraviolet (EUV) lithography processes are described. In one embodiment, a method comprises providing a semiconductor lithography tool employing an EUV source optically coupled to a collector within a vacuum chamber, the collector providing an intermediate focus area, measuring a first signal at the EUV source, measuring a second signal at the intermediate focus area, comparing the first and second signals, and monitoring a reflectivity parameter of the collector based upon the comparison. In another embodiment, a method comprises emitting a signal from a non-EUV light source optically coupled to the collector, measuring a signal reflected by the collector, and monitoring a reflectivity parameter of the collector based upon a comparison between the emitted and measured signals.

Abstract: A sensor apparatus and method includes a sensor head with at least two surfaces separated by a gap. One surface is mechanically fixed, a second surface is free to move and deflections of the second surface relative to the first surface are monitored by optical interferometry. In one embodiment, an optical fiber is used to direct light from a light source to the sensor and collect light reflected by the sensor. In alternate embodiments the sensor apparatus includes integrated optical elements, free-space optics, and direct laser-diode sensing. In operation, interaction of molecules or other objects in the sample with the second surface is detected as a change in amplitude and/or phase of deflection the second surface in response to an applied driving signal. A layer of binding molecules may be immobilized on the second surface and this surface exposed to a sample.

Abstract: A method of shifting and fixing an optical frequency of an optical resonator to a desired optical frequency, and an optical resonator made by such a method are provided. The method includes providing an optical resonator having a surface and a refractive index, and obtaining a coating composition having a predetermined concentration of a substance and having a refractive index that is substantially similar to the refractive index of the optical resonator. The coating composition inherently possesses a thickness when it is applied as a coating. The method further includes determining a coating ratio for the surface of the optical resonator and applying the coating composition onto a portion of the surface of the optical resonator based upon the determined coating ratio.

Abstract: For evaluation of a measured parameter with a measuring cell having a cavity which generates for light an optical path length difference changing corresponding to the variation of the measured parameter, the method includes: introducing light from a white light source with the aid of an optical waveguide via a coupler (3) disposed in the path of the optical waveguide into the cavity, coupling out at least a portion of the light reflected back into the optical waveguide from the cavity with the aid of the coupler and conducting this reflected light to an optical spectrometer, determining the optical spectrum of the reflected light in the spectrometer and generating a spectrometer signal, conducting the spectrometer signal to a computing unit, wherein the spectrometer signal is directly converted through the computing unit to an interferogram and from its intensity progression the location of the particular extremal amplitude value is determined and this particular location represents directly the particular va

Abstract: Apparatus and method for detecting the presence or amount or rate of binding of an analyte in a sample solution is disclosed. The apparatus includes an optical assembly having first and second reflecting surfaces separated by a distance “d” greater than 50 nm, where the first surface is formed by a layer of analyte-binding molecules, and a light source for directing a beam of light onto said first and second reflecting surface. A detector in the apparatus operates to detect a change in the thickness of the first reflecting layer resulting from binding of analyte to the analyte-binding molecules, when the assembly is placed in the solution of analyte, by detecting a shift in phase of light waves reflected from the first and second surfaces.

Abstract: Photoacoustic instruments and their methods of use are disclosed. Certain disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, a laser, an optical power detector, and a scattering detector. Further disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, an optical power detector, a plurality of laser beams, each laser beam having a different wavelength, and, optionally, a scattering detector.

Abstract: Stresses and strains on a solid surface subject to a fluid flow are dynamically measured based on a shift of optical resonances of a micro-resonator. The elastic deformation and refractive index change of a micro-resonator due to mechanical stress is exploited. With this approach, mechanical deformations in the order of a nanometer can be detected and related to shear stress.

Abstract: The present invention is a diaphragm-fiber optic sensor (DFOS), interferometric sensor. This DFOS is based on the principles of Fabry-Perot and Michelson/Mach-Zehnder. The sensor is low cost and is designed with high efficiency, reliability, and Q-point stability, fabricated using MEMS (micro mechanic-electrical system) technology, and has demonstrated excellent performance. A DFOS according to the invention includes a cavity between two surfaces: a diaphragm made of silicon or other material with a rigid body (or boss) at the center and clamped along its edge, and the endface of a single mode optic fiber. By utilizing MEMS technology, the gap width between the diaphragm and the fiber endface is made accurately, ranging from 1 micron to 10 microns.

Abstract: An assay system having a channel bounded by first and second reflective surfaces adapted to accommodate a fluid material therebetween and defining a plurality of regions in an array between those surfaces with each region defining a resonant cavity and adapted to receive a capturing material on a surface thereof whereby a source of radiation illuminates each region to provide a standing wave of radiation of within the cavity indicative of binding of said capturing agent to material under investigation, a binding thereof being detected in response to radiation from each cavity indicative of a change in the standing wave pattern.

Abstract: Resonant sensors and molecule detection methods utilizing split frequency. Optical energy is introduced into a microcavity, such as a toroid-shaped or spherical microcavity. A portion of the optical energy is backscattered and interacts with the introduced optical energy to form first and second modes of optical energy at respective first and second frequencies, also referred to as split frequency or mode doublets. One or more molecules bind to an outer surface of the microcavity and interact with an evanescent field of optical energy resonating within the microcavity. Binding of one or more molecules to the outer surface is detected based at least in part upon a change of the split frequency relative to a baseline split frequency.

Abstract: Apparatus and method for detecting an analyte in a sample based on optical interference. The apparatus includes a light source, detector unit and one or more disposable detector tips. The apparatus also includes an optical coupling assembly that couples light from the source to the detector tips, and from the detector tips to the detector unit.

Abstract: A system includes a plurality of optical resonators, a light source, an optical fiber that couples the plurality of optical resonators to the light source, and a detector that is coupled to the plurality of optical resonators. The detector is configured to detect an energy in the plurality of optical resonators.

Abstract: Two optical wavelengths are used to interrogate a fiber optic Fabry-Perot sensor having a moveable diaphragm that changes the width of a gap between two reflective surfaces. By picking the right operating point for the gap, the power output for one wavelength increases as the gap width changes and the power for the other wavelength decreases. A ratio of the difference of the two powers over the sum of the two powers is formed to generate a detected signal independent of power and phase fluctuations in a fiber between signal sources and sensor and between sensor and detector. This ratio, which is called the visibility, has a response proportional to the pressure of acoustic disturbances that move the diaphragm. The push-pull sensor can be used with both TDM and CW fan-out array architectures.

Abstract: A method and system are disclosed for detecting the presence of a perturbation of a microresonator including the step of exciting at least first and second resonant guided optical modes of a microresonator with a light source that is in optical communication with the microresonator. The method further includes inducing a first frequency shift in the first resonant guided optical mode and a second frequency shift in the second resonant guided optical mode, wherein the second frequency shift can be zero. Another step of the method is comparing the first frequency shift and the second frequency shift.

Abstract: A differential pressure measuring system includes a light source for emitting a light, a first transducer for attenuating the intensity of the emitted light in a first range, depending on a first pressure, and providing a first light, a second transducer for attenuating the intensity of the first light in a second range, depending on a second pressure, and providing a second light, a feedback circuit for adjusting the intensity of the emitted light to maintain the intensity of the second light in the second range constant, and a measuring module for measuring a differential pressure between the first and second pressures, based on the intensities of the second light in the first and second ranges.

Abstract: A method for fabricating a sensor, a sensor so fabricated, and a method for sensing a stimulus are provided. The method includes providing an elongated open channel, such as, a V-groove, in a substrate, the open channel providing a first surface; removing at least some material from at least a portion of the open channel to provide a second surface displaced from the first surface; positioning a diaphragm on the second surface; and positioning an elongated wave-guide having a beveled end in the elongated open channel wherein the beveled end is positioned over the diaphragm to define an interferometric cavity between the diaphragm and the outer surface of the wave-guide. The sensor so fabricated can provide an effective sensor for detecting acoustic emission waves, among other pressure waves.

Abstract: An optical device is presented for use in modulation of light and/or in sensing an external field, by at least partially, directly or indirectly exposing the device to the controllable or unknown external field. The device comprises a waveguide structure configured to define at least a first light channel having a light input and a light output, and having a first deformable resonating structure. The device thereby allows exposure of said at least first channel to the external field of the kind affecting a deformation of the first resonant structure thus causing a change in the first resonant wavelength, resulting in a corresponding change in at least one parameter of light output from said first channel, said change in the output light parameter being indicative of the external field.

Abstract: A dome-shaped chemical sensing probe comprises an optical fiber or may be mounted on an optical fiber. The probe has a chemically sensitive measuring material which exhibits a change in volume and/or a change in refractive index in the presence of a given chemical. The change in volume and/or refractive index gives a change in an optical path length through the probe which can be measured interferometrically.

Abstract: Techniques and devices based on transverse magnetic (TM) and transverse electric (TE) modes in an optical resonator or interferometer to provide sensitive optical detection with insensitivity to a change in temperature.

Abstract: There are several different applications where it is desirable to increase the amount of material that can be introduced to the surface of a microresonator that has whispering gallery modes. The use of a porous surface on the microresonator permits greater amounts of the material to be captured on or near the surface of the microresonator, resulting in an increased optical interaction between the material and the light propagating in the whispering gallery mode(s) of the microresonator.

Abstract: A method for optical spectrum analysis provides a tunable optical filter and scans a wavelength range of an optical signal that is larger than the free spectrum range of the tunable optical filter. The optical signal is filtered through the tunable optical filter. Separate multiple optical orders of the wavelengths scanned and filtered by the tunable optical filter are individually detected.

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.