Abstract: Provided are a light guide plate, an area light source device, a display device, and manufacturing method for the light guide plate such that the occurrence of uneven luminance is suppressed. The light guide plate is characterized in that the light guide plate has a light entrance surface through which light enters, a light exit surface intersecting with the light entrance surface and through which light is output, and an opposite surface facing the light entrance surface, wherein the light entering through the light entrance surface is guided to the opposite surface side and output from the light exit surface, and the refractive index Nx in a direction perpendicular to the light entrance surface is higher than the refractive index Ny in a direction parallel to the light exit surface and parallel to the light entrance surface.

Abstract: The present invention is in the field of a quantum wavelength converter between a microwave signal and an optical signal and vice versa. In the converter a nanoscale cavity optomechanical circuit is used in which optomechanical cavities supporting colocalized infrared photons and microwave phonons are combined with a photonic and a phononic waveguide.

Abstract: A holographic display is comprised of space-multiplexed elemental modulators, each of which consists of a surface acoustic wave transducer atop an anisotropic waveguide. Each “line” of the overall display consists of a single anisotropic waveguide across the display's length with multiple surface acoustic wave transducers spaced along the waveguide length, although for larger displays, the waveguide may be divided into segments, each provided with separate illumination. Light that is undiffracted by a specific transducer is available for diffraction by subsequent transducers. Per transducer, guided-mode light is mode-converted to leaky-mode light, which propagates into the substrate away from the viewer before encountering a volume reflection grating and being reflected and steered towards the viewer. The display is transparent and all reflection volume gratings operate in the Bragg regime, thereby creating no dispersion of ambient light.

Abstract: An optical switch includes a bus waveguide supported by a substrate, an actuation electrode supported by the substrate, the actuation electrode having fins that protrude in a direction perpendicular to the substrate and to the bus waveguide, and a reaction electrode having interdigitated fins configured to form a comb drive with the actuation electrode. When a voltage difference between the reaction electrode and the actuation electrode is less than a lower threshold, the reaction electrode is positioned a first distance from the bus waveguide, when the voltage difference between the reaction electrode and the actuation electrode is greater than an upper threshold, the reaction electrode is positioned a second distance from the bus waveguide, and the second distance is less than the first distance.

Abstract: There are provided a photoacoustic image generation apparatus and an insert that separately acquire both positional information and surrounding environment information of the insert. A puncture needle is at least partially inserted into a subject. An optical fiber guides light with a first wavelength and light with a second wavelength which are incident while being switched. The light guided by the optical fiber is emitted from a light emitting portion. A light absorption member absorbs the light with the first wavelength emitted from the light emitting portion, generates photoacoustic waves, and transmits the light with the second wavelength emitted from the light emitting portion.

Abstract: System, methods, and other embodiments described herein relate to a photonic apparatus including integrated phase measurement. The photonic apparatus includes a phase shifter operably connected with a source optical waveguide to receive a source light wave and to shift a source phase of the source light wave to produce a shifted light wave with a shifted phase that is different from the source phase. The photonic apparatus includes an output optical waveguide connected with the phase shifter to provide the shifted wave and a reference optical waveguide operably connected with the source optical waveguide to provide the source light wave. The photonic apparatus includes a combiner to combine the shifted light wave with the source light wave to produce a combined light wave. The photonic apparatus includes a detector to determine a difference in phases between the shifted phase and the source phase as embodied in the combined wave.

Abstract: An optical waveguide device 1 includes a thin layer 3 and a ridge portion 5 loaded on the thin layer 3. The thin layer 3 is made of an optical material selected from the group consisting of lithium niobate, lithium tantalate, lithium niobate-lithium tantalate, yttrium aluminum garnet, yttrium vanadate, gadolinium vanadate, potassium gadolinium tungstate; and potassium yttrium tungstate. The ridge portion 5 is made of tantalum pentoxide and has a trapezoid shape viewed in a cross section perpendicular to a direction of propagation of light. The ridge portion is not peeled off from the thin layer in a tape peeling test.

Abstract: A substrate (102) having a piezoelectric effect, optical waveguide (138a, 140a, 138b, 140b, and the like) formed on the substrate, and a plurality of bias electrodes (152a, 152b, and the like) that control an optical wave (s) which propagate through the optical waveguides are provided, and the bias electrodes are constituted and/or disposed such that an electrical signal applied to one of the bias electrodes is prevented from being received by another one of the bias electrodes through a surface acoustic wave.

Abstract: A high-frequency light-generated focused ultrasound (LGFU) device is provided. The device has a source of light energy, such as a laser, and an optoacoustic lens comprising a concave composite layer with a plurality of light absorbing particles that absorbs laser energy, e.g., carbon nanotubes, and a polymeric material that rapidly expands upon exposure to heat, e.g., polydimethylsiloxane. The laser energy is directed to the optoacoustic lens and thus can generate high-frequency (e.g., ?10 MHz) and high-amplitude pressure output (e.g., ?10 MPa) focused ultrasound. The disclosure also provides methods of making such new arcuate optoacoustic lenses, as well as methods for generating and using the high-frequency and high-amplitude ultrasound, including for surgery, like lithotripsy and ablation.

Abstract: A system and method for interactive therapy and diagnosis of a human or animal comprising at least one first radiation source for emission of a diagnostic radiation, at least one second radiation source for emission of a therapeutic radiation, and at least one radiation conductor adapted to conduct radiation to a tumor site at or in said human or animal. A non-mechanical operation mode selector directs the therapeutic radiation and/or the diagnostic radiation to the tumor site through the radiation conductors. The operation mode selector means is preferably a non-mechanical optical switch and/or an optical combiner. The system may be used for interactive interstitial photodynamic tumor therapy.

Abstract: An optical waveguide (2) arranged to transmit light under total internal reflection has a first diffractive grating region (8) arranged to receive light and diffract the received light along the optical waveguide (2), an intermediate diffraction grating (10) optically coupled to the first diffractive grating region (8) arranged to expand received light in a first dimension and a second diffractive grating region (9) optically coupled to the intermediate diffraction grating (10) arranged to expand light in a second dimension, orthogonal to the first dimension and to output the light expanded in the first and second dimensions from the optical waveguide (2) by diffraction. The first and second diffractive grating regions (8,9) are fabricated as a common grating whereas the second grating is fabricated above the common grating in an area where the common grating is erased by a coating.

Abstract: A waveguide lens includes a substrate, a planar waveguide, a media grating, and a pair of electrode. The planar waveguide is formed on the substrate and configured to couple with a laser light source that emits a laser beam into the planar waveguide along an optical axis. The media grating is formed on the planar waveguide and arranged symmetrically about a widthwise central axis that is collinear with the optical axis. The electrodes are formed on the substrate, positioned at two opposite sides of the waveguide lens, and arranged symmetrically about the optical axis.

Abstract: An electro-optic structure, which may comprise an acousto-optic modulator for use in an opto-acoustic oscillator, comprises a plurality of rigidly connected resonator core components located movably separated over a substrate and anchored to the substrate at an anchor point. An actuator electrode is located separated from a first one of the rigidly connected resonator core components and an optical waveguide is located separated from a second one of the rigidly connected resonator core components. Radio frequency and direct current actuation of the actuator electrode provides a mechanical vibration in the first rigidly connected resonator core component that is mechanically coupled to the second rigidly connected resonator core component which serves to optically modulate light transported through the wave guide. Reverse operation is also contemplated. Embodiments also contemplate a third rigidly connected resonator core component as a radiation pressure driven detector.

Abstract: A tunable Radio Frequency (RF) filter device includes a tunable optical source configured to generate an optical carrier signal, and a modulator coupled to the tunable optical source and configured to modulate the optical carrier signal with an RF input signal. The tunable RF filter device may also include first and second optical waveguides coupled to the modulator and having first and second dispersion slopes of opposite sign, and an optical-to-electrical converter coupled to the first and second optical waveguides and configured to generate an RF output signal with a frequency notch therein based upon the tunable optical source.

Abstract: A tunable Radio Frequency (RF) filter device includes a tunable optical source generating an optical carrier signal, and a modulator coupled to the tunable optical source and modulating the optical carrier signal with an RF input signal. The tunable RF filter device may include first and second optical waveguide paths coupled to the modulator and having first and second dispersion slopes of opposite sign from each other, one or more of the first and second optical waveguide paths comprising an optical splitter and combiner pair therein, and an optical-to-electrical converter coupled to the first and second optical waveguide paths and generating an RF output signal with a frequency notch therein based upon the tunable optical source.

Abstract: A tunable Radio Frequency (RF) filter device includes a tunable optical source configured to generate an optical carrier signal, and a modulator coupled to the tunable optical source and configured to modulate the optical carrier signal with an RF input signal. The tunable RF filter device may also include first and second optical waveguides coupled to the modulator and having first and second dispersion slopes of opposite sign, and an optical-to-electrical converter coupled to the first and second optical waveguides and configured to generate an RF output signal with a frequency notch therein based upon the tunable optical source.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: An acousto-optical filter element (114) is provided which has an acousto-optical crystal (118) having an acoustic signal transmitter (120) for generating acoustic signals in the acousto-optical crystal (118). The acousto-optical crystal (118) is designed to selectively spatially deflect light of a target wavelength from an input light beam (116) entering into the acousto-optical crystal (118), as a function of a high frequency applied to the acoustic signal transmitter (120), and to thereby produce a target light beam (126) having the target wavelength. In addition, the acousto-optical filter element (114) includes a spatial filter element (132) which is located in the target light beam (126) and is designed to selectively suppress the intensity of the target light beam (126) in a plane perpendicular to the propagation direction of the target light beam (126).

Abstract: The approach of one embodiment of the present invention is to mechanically vibrate a length of fiber optic cable transmitting coherent laser light, so that a mechanical resonance in the optical fiber is excited. This is achieved by suspending the fiber optic cable between two points and controlling both the axial tension on the suspended fiber optic cable as well as the mechanical forcing frequency. The cyclic, high-frequency mechanical perturbations of the fiber rapidly vary the path length and internal reflection angles of one or more respective modes of the transmitted laser light. In certain embodiments, the system may be tuned to induce a standing mechanical wave in the fiber. Higher-harmonic waveforms and higher amplitudes in the resonant fiber produce excellent speckle reduction and uniform intensity distributions.

Abstract: A nano-optomechanical transducer provides ultrabroadband coherent optomechanical transduction based on Mach-wave emission that uses enhanced photon-phonon coupling efficiencies by low impedance effective phononic medium, both electrostriction and radiation pressure to boost and tailor optomechanical forces, and highly dispersive electromagnetic modes that amplify both electrostriction and radiation pressure. The optomechanical transducer provides a large operating bandwidth and high efficiency while simultaneously having a small size and minimal power consumption, enabling a host of transformative phonon and signal processing capabilities. These capabilities include optomechanical transduction via pulsed phonon emission and up-conversion, broadband stimulated phonon emission and amplification, picosecond pulsed phonon lasers, broadband phononic modulators, and ultrahigh bandwidth true time delay and signal processing technologies.

Abstract: In order to create a stable non-linear optical effect with high efficiency for a plurality of input lights having different wavelengths, according to a first aspect of the present invention, provided is a wavelength conversion apparatus comprising an input section into which input light is input; a wavelength converting section that includes a polarity inverting structure whose polarity inverts periodically and that, in response to the input of light having a wavelength corresponding to the period with which the polarity inverts, converts the wavelength of the light; and a direction changing section that changes a progression direction in which the input light passes through the polarity inverting structure, according to the wavelength of the input light, without changing relative positions of the input section and the polarity inverting structure. Also provided are a light source apparatus and a wavelength converting method.

Abstract: An imaging guidewire can include optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. The guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: An acousto-optic device having a wide range of diffraction angle and an optical scanner, a light modulator, and a display apparatus using the acousto-optic device are provided. The acousto-optic device includes a core layer having a periodic photonic crystal structure in which unit cells of predetermined patterns are repeated, a first clad layer on a first surface of the core layer, the first clad layer having a refractive index that is different from a refractive index of the core layer, a second clad layer on a second surface of the core layer, the second surface being opposite the first surface, the second clad layer having a refractive index that is different from the refractive index of the core layer, and a sound wave generator configured to apply surface acoustic waves (SAW) to the core layer, the first clad layer, the second clad layer, or any combination thereof.

Abstract: An acousto-optic device includes an optical waveguide in which incident light is able to propagate; a metal layer surrounding at least a first portion of the optical waveguide; a gain medium layer disposed in the first portion of the optical waveguide; and a sonic wave generator configured to generate surface acoustic waves (SAWs) and apply the SAWs to the optical waveguide and/or the metal layer.

Abstract: An electromagnetically responsive element includes sets of arrangements of self-resonant bodies, such as atoms or quantum dots that form an effective dielectric constant, typically at or near a resonance.

Abstract: An electromagnetically responsive element includes sets of arrangements of self-resonant bodies, such as atoms or quantum dots that form an effective dielectric constant, typically at or near a resonance.

Abstract: An acoustic sensor includes at least one photonic crystal structure and an optical fiber in optical communication with the at least one photonic crystal structure. The at least one photonic crystal structure has at least one optical resonance with a resonance frequency and a resonance lineshape, wherein at least one of the resonance frequency and the resonance lineshape is responsive to acoustic waves incident upon the acoustic sensor. The acoustic sensor further includes an optical fiber in optical communication with the at least one photonic crystal structure. The optical fiber is configured to transmit light which impinges the at least one photonic crystal structure and to receive at least a portion of the light which impinges the at least one photonic crystal structure.

Abstract: The waveguide-type polarizer includes: a Z-cut lithium niobate substrate; an optical waveguide having a ridge structure and formed on the substrate; a low refractive index film formed with a thickness satisfying 0?n·t/??0.3742 (where n is a refractive index, t (?m) is the thickness of the film, and ? (?m) is the wavelength of a light wave) on the side of the ridge structure; and a high refractive index film formed with a thickness satisfying 0.089?n·/? on the low refractive index film. The width of the ridge structure is a ridge width where the distribution of ordinary light of the light waves propagated through the optical waveguide changes and the distribution of extraordinary light of the light waves does not change, the angle of the ridge structure is less than 90°, and the waveguide-type polarizer has a function of transmitting extraordinary light.

Abstract: An imaging guidewire can include optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. The guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: An acoustic sensor includes at least one structure including at least one photonic crystal slab and an optical fiber optically coupled to the at least one photonic crystal slab, and 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 structure. At least one of the resonance frequency and the resonance lineshape is responsive to acoustic waves incident upon the housing.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: Optical waveguides are provided on a substrate, a thin film whose refractive index is optically less than the refractive indices of the optical waveguides is provided on the surface of the substrate, and a surface-acoustic-wave waveguide is arranged on the thin film so as to cross the optical waveguides in a direction oblique thereto. The optical waveguides are not directly influenced by the location of the SAW waveguide and the phase matching condition of the optical waveguides is not changed, whereby the sidelobe characteristic of an optical filter is not degraded by assigning weights to the SAW intensity.

Abstract: An optical transmitter is disclosed having a temperature stabilization system for an optical filter for maintaining constant the frequency response of the filter. The filter is mounted within a housing having a substantially higher thermal conductivity. The housing may include a copper-tungsten alloy and extend along the optical axis of the filter. The housing is in thermal contact with a thermo-electric cooler (TEC) and a temperature sensor. The TEC and temperature sensor are electrically coupled to a controller which adjusts the temperature of the TEC according to the output of the temperature sensor.

Abstract: A tunable laser cavity utilizes a dispersion compensated acousto-optic tunable filter. The wavelength accuracy and stability is achieved by a wavelength locker utilizing two separate intracavity light beams without the need to use beam splitters to significantly reduce the space typically needed by a conventional wavelength locker, and provide more stable operation and easy assembly. The acoustic optical tunable filter is constructed in such a way that two transducers are bonded on the same crystal opposite to each other to create two counter propagating acoustic waves. Dispersion occurs after the collimated light diffracted by the first acoustic wave and is compensated by the second acoustic wave traveling in the opposite direction. By using different laser gain mediums, acoustic wave driving frequencies and acousto-optical crystals, this invention can be used to make tunable lasers in wide range of optical wavelengths.

Abstract: Embodiments of the inventions described herein comprise a device and method for manipulating an optical beam. The method comprises propagating an optical beam through a waveguide in proximity to a resonant cavity and pumping the resonant cavity with sufficient optical power to induce non-linearities in the refractive index of the resonant cavity. The method further comprises tuning the resonant frequency band of the resonant cavity with a modulation signal such that the optical beam is manipulated in a useful way.

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: Provided are an acousto-optic filter and an optical code division multiple access (CDMA) system using the acousto-optic filter. The acousto-optic filer includes: an acousto-optic mode converter (AOMC) converting an optical signal of a specific optical frequency corresponding to a frequency of an electric signal of an optical signal of a first mode having a predetermined optical frequency band; and a mode stripper (MS) stripping an optical signal of the optical signal of the first mode that has been converted to a second mode.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: A system and method for modulating the frequency of electromagnetic radiation utilizes a frozen shockwave in a photonic band gap structure. The structure provides a discontinuity in lattice constant that functions as a shockwave, and that does not shift its position within the structure. In addition the modulation device or structure includes an acoustic pulse generator, such as a piezoelectric transducer coupled to one end of the photonic band gap structure. The acoustic pulse generator may be driven to produce a periodic pulse in the photonic band gap structure. The frozen shockwave, a defect or discontinuity in the photonic band gap structure, is used to hold incoming electromagnetic radiation in place. The acoustic pulse passing through the photonic band gap structure Doppler shifts the frequency of the radiation. The frequency-shifted radiation is then ejected out of the frozen shockwave portion of the photonic band gap structure.

Abstract: An apparatus for performing mode scrambling in a multimode optical fibre 1 comprises an electromechanical transducer 3 and a signal generator 9. A portion of the fibre 1, which is in the form of a loop 5, is arranged with its ends 6 fixed to the transducer 3, but with the remainder of the portion being left free to vibrate. The signal generator 9 drives the transducer 3 so as to form a succession of bends of differing bend radii in the portion of the fibre as a beam of electromagnetic radiation travels through the fibre, thereby “scrambling” the beam as it travels through the fibre.

Abstract: The present invention relates to the modulation of light traveling along a waveguide, in particular to the acoustic modulation of the light. There is provide a modulator arrangement for acoustically modulating optical radiation. The modulator arrangement has: a waveguide portion formed from a flexible material; a vibrator element for generating acoustic vibrations; and, a coupling arrangement for releasably coupling the vibrating element to the waveguide portion, the coupling arrangement including a first coupling member secured to the waveguide portion, and a second coupling member secured to the vibrator element. The second coupling member is removable from the first coupling member, and the first coupling member has a substantially rigid portion for retaining the shape of the waveguide when the second coupling member is removed from the first coupling member.

Abstract: A narrow-linewidth micropulse LIDAR transmitter based on a low-SBS single clad, small-mode-area optical fiber. High narrow-linewidth peak powers are achieved through the use of an erbium doped fiber with an acoustic waveguide. Over 6 ?J per pulse (100 ns pulse width) is achieved before a weak form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.

Abstract: A Gires-Tournois etalon (GTE) (10) comprising an optical fiber (12) in which a primary chirped fiber Bragg grating (FBG) (16) is provided, an RF signal generator (20), a piezoelectric transducer (22), and a glass horn (24), for coupling an acoustic wave (26) into the fiber (12). The acoustic wave (26) causes a periodic compression within the fiber (12), which induces a low frequency periodic refractive index modulation within the grating section (14) of the fiber (12). This causes two side frequency components to be generated for each high-frequency component of the FBG (16). Two secondary grating are thus excited, having the same spectral bandwidth as the FBG (16), but a lower reflectivity and different central wavelengths. The free spectral range of the GTE (10) can be adjusted by varying the frequency of the acoustic wave (26). The reflectivity of the excited secondary gratings can be adjusted by adjusting the amplitude of the acoustic wave (26).

Abstract: Optical waveguides are provided on a substrate, a thin film whose refractive index is optically less than the refractive indices of the optical waveguides is provided on the surface of the substrate, and a surface-acoustic-wave waveguide is arranged on the thin film so as to cross the optical waveguides in a direction oblique thereto. The optical waveguides are not directly influenced by the location of the SAW waveguide and the phase matching condition of the optical waveguides is not changed, whereby the sidelobe characteristic of an optical filter is not degraded by assigning weights to the SAW intensity.

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 substantially surrounding the at least one photonic crystal structure and 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: The present invention relates an instrument tuner possessing a fiber optic with a prewritten fiber Bragg grating. The tuner is suitable for providing more accurate instrument tuning, capable of not being subject to a tuner's subjectivity or distortions or electromagnetic interference.

Abstract: In order to identify an optical cable for optical communication from a remote place, a Sagnac interferometer including two strands of an optical fiber is formed in the optical cable, and a worker in the remote place applies a disturbance of a popping sound to an optical cable to be identified. The disturbance applied by the worker is detected and regenerated in the form of a sound. The optical cable can be easily identified by comparing the regenerated signal and the disturbed signal in the remote place to thereby prevent an incorrect optical cable from being cut. In addition, the optical cable can be more precisely identified by selecting a different light detecting frequency component in accordance with environment conditions.

Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption.