Abstract: A Fabry-Perot (FP) interferometer includes substantially parallel first and second reflecting surfaces spaced apart by an optical gap between the first and second reflecting surfaces. The FP interferometer also has a mechanism for controlling the optical gap. The mechanism includes a plurality of electrostatic control plates. Each electrostatic control plate has a fixed control-plate area. Each control plate is adapted to control the optical gap by application of a control-plate voltage. The control-plate areas are related by integral ratios.

Abstract: A method and apparatus for reducing crosstalk between sensors in an inline Fabry-Perot (FP) sensor array. The inline FP sensor array comprises a plurality of fiber Bragg gratings arranged periodically along an optical fiber. The sensors are formed between each of the Bragg gratings. A light source provides multiplexed pulses as interrogation pulses for the array. The light pulses are applied to one end of the sensor array and a light detector detects reflected pulses. The detected pulses comprise a composite of reflections from all the Bragg gratings along the fiber. The apparatus processes the detected signals using an inverse scattering algorithm to detect an accurate phase response from each of the Bragg sensors while reducing crosstalk from other Bragg sensors within the array. One form of inverse scattering algorithm is a layer-peeling algorithm.

Abstract: Multiple wavelength spectrometers can be tuned to particular wavelengths. A dual wavelength spectrometer can include a spectrometer configured to detect at least some wavelengths that fall within the ultraviolet (UV) spectrum and a spectrometer configured to detect at least some wavelengths that fall within the visible spectrum. In some embodiments, a UV light spectrometer and a visible light spectrometer are disposed adjacent one another on a single substrate. A dual wavelength spectrometer can be used for analyzing bioaerosols, as well as for numerous other applications.

Abstract: A method and system for optical measurement via a resonator having a non-uniform phase profile provides a mechanism for measuring and/or detecting sub-micron surface features with increased resolution. A second surface forming part of a resonator is illuminated through a first partially reflective surface that has a non-uniform phase profile that transitions from negative to positive phase with respect to a resonance phase value of the resonator. As a result, a reduced spot size is produced at the second surface, which enhances the resolution of a measurement and/or detection of surface features on the second surface. Additionally, if a discontinuity is provided in the non-uniform phase profile, interaction of the discontinuity with surface features of the second surface will provide enhanced resolution of the surface features. The resolution of the system is improved over the resolution that can be attained using a Fabry-Perot resonator.

Abstract: A method for measuring the cavity length of a remote sensing interferometer by locally replicating the state of the remote sensing interferometer by way of a local interferometer. The local interferometer is produced by micro-electromechanical micro machining techniques, thus obtaining a highly accurate and reliable fiber optic sensing at a cost comparable to electronic sensing devices.

Abstract: A stepped etalon having a top surface and two bottom surfaces that are parallel to the top surface and are each positioned at different distances from the top surface. Each bottom surface has an edge, wherein the edges face one another and a sloping step is positioned between the two edges so that rays from a beam of light projected onto the top surface of the etalon strike the step at the Brewster angle and pass through the etalon without any light being reflected back therein.

Abstract: A method for determining the voltage sensitivity of the distance between the mirrors of a Fabry-Perot interferometer in a measuring device, which is intended to measure a predefined gas (CO2), of which at least one absorption maximum or minimum is known. At least two calibration point are defined device specifically using a reference gas (N2) in controlled conditions. A ‘virtual’ signal-control-voltage sensitivity curve, is formed with the aid of the calibration points formed using the reference gas (N2), ratios of the measurement points of the predefined gas (CO2) and of the corresponding values of the reference-gas curve are formed, and at least one voltage value corresponding to the minimum or maximum is defined from the ratios, in which case, on the basis of the wavelengths of the absorption minima or maxima of the gases (CO2, N2) being measured, the voltage sensitivity of the distance between the mirrors can be defined unequivocally.

Abstract: A sensor and method for using the same is disclosed. The sensor includes an optical cavity defined by first and second mirrors that have a spacing therebetween that varies in response to a force applied to the sensor and to a control voltage. The sensor has a drive circuit that measures light leaving an output port that samples light in said cavity and applies the control voltage to the optical cavity such that the spacing between the mirrors remains at a predetermined value independent of the force, the control voltage determining an output signal that provides a measurement of the force applied to the optical cavity. In one embodiment, the first mirror is fixed to the second mirror by a spring mechanism that causes the first mirror to move away from the second mirror, and the control voltage causes the first mirror to move toward the second mirror.

Abstract: A coefficient of linear expansion measuring apparatus includes: two reflection plates between which a sample is put, a container to house them, which is filled with a gas having known rate of a refractive index variation, a temperature regulating member to set a temperature in the container variably, a light source to irradiate an irradiating light to reflecting surfaces of the reflection plates, a light receiving element to receive reflected lights in which the lights interferes each other and detecting a light intensity thereof, and a calculating member to calculate a coefficient of linear expansion of the sample, wherein: the calculating member calculates an optical path length variation between the reflecting surfaces from an output variation of the light receiving element, and calculates a length variation of the sample by correcting a part of the optical path length variation derived from the refractive index variation of the gas caused by the temperature variation.

Abstract: This invention relates to an optical displacement sensor element, e.g. for use in a pressure sensor or a microphone, comprising two essentially flat surfaces being separated by a cavity being defined by a spacer, the distance between the surfaces being variable thus providing a displacement sensitive Fabry-Perot interferometer. Both of said surfaces are at least partially reflective, and in that said first surface is provided with at least one optical detector, and one of surfaces being provided on an at least partially transparent material.

Abstract: The present invention provides a relatively simple etalon testing system and process for measuring cavity error of etalons to high precision. It works equally well on solid and air-spaced designs. This invention should be a great aid in the manufacture of high performance etalons, separating out the geometric and reflectivity finesses. The present invention permits measurement of etalon spacings to an accuracy of better than ?/1000 (i.e., about 63 picometers [6.3×10?11 m] when using a HeNe test laser). In a preferred process an etalon under examination is mounted on a rotational stage illuminated with a collimated beam from a HeNe laser. Reflections from the etalon are imaged on a screen to produce interference fringes which are monitored by a CCD camera. The etalon is then pivoted about an axis perpendicular to the laser beam and images of the interference patterns are recorded periodically to produce a plot of intensity vs. pivot angle over a pivot range sufficient to include at least one extinction cycle.

Abstract: A wavelength monitoring device for monitoring a beam of light is disclosed having a beam splitter, with opposing first and second spaced apart faces, for receiving optical radiation from the beam of light to be monitored. In operation the first face reflects a first portion of the optical radiation to a first photodiode. The second face includes a grating for reflecting a second portion of the optical radiation to the first photodiode. The grating also reflects a third portion of optical radiation to a second photodiode. The light received by the second photodiode corresponds proportionally to optical power of the incident beam of light. The first photodiode is for detecting a wavelength characteristic of the composite beam and is located so as to receive the first portion and the second portion of optical radiation after the first portion and the second portion of optical radiation have optically interfered to form a composite beam.

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 method and apparatus for reducing crosstalk between sensors in an inline Fabry-Perot (FP) sensor array. The inline FP sensor array comprises a plurality of fiber Bragg gratings arranged periodically along an optical fiber. The sensors are formed between each of the Bragg gratings. A light source provides multiplexed pulses as interrogation pulses for the array. The light pulses are applied to one end of the sensor array and a light detector detects reflected pulses. The detected pulses comprise a composite of reflections from all the Bragg gratings along the fiber. The apparatus processes the detected signals using an inverse scattering algorithm to detect an accurate phase response from each of the Bragg sensors while reducing crosstalk from other Bragg sensors within the array. One form of inverse scattering algorithm is a layer-peeling algorithm.

Abstract: A method for calibrating an interferometer uses an actuator adapted to control an optical gap in response to application of an electrical signal. The interferometer is illuminated with a beam of light having a predetermined substantially monochromatic wavelength, oriented at a first predetermined angle of incidence, and light reflected from the interferometer at a second predetermined angle is detected while varying an electrical signal applied to the actuator, thereby establishing a calibrated relationship between the applied electrical signal and an optical path length of the interferometer.

Abstract: A first beam of light from a laser is split by a beam splitter into a reference beam and at least one second beam of light, the latter of which is directed from an optical head into an atmosphere. Light from the at least one second beam of light scattered by molecules or aerosols in the atmosphere is collected by a corresponding at least one telescope of the optical head as at least one light signal. The at least one light signal and the reference beam are simultaneously processed by different portions of a Fabry-Pérot interferometer, and resulting fringe patterns are imaged onto a detector and processed by a data processor to determine at least one associated air data product.

Abstract: A scanning optical monitoring system and method are appropriate for high speed scanning of a WDM signal band. The system and method are able to identify dropped channels or, more generally, discrepancies between the determined or detected channel inventory and a perpetual inventory for the WDM signal, which perpetual inventory specifies the channels that should be present in the WDM signal assuming proper operation of the network. The system includes a tunable optical filter that scans a pass band across a signal band of a WDM signal to generate a filtered signal. A photodetector then generates an electrical signal in response to this filtered signal. A decision circuit compares the electrical signal to a threshold and a controller, which is responsive to the decision circuit, inventories the channels in the WDM signal.

Abstract: An interferometer sensor has a two-dimensional sensor head (1) comprising a polymer film (4) of substantially uniform thickness. An interrogating signal (12) is provided to the sensor head, the interrogation signal extending across the area of the sensor head and being incident normally to the sensor head (1). An optical sensing device (16) is arranged to receive an optical output signal from the sensor head at a location remote from the sensor head. The sensor converts ultrasound signals appearing over a two dimensional surface to an optical signal pattern, using a polymer interferometer sensing film. Spatial discretisation of the ultrasound signal pattern is performed by an optical sensing device. Such optical devices can be arranged having sufficiently high resolution to enable beam-steering imaging to be performed, including imaging outside the footprint of the sensor head.

Abstract: An optical cavity is combined with a MUX or a de-MUX device having substantially the same free-spectral range in order to enhance the bandwidth of the device. The optical cavity can be tuned to shift the frequencies of maximum insertion loss to match the center frequency of each channel. The reflectivities of the reflective surfaces of the cavity are judiciously selected to produce the insertion-loss spectrum needed to optimize the desired result. Multiple cavities can be used in series to refine the shape of the pass-band spectrum. A frequency window is used to fine tune the free-spectral range of the cavity and to shift the peaks of its insertion-loss spectrum to the desired frequencies. Inner and outer cavity surfaces are oriented to eliminate interference from secondary reflections.

Abstract: An optical spectrum analyzer apparatus for analyzing the spectral content of a light signal. The optical spectrum analyzer apparatus includes an optical tapped delay line (OTDL) unit as a light dispersing unit to provide an analyzer apparatus having increased resolution.

Abstract: A method for locking the wavelength of a laser uses a non-planar etalon, for example a non-parallel etalon, to produce a periodic spatial interference pattern, typically in the light reflected from the non-planar etalon. At least three different portions of the interference pattern are detected to generate at least three respective detection signals. A feedback signal is generated using the detection signals, and the operating wavelength of the laser is adjusted in response to the feedback signal.

Abstract: Integrated spectroscopy systems are disclosed. In some examples, integrated tunable detectors, using one or multiple Fabry-Perot tunable filters, are provided. Other examples use integrated tunable sources. The tunable source combines one or multiple diodes, such as superluminescent light emitting diodes (SLED), and a Fabry Perot tunable filter or etalon. The advantages associated with the use of the tunable etalon are that it can be small, relatively low power consumption device. For example, newer microelectrical mechanical system (MEMS) implementations of these devices make them the size of a chip. This increases their robustness and also their performance. In some examples, an isolator, amplifier, and/or reference system is further provided integrated.

Abstract: A method of tuning a resonant cavity of an FP (Fabry-Perot) interferometer in a DLD (diffractive light device) MEMS (microelectromechanical system) device, wherein the FP interferometer has a top plate and a bottom plate, and wherein the method comprises; using first and second electromechanical transducers to independently change a distance between the top and bottom plates of the FP interferometer.

Abstract: An interferometer includes: a first glass plate optically coupled to a second glass plate, forming an optical interferometric cavity therebetween; a first reflective coating coupled to the first glass plate within the optical interferometric cavity, where the first reflective coating is partially reflective; a second reflective coating coupled to the second glass plate within the optical interferometric cavity, where the second reflective coating is at least partially reflective; and a tuning plate residing within the interferometric cavity and optically coupled to the first and second reflective coatings, where the tuning plate comprises a photosensitive material, where a refractive index of the photosensitive material may be modified by exposure to light.

Abstract: An interleaver device and associated methods of manufacturing and calibration that use a laser bending technique to adjust the relative position of interferometers of the interleaver. The interleaver device includes a laterally divided housing with two lateral portions separated by supports. The supports are web like structures, the length of which can be adjusted in a predictable or measurable manner in response to a laser beam. The laser bending calibration and manufacturing technique uses a laser and a feedback and control system to adjust the spacing and angular relation between the lateral portions by partially melting one or more of the supports. The feedback and control system includes an optical detector, a computer, and a positioning system. This combination of components allows the interleaver device to be calibrated to precisely adjust the separation between channels within a WDM optical signal.

Abstract: A laser signal is monitored. The laser signal is forwarded to an etalon. Light transmitted through the etalon is detected. Light reflected from the etalon is detected. A ratio is calculated from the detected light transmitted through the etalon and the light reflected from the etalon.

Abstract: A method and apparatus for reducing crosstalk between sensors in an inline Fabry-Perot (FP) sensor array. The inline FP sensor array comprises a plurality of fiber Bragg gratings arranged periodically along an optical fiber. The sensors are formed between each of the Bragg gratings. A light source provides multiplexed pulses as interrogation pulses for the array. The light pulses are applied to one end of the sensor array and a light detector detects reflected pulses. The detected pulses comprise a composite of reflections from all the Bragg gratings along the fiber. The apparatus processes the detected signals using an inverse scattering algorithm to detect an accurate phase response from each of the Bragg sensors while reducing crosstalk from other Bragg sensors within the array. One form of inverse scattering algorithm is a layer-peeling algorithm.

Abstract: A linear interferometric sensor system in which the light output from the interferometric sensor is optically bandpass filtered before conversion to an electrical signal by an adjustable band-pass filtering device and the center wavelength of the adjustable band-pass filtering device is controlled by a feedback circuit responsive to the steady state component of the electrical signal corresponding to the filtered sensor return. In a preferred embodiment, the adjustable band-pass filtering device is an electrically tunable optical filter. The invention is particularly useful in self calibrating interferometric/intensity-based sensor configuration, but can be used with other linear interferometric sensor configurations.

Abstract: A spectrally tunable optical detector and methods of manufacture therefore are provided. In one illustrative embodiment, the tunable optical detector includes a tunable bandpass filter, a detector and readout electronics, each supported by a different substrate. The substrates are secured relative to one another to form the spectrally tunable optical detector.

Abstract: A system for monitoring an optical output/wavelength is employed to be used for a WDM system having a narrow channel space by structuring an etalon and photodiode as an integrated structure.

Abstract: An improved band pass interferometer for use as a high resolution wavelength selection unit comprising, as main elements, an input optical port (optical fiber) together with a fiber optic collimator for generating a narrow incoming collimated beam, two plane-parallel highly reflective surfaces with low reflection losses, one being totally reflective, (i.e. very little intensity of the light beam incident thereon should pass through the reflective surface,) the other being partially reflective, (i.e., a portion of a reflected light beam, more specifically its intensity, incident thereon should pass through the partially reflective surface becoming an output beam,) which splits the incoming narrow incoming collimated beam into a finite number of output beams, an optical medium located between the reflective surfaces, and a beam focusing element which collects all the output beams and focuses them into an output optical port (optical fiber). There is also provided a refractive index adjuster, such as, e.g.

Abstract: An optical instrument including: a thermo-optically tunable, thin film, free-space interference filter having a tunable passband which functions as a wavelength selector, the filter including a sequence of alternating layers of amorphous silicon and a dielectric material deposited one on top of the other and forming a Fabry-Perot cavity structure having: a first multi-layer thin film interference structure forming a first mirror; a thin-film spacer layer deposited on top of the first multi-layer interference structure, the thin-film spacer layer made of amorphous silicon; and a second multi-layer thin film interference structure deposited on top of the thin-film spacer layer and forming a second mirror; a lens for coupling an optical beam into the filter; an optical detector for receiving the optical beam after the optical beam has interacted with the interference filter; and circuitry for heating the thermo-optically tunable interference filter to control a location of the passband.

Abstract: A stable scanning or non-scanning Fabry-Perot interferometer and a method for stabilising the interferometer. The interferometer is composed of two plane mirrors arranged parallel to one another with a preselected optical distance between the optical surfaces of the mirrors. The interferometer radiates an output light signal in response to a light input signal applied parallel to the optical axis of the interferometer. The interferometer is stabilised by providing an arrangement for passing a plurality of reference light beams through the interferometer, the reference light beams being inclined at a preselected angle to the optical axis of the interferometer.

Abstract: A method and an apparatus for enhancing a resolving power of a tunable optical filter. An optical input is applied to the tunable filter. An electrical signal is applied to the tunable optical filter. The electrical signal has a first component that has a first frequency and a second component that has a second frequency. The second frequency is higher than the first frequency. An optical output of the tunable optical filter is applied to a photodetector. The electrical output from the photodetector is applied to a lock-in detector. The lock-in detector receives an input from frequency doubling circuitry. An output of the lock-in detector is monitored.

Abstract: The present invention discloses a Fabry-Perot device compensating for an error of full-width-at-half-maximum (FWHM) and a manufacturing method for the device. The Fabry-Perot device mainly consisted of a Fabry-Perot resonant cavity for a light to pass through. The cavity includes a first reflecting surface with a first reflectance for partly reflecting the light, and a second reflecting surface with a second reflectance for partly reflecting the light. In addition, a distance between the first and second reflecting surfaces may be adjusted according to the first and second reflectance, and thereby compensating for the error of FWHM caused by the first and second reflectance.

Abstract: An interferometer comprises a membrane, a substrate, and a support structure. The membrane comprises a first reflector. The substrate comprises a second reflector. The support structure circumferentially couples the membrane to the substrate and orients the first reflector parallel to and facing the second reflector.

Abstract: A method and apparatus for measuring bandwidth of light emitted from a laser which may comprise: first and second wavelength sensitive optical bandwidth detectors providing, respectively, an output representative of a first parameter indicative of the bandwidth of the emitted light as measured respectively by the first and second bandwidth detectors, and an actual bandwidth calculation apparatus adapted to utilize these two outputs as part of a multivariable linear equation employing predetermined calibration variables specific to either the first or the second bandwidth detector, to calculate a first actual bandwidth parameter or a second actual bandwidth parameter. The first actual bandwidth parameter may be a spectrum full width at some percent of the maximum (“FWXM”), and the second actual bandwidth parameter may be a portion containing some percentage of the energy (“EX”).

Abstract: The invention relates generally to optical interference filters and interferometers. Methods, devices and device components for optical signal generation and processing using optical interference filters and interferometers are presented. The invention provides optical interference filters and interferometers having a selected cumulative reflectance phase dispersion capable of providing substantially independent selectable resonance frequency and free spectral range. An exemplary interference filter of the present invention provides a multi-peak transmission spectrum with substantially independent, selectable control over absolute transmission band frequencies and relative transmission band spacing. The methods and devices provided herein are particularly well suited for frequency matching optical signals to a selected frequency standard, such as the International Telecommunication Union frequency standard.

Abstract: A wavemeter for determining a wavelength of an incident optical beam comprises four optical components, each being arranged in the incident optical beam or in a part of it, providing a path with a respective effective optical length, and generating a respective optical beam with a respective optical power depending on the wavelength of the incident optical beam. The optical powers oscillate periodically with increasing wavelength, and a phase shift of approximately pi/2 is provided between two respective pairs of the four optical components. Respective power detectors are provided, each detecting a respective one of the optical powers. A wavelength allocator is provided for allocating a wavelength to the incident optical beam based on the wavelength dependencies of the detected first, second, third, and fourth optical powers.

Abstract: An apparatus is described for controlling the optical path length in an optical device, e.g. an interferometer, and more importantly to maintaining the optical path length difference in an interferometer. The apparatus may include an adjustable plate optically coupled with a beamsplitter. The plate may be rotated such that its surface receives light propagated from the beamsplitter at a non-zero incident angle. In one embodiment, temperature sensitivity is addressed by ensuring that the refractive index of the plate is greater than the refractive index of the beamsplitter. In another embodiment, the apparatus includes combination spacers having a component selected in dependence upon a composition, thickness, and orientation of the adjustable plate.

Abstract: The measurement of the wavelength shifts in the reflectometric interference spectra of a porous semiconductor substrate such as silicon, make possible the highly sensitive detection, identification and quantification of small analyte molecules. The sensor of the subject invention is effective in detecting multiple layers of biomolecular interactions, termed “cascade sensing”, including sensitive detection of small molecule recognition events that take place relatively far from the semiconductor surface.

Abstract: The invention relates to a method of extending the capture range (CR) of a wavelength monitor for the lasers of a wavelength division multiplex (WDM) transmission system wherein the capture range (CR) comprises one wavelength period (FSR) of a periodic error signal (E) generated with the aid of the wavelength filter (4), the capture range contains a desired wavelength (?0) of a plurality of equidistant wavelengths (?i, ?i+1, ?i+2, . . . ), each of the lasers of the WDM transmission system is set at a desired wavelength (?0) by comparing the error signal (E) with an comparison value (C1 or C2), that is unique in the capture range (CR) for a chosen slope sign, the wavelength period (FSR) of the error signal (E) is set such that it corresponds to double the wavelength spacing (A) of two adjacent wavelengths of the WDM transmission system and the desired wavelength (?0) is set taking into account the slope sign of the error signal (E), and further relates to a wavelength monitor and laser system therefor.

Abstract: The method for making the fiber optic Fabry-Perot sensor includes securing an optical fiber to a substrate, and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot sensor. Preferably, an adhesive directly secures the at least one pair of optical fiber portions to the substrate. The opposing spaced apart optical fiber end faces are self-aligned because the pair of optical fiber end portions are formed from a single fiber which has been directly secured to the substrate. Also, each of the self-aligned spaced apart optical fiber end faces may be substantially rounded due to an electrical discharge used to form the gap. This results in integral lenses being formed as the end faces of the fiber portions.

Abstract: There are disclosed a wavelength monitoring device of tunable laser sources and a method thereof. A Fabry-Perot etalon is provided to detect the wavelength drift, and furthermore, a Fabry-Perot laser diode or a light emitting diode is provided to recognize the channel of the wavelength. The wavelength drift is used to determine the junction voltage of each corresponding channel in advance. Then, the actually detected junction voltage of the diode is used to determine the channel of the wavelength, thereby accurately detecting the actual channel wavelength.

Abstract: The invention features methods and systems in which wavelength-tune PSI data is analyzed in the frequency domain to produce spectrally separated frequency peaks each corresponding to a particular pair of surfaces in an interferometric cavity defined by multiple pairs of surfaces. Each frequency peak provides optical path length information about a corresponding pair of surfaces in the cavity. As a result, the interferometric data from such cavities provides simultaneous information about multiple surfaces.

Abstract: A method and system for performing swept-wavelength measurements within an optical system incorporating a reference resonator provides improved operation in resonator-enhanced optical measurement and data storage and retrieval systems. The system includes an illumination subsystem, an illumination coupler for producing a measurement beam and a reference beam from an output of the optical illumination source, a reference resonator for receiving the reference beam, a measurement resonator for receiving the measurement beam, at least two detectors, one optically coupled to the reference resonator and one optically coupled to the measurement resonator, and a time-domain measurement system coupled to the detectors for comparing detected optical signals received from the resonators. The detected signal from the reference resonator is used to compensate or detect variations in the wavelength of the illumination system, improving the resolution and accuracy of the measurement provided by the measurement resonator.

Abstract: MEMS Device Having Contact and Standoff Bumps and Related Methods. According to one embodiment, a movable MEMS component suspended over a substrate is provided. The component can include a structural layer having a movable electrode separated from a substrate by a gap. The component can also include at least one standoff bump attached to the structural layer and extending into the gap for preventing contact of the movable electrode with conductive material when the component moves.

Abstract: The invention allows for the accurate, real-time readout of the optical frequency of a swept-wavelength laser device by counting the number of fringes of a calibrated etalon that occur as the laser is swept. The distinguishing feature of the present invention is that the etalon fringe signal is phase-locked to a slave signal of a higher multiple frequency. The higher frequency of the slave signal divides the frequency interval of the etalon fringe spacing by the additional frequency multiple. The slave signal therefore generates a scale for optical frequency that is of higher resolution than possible with the etalon alone. The phase-lock also insures that the slave signal tracks monotonic scans of the optical frequency regardless of scan profile. The invention also allows for the precise, real-time control of the optical frequency of a laser during the sweep of the laser.

Abstract: An air-density-tuned interferometer includes: a hermetically sealed enclosure; a front window coupled to the hermetically sealed enclosure; an interferometer residing within the hermetically sealed enclosure; and a pressure changing device coupled to the hermetically sealed enclosure. The interferometer within the enclosure includes: a first glass plate optically coupled to the front window; a first reflective coating coupled to the first glass plate; a second reflective coating optically coupled to the first reflective coating; a second glass plate coupled to the second reflective coating; and a plurality of spacers coupled to the first and second glass plates, forming an optical interometric cavity therein. The pressure changing device manipulates the gas pressure within the cavity.

Abstract: A laser difference frequency discriminator that detects the difference between two laser frequencies and outputs a voltage near baseband that is related to the difference frequency. This discriminator power splits a laser beam containing the two laser frequencies into two paths, one which is sent down a delay line to a photo detector while the other is sent directly to a photodiode; there may be an optional phase shifter in either path. The relative phases of the heterodyne signals from the photo detectors are compared in a phase detector, its output voltage is related to the phase difference, which is, in turn, related to the difference frequency. This discriminator has applications in microwave generation, laser radar, and optical communications.