Abstract: An apparatus and method for controlling an image recording device. The apparatus includes an acousto-optic deflector that deflects a beam of light so as to write a sub-scan comprising a predetermined number of picture elements. The image recording device is arranged to write a plurality of sub-scans side by side in a substantially contiguous manner. The apparatus also includes a component that commences sub-scans, a start of sub-scan detector that detects when the light beam is directed towards a start of sub-scan position, and an end of sub-scan detector that detects when the beam of light is directed towards an end of sub-scan position. A timing logic controller generates a start reference signal representing a desired position for the start of a sub-scan. A controller compares an output of the start of sub-scan detector with respect to the start reference signal.

Abstract: An acousto-optic modulator comprised of an acousto-optic element coated with an anti-reflection layer, and a method of manufacturing the same, are provided. The acousto-optic modulator includes an anti-reflection layer, comprised of at least two coating layers having different refractive indices, formed on the light incident/emitting surface of an ultrasonic medium for modulating a light beam incident from an optical source.

Abstract: A programmable acoustooptic device including an elastooptic medium configured to receive an input optical pulse and an acoustic wave; an acoustic transducer configured to generate the acoustic wave in the elastooptic medium along a defined direction; and a programmable circuit coupled to the acoustic transducer and configured to program at least one of a frequency modulation and phase modulation of the acoustic wave, whereby the acoustic transducer generates a modulated acoustic wave, wherein an output optical pulse is generated and is a convolution of the input optical pulse with the modulated acoustic signal.

Abstract: An optoacoustic modulator contains first and second optoacoustic media, to which first and second piezoelectric vibrators are attached respectively. Herein, both of the first and second optoacoustic media are designed in same measurements, wherein they are arranged in series along an optical axis of a light signal in such a way that crystal orientation of the first optoacoustic media differs from crystal orientation of the second optoacoustic media with an angle of inclination of 90.degree.. In addition, the first piezoelectric vibrator is attached to a first surface of the first optoacoustic media which is placed in parallel with the optical axis of the light signal, while the second piezoelectric vibrator is attached to a second surface of the second optoacoustic media which is placed in parallel with the optical axis of the light signal, wherein the first surface is directed perpendicular to the second surface.

Abstract: A solid state acoustic travelling wave lens comprises a thin core layer of acoustic and light transmissive material, such as crystalline quartz, compression-bonded between a pair of outer or cladding layers, such as fused silica, having an acoustic velocity that is only slightly higher than (e.g., less than five percent of) that of the core material. The acoustic mode field characteristic of the weakly guiding device contains no spatial variations caused by Fresnel diffraction in an unguided wave device. In a second embodiment, shear stress coupling between the core and cladding layers is inhibited by interposing very thin liquid boundary layers between the core layer and the cladding layers. Such thin liquid boundary layers, which are relatively more compressible than the core and cladding material, allow longitudinal waves to be transmitted across the core/cladding boundary (through the liquid), but prevent transmission of shear waves therebetween.

Abstract: A laser beam intensity modulation system has a variable delay circuit that is used to control the relative delay in the delivery of a video signal between two cascaded AOM's. This delay circuit is controlled by a delay controller that monitors the intensity modulation of the laser beam to provide feedback control. This system maximizes the rise and fall times of the beam to generate precise beam modulation required for high speed image setters.

Abstract: Light from a collimated light source which is incident on a birefringent detector at a predetermined optimum angle interacts with the birefringent detector and is viewed by an imaging transducer in order to produce an image which shows changes in the birefringence of the birefringent detector caused by acoustic energy which has interacted with an object, the image thus showing heterogeneities in the object.

Abstract: A telemetry system for receiving data from large arrays of sensors, in which the sensors are located in an unprotected environment, is implemented using fiber optic components. Laser sources, located in a protected environment, transmit light through the boundary separating the protected environment from the unprotected one. The light is then split into a number of beams and fed to electro-optical modulators, where it is modulated in response to electrical signals received from the sensors. The modulated light signals are then wavelength-division multiplexed and transmitted back through the environment boundary, where they are amplified, demultiplexed and converted to electrical signals. Multiplexing reduces the number of boundary penetrations, and the use of highly stable electro-optical modulators eliminates the need for signal conditioning electronics at each sensor.

Abstract: An acoustic traveling wave lens structure for an acousto-optic scanner comprises a confined height fluid-containing channel, upon which a scanned optical beam to be modulated by a acoustic traveling wave is incident. The channel is bounded by spaced-apart walls that extend between a first end of the scanner channel, to which an acoustic transducer is coupled, and a second end of the channel that terminates an acoustic traveling wave launched from the acoustic transducer. The thickness of the channel is linearly tapered from the first end to the second end, so as to maintain a constant acoustic power density. To compensate for the attenuation in acoustic power through the water medium, the waveguide may be heated, to maintain the temperature of the liquid medium (water) within the waveguide channel within a prescribed temperature range over which the acoustic velocity remains substantially constant or undergoes a relatively small variation.

Abstract: A polarization independent acousto-optic tunable filter (PIAOTF) used for multiwavelength switching and routing in wavelength division multiplexing (WDM) networks. In the PIAOTF an incident unpolarized light beam is divided to propagate and to be diffracted along two polarization division branches. By using polarization converters and equal optical paths for the two polarization division channels, a PIAOTF is created which minimizes polarization dependent loss and polarization mode dispersion. Furthermore, a preferred embodiment of the AOTF using an elongated acousto-optic interaction medium is described that provides the additional advantages of narrow bandwidth, lower drive power and easier alignment.

Abstract: In a non-collinear type acousto-optic tunable filter, a source light beam is made off-perpendicularly incident on a crystal body, so that the cross section of the source light beam is narrowed within the crystal body. As a result, the receiving angular aperture becomes large to increase the amount of light collected into the crystal body. Consequently, highly accurate spectrometry can be performed even if the intensity of the source light beam is low. Further, the non-diffraction part of the crystal body can be eliminated by the off-perpendicular incidence of the source light beam, so that the sufficient diffraction length of acoustic and optic waves can be obtained.

Abstract: There are proposed light beam scanning method and device for scanning with plural light beams split by using a multi-frequency acousto-optic device (AOM). By remarkably increasing the number of light beams, an image is recorded at a higher speed. Plural incident light beams are split in the subsidiary scanning direction by different multi-frequency acousto-optic devices. The split light beams are displaced so as not to overlap one another in the subsidiary scanning direction, while respective sets of light beams split by the acousto-optic devices are deviated in a main scanning direction, for scanning. The deviation in the main scanning direction is compensated with a clock timing of an image signal. The light beams split by the AOMs may be alternately positioned in the subsidiary scanning direction. Alternatively, a set of light beams split by one AOM may be adjacent to a set of light beams split by another AOM in the subsidiary scanning direction.

Abstract: The object of the present invention is to present an acoustooptical modulator without ripples in its wavelength loss characteristics. In order to achieve this objective, the present invention provides an acoustooptical body 8 having a piezoelectric vibrator supplying, for example, ultrasonic vibration, to modulate the incident optical signal, an acoustooptical medium rotated 90.degree. on the crystal axis of the acoustooptical medium upon which the optical signal emitted from acoustooptical medium is incident, and eliminates the polarization mode scattering caused the birefringence of both acoustooptical medium and acoustooptical medium.

Abstract: In a non-collinear type acousto-optic tunable filter, the incident angle of a source light beam L.sub.1 radiated from a light source 6 onto an acoustic medium 1 is set at an equivalence incident angle for which the wavelength .lambda..sub.i of the diffracted ordinary ray L.sub.3 and the wavelength .lambda..sub.i ' of the diffracted extraordinary ray L.sub.4 become approximately identical. Further, the diffracted ordinary ray L.sub.3 and the diffracted extraordinary ray L.sub.4 of the approximately identical wavelength are superposed, and the intensity of the superposed ray is detected. Consequently, spectrometry is performed based on the superposed diffracted ray having twice the intensity and a very sharp waveform, so that accurate spectroscopy can be made possible even if the intensity of the source light beam is low.

Abstract: An electro-acoustic transducer is attached to a block of optical material, and forms an acoustic standing wave in the block; the acoustic standing wave periodically changes the refractive index of the optical material, and forms high refractive index portions alternated with low refractive index portions; and the high refractive index portions serve as optical wave guides, and the electro-acoustic transducer easily produces the optical wave guide in the block.

Abstract: In order to increase the available signal processing bandwidth of an acousto-optic coherent channelizer, the optical beam spot-shaping and projection components of the channelizer are configured to project M reference beam spots upon each photodetector of the channelizer's photodetector array. The parameters of the reference Bragg cell, reference signal R(t), and Fourier optics components are such that they project M reference beam spots upon each photodetector of the channelizer's photodetector array, where M is the desired system bandwidth multiplication factor. No change to the configuration of the photodetector array or its associated post-detection signal processing electronics is required.

Abstract: This invention relates to an acousto-optic time-integrating correlator for rocessing broadband Doppler-shifted signals. The present invention uses a conical lens telescope to compensate, in one dimension, for the differences in the absolute values of Doppler shift occurring in broadband signals. A laser light beam is expanded to a sheet beam using a conventional beam expander. The sheet beam is split and redirected using a modified Koster's prism. The two sheet beams are them directed toward a SAW device. The SAW device contains two tilted transducers. The inputs to the SAW device are counterpropagating A Doppler-shifted sheet beam and an undiffracted sheet beam are processed by respective conical lens telescopes. The outputs of the conical lens telescopes are combined with associated unprocessed sheet beams and combined by respective modified Koster's prisms and imaged onto respective two-dimensional photodetectors. The output of one photodetector is subtracted from the other to reduce offsets.

Abstract: A passive acousto-optic modulator for the modulation of a light beam as a function of a variation in air pressure comprising a beam splitter arranged relative to the beam so as to produce a signal beam and reference beam, the beam splitter ideally comprising a flat interface located between two optically transparent mediums such as the end of an optic fiber located within air, the interface being arranged relative to the light modulator such that when the light beam travels through the interface, some of the light beam is able to pass through the interface to form the signal beam, the rest of the light beam being reflected back off the interface to form the reflected reference beam; a light modulator which modulates the signal beam, the light modulator comprising an approximately flat optically reflective surface capable of movement, the reflective surface being located in a position which, at rest is a predetermined distance from the beam splitter and is approximately parallel to and facing the beam splitter

Abstract: An acousto-optic tunable filter based on isotropic acousto-optic diffraction using phased array transducers. The isotropic AOTF provides the advantages of narrow optical passband, low acoustic frequencies, and insensitivity to the input optical polarization. Preferred embodiments of the isotropic AOTFs are described for optimized spectral resolution and diffraction efficiency.

Abstract: An xyz coordinate system is determined so that a z-axis may coincide with an incident direction of an incident light, an x-axis may coincide with a polarizing direction of the incident light and a y-axis may be defined as the right-handed system from the z-axis and x-axis. An acousto-optic element is rotated around the z-axis, around the axis in a direction of propagation of an ultrasonic wave and around an axis B perpendicular to a plane formed by the z-axis and the direction of propagation of the ultrasonic wave, so that the attitude of the acousto-optic element to the incident light is adjusted.

Abstract: An acousto-optic modulator having an ultrasonic medium for controlling light from a light source by diffracting the light and a transducer portion having electrodes for generating an acoustic wave in the ultrasonic medium, wherein the transducer portion includes two transducers each having an electrode. The AOM is provided with two electrodes by using two transducers, thereby facilitating impedance matching with a driver. The two transducers may be installed so that their polarization directions are opposite to each other, thereby obtaining maximum power transfer to the ultrasonic medium.

Abstract: A multi-beam emitting device which splits a light beam emitted from a light source into a plurality of beams with a beam splitter to emit a plurality of beams. As the beam splitter, an optical waveguide type acoustooptic element or the like is used. A multi-beam emitting device according to the present invention has a beam splitter which drives an acoustooptic element with a plurality of electric signals with different frequencies applied thereto so as to deflect a light beam emitted from a light source and split the light beam into a plurality of beams, a signal generator which generates the electric signals with different frequencies which are used for the drive of the acoustooptic element, a modulating circuit which turns on and off the electric signals generated by the signal generater individually based on a data signal, an intensity control circuit which controls the light source to change the intensity of the light beam emitted therefrom.

Abstract: An optical assembly comprising an optical element and a transducer is suspended within an enclosure so that the optical assembly is free to vibrate within the enclosure. In one embodiment, the mechanisms for suspending the assembly do away with any elastomeric material that would cause outgassing in applications where the photoelastic modulator is used in a high vacuum environment. The suspension system also increases the efficiency of the system.

Abstract: An optical switch is formed by: at least one switch driving circuit for generating ultrasonic waves; at least one electric acousto-optic element forming at least one diffraction grating therein upon being applied with the ultrasonic waves generated by the switch driving circuit; at least one polarization rotator for rotating a polarization plane of a first primary diffracted light produced by the diffraction grating, by 90.degree.

Abstract: The present invention provides a method of ameliorating the effects of misalignment between modulator, and a system using the same. The individual modulator elements are positioned such that a portion of the image produced is generated by both elements. The contribution to the combined output made by each element varies across the overlapped region, with each element making a small contribution to the pixels in the overlapped region at one end and a large contribution to pixels in the overlapped region at the other end. Because the overlapping output regions of the modulators collectively form a portion of the image, any alignment error is effectively spread over the entire overlapped region and is much less noticeable.

Abstract: A apparatus and method for coherently stretching or compressing signals of nterest, i.e. without loss of information. A first, or tapping, Bragg cell has an acoustic signal launched in it which is modulated onto a laser carrier. The signal of interest is launched into a second, or signal, Bragg cell, and is similarly modulated onto the carrier exiting the first Bragg cell. Upon demodulation, the resultant signal, is the convolution of the two acoustic signals in the respective Bragg cells, but whose duration is either stretched or compressed according to the relative velocity between the acoustic signals in the two Bragg cells, and by the magnification of optics between the two cells. If the signal in the first Bragg cell is of such a short duration that it is effectively an impulse, the resultant signal is a coherently stretched or compressed replica of the signal launched into the second Bragg cell, i.e. the signal of interest.

Abstract: An imaging system comprises an acousto-optic tunable filter for receiving light at an input end thereof and outputting light at an output end thereof. A control circuit is provided for tuning the filter. A prism is responsive to the light output by the tunable filter. The prism is oriented at an angle with respect to the filter to compensate for dispersion of the output light caused by the tunable filter.

Abstract: Combining a tristimulus filter, two lenses, and a crystalline colloidal ay filter in an arrangement resulting in a visible optical limiter without substantial color distortion that can be used for eye or sensor protection. Only three nonlinear colloidal arrays are needed to Bragg reflect over the pass bands of the tristimulus filter. The nonlinear colloidal array is arranged so that the band reflected (at the least) completely overlaps the pass band of the tristimulus filter.

Abstract: A technique of stabilizing the output of an acoustooptic modulator. A laser passes a light beam through the acoustooptic modulator. A driver circuit connects to a drive electrode of the acoustooptic modulator. RF generators deliver drive power at a first carrier frequency and compensation power at second and third carrier frequencies, one higher and the other lower than the first carrier frequency. The driver circuit modulates the drive power and the compensation power such that compensating acoustic energy induced in the acoustooptic modulator complements drive acoustic energy, and the spatial content of the drive acoustic energy. The combined drive power and the complementing compensating power maintain the spatial thermal energy distribution inside the acoustooptic modulator substantially constant. Consequently, beam steering and thermal ellipticity are stabilized and remain substantially constant throughout the operating range of the modulator.

Abstract: A device for converting the frequency of an optical signal to form a frequency comb having a plurality of frequency spaced optical carriers. In one embodiment, a magnetooptic frequency conversion device is disclosed wherein the frequency of the optical signal is shifted by the frequency of an AC signal generating a magnetic field through a crystal. In another embodiment, acoustooptic scattering is used wherein an acoustic wave is provided to a waveguide which receives an optical signal so that the frequency of the optical signal is shifted by the frequency of the acoustic wave. In yet another embodiment, a single sideband modulator is used to shift the frequency of an optical signal.

Abstract: A system for electronically powering an acoustooptic device. A radio-frequency (RF) generator supplies RF drive power at a drive carrier frequency. A signal source delivers a modulating signal. An RF modulator modulates the RF drive power with the modulating signal. Two compensating RF power generators supply high-frequency and low-frequency compensating power at frequencies greater than and less than the drive carrier frequency. Operational amplifiers and modulators modulate the compensating power with signals derived from the signal source such that the modulated compensating power is the complement of the modulated RF drive power. A summer combines the modulated RF drive power and compensating power to drive the acoustooptic device such that the spatial thermal energy distribution inside the acoustooptic device remains substantially constant.

Abstract: An acousto-optic deflector device having a piezoelectric thin film and IDT formed on a substrate for deflecting a light by causing an SAW generated at an SAW generator region to interact with the light at a light waveguide region. The piezoelectric thin film is constructed of a first piezoelectric thin film having a relatively high resistance and a high piezoelectricity in the SAW generator region, and a second piezoelectric thin film having a smaller light propagation loss than the first piezoelectric thin film 3a in the light waveguide region.

Abstract: An apparatus for, and method of, decreasing a temporal duration of an optical input pulse having an input power spectrum associated therewith, the apparatus and method operative on at least unchirped optical input pulses. The apparatus comprises: (1) a zero-dispersion pulse shaper for receiving the optical input pulse and spectrally spreading the input pulse to produce a spectrally-spread pulse and (2) a modulator array interposed within the zero-dispersion pulse shaper for receiving the spectrally-spread pulse and selectively attenuating a portion of the power spectrum of the spectrally-spread pulse by a predetermined amount to produce a selectively-attenuated spectrally-spread pulse, the zero-dispersion pulse shaper focusing and recombining the selectively-attenuated spectrally-spread pulse to produce an output pulse having a broader power spectrum than the input pulse, the output pulse further having a temporal duration less than the input pulse, regardless of whether the input pulse is chirped.

Abstract: A high definition image projector is provided for modulating light using an acousto-optic tunable filter according to image signals and projecting the modulated light on a screen. An image is obtained by modulating a light beam by pixel units according to the image to be displayed and directly projecting the modulated light beam on the screen in corresponding pixel units. High quality images can thus be displayed on a large screen. By adopting a high-output light source, a high luminance image can be obtained.

Abstract: An acoustooptic device includes a Y-cut and Z-propagation LiNbO.sub.3 substrate or 128.degree.-rotating Y-plane LiNbO.sub.3 substrate, an optical waveguide layer which is formed on at least a part of the LiNbO.sub.3 substrate and has a higher light refractive index than the LiNbO.sub.3 substrate, an interdigital electrode which is formed on the LiNbO.sub.3 substrate and generates Rayleigh waves, and a dielectric thin film layer formed on the interdigital electrode.

Abstract: An acousto-optical filter (AOTF) having reduced sidelobes. The AOTF is fabricated with a waveguide formed on a substrate along an optical axis. An incoming beam of light is coupled into the waveguide. An acoustic wave beam is induced by an interdigitated transducer. The acoustic wave beam follows an acoustic wave beam axis which crosses the optical axis. The transducer is driven by an externally-generated electric signal. The frequency of the acoustic wave beam is determined by the frequency of the electric signal. The acoustic wave beam induces a diffraction grating in the waveguide as the acoustic wave beam crosses the optical axis, and this in turn diffracts the beam of light. The grating couples the transverse electric and transverse magnetic polarization modes of the light, but only within a narrow band of optical wavelengths. The cross-section of the intensity of the acoustic wave beam can be tapered to further reduce the sidelobes of the passband defined by the frequency of surface acoustic wave beam.

Abstract: Modulated interference effects arising when laser beams are modulated by photoelastic modulators are substantially eliminated by methods and apparatus that extract from the detected beam the modulated, interfering light that emanates from the optical element of the modulator.

Abstract: A series of taps are created within an acousto-optic cell by imaging an array of LEDs within the cell. The illuminated tap regions are selectively changed by energizing selected LEDs. The electrical input signal produces a travelling acoustic wave within the cell and when the wave crosses illuminated tap regions, electrical output signals are produced having delays proportional to the positions of illuminated LEDs in the array. The magnitude of the output signal is proportional to the LED light intensity which is varied to produce a weighted output signal.

Abstract: A signal filter, and method of signal filtering, in which an optical signal s spatially dispersed according to frequency, and undesired frequencies blocked out. In an embodiment, a Bragg cell receives a (typically microwave) signal, and transduces it to an acoustic signal. A light source, e.g. a laser diode, directs light through the acoustic signal in a known manner so as to produce an optical output which is spatially dispersed according to frequency. A programmable spatial light modulator blocks out unwanted frequency components. Upon removal of the optical carrier, e.g. by heterodyning the spatial light modulator's output with a reference signal from the light source, the components can be recombined into a resultant filtered signal. The invention can be used as a repeater, a military electronic countermeasure, in environments which have large amounts of electromagnetic clutter but in which one does not want the clutter repeated.

Abstract: A phase shift illuminator (700) is comprised of a light source (704) and a phase modulator (716), typically a flexure beam micromirror array, which transversely modulates the incident light beam. When a flexure beam micromirror array is used as the phase modulator (716) a polarizing beam splitter (712) and a quarter-wave plate (714) are used to separate the incident and reflected light beams. The phase modulated light beam (720) from the optical illuminator may be used in optical lithography by passing the light beam through a lithography mask (724), typically after the light beam is phase modulated, and focusing the light beam onto a target wafer (726).

Abstract: The frequency components of an input pulse are dispersed into divergent respective rays that are applied to an acousto-optic modulator after being collimated. The amplitude of each frequency component emerging from the modulator is determined by the amplitude and phase of a grating formed therein by modulated radio frequency wave applied to it. The parallel rays emerging from the modulator are focussed onto a device for forming an output pulse.

Abstract: In an external modulator for optical communication, a piezoelectric element section is formed by laminating a lower electrode, a piezoelectric thin film and an upper electrode in this order on one surface of a substantially flat substrate which has substantially the same acoustic impedance as the clad layer of a single mode optical fiber to be disposed on the substrate. At least one single mode optical fiber is disposed on the other surface of the substrate on the upper electrode, and the single mode optical fiber is at least partly coated with a material having an acoustic impedance substantially equal to that of the clad layer in a place in which the single mode optical fiber is disposed.

Abstract: Acousto-optical devices utilize crystals of a novel material thallium arsenic sulfide (Tl.sub.3 AsS.sub.3) grown from a melt. A Tl.sub.3 AsS.sub.3 crystal is cut and parallel faces are prepared and polished. A piezoelectric transducer connected to an RF generator is placed on the acoustic face to generate sound waves. The light is directed through the optical face of the crystal and interacts with the acoustic waves. These devices may be used in signal processing, spectrum analyzing, spectroscopic, liquid analyzing and spectral imaging systems.

Abstract: A laser scanner is disclosed, in which M, the lateral magnification obtained from the first and the second optical members, V.sub.1, the scanning velocity of the scanning beam on the beam receiving surface and V.sub.s, the velocity of the acoustic wave inside the acoustic beam modulator are substantially related by M=-V.sub.1 /V.sub.

Abstract: Acousto-optic polarization converters can be used as the primary optical components in a multi-channel wavelength-routing switch (101). Switching efficiency is decreased and the polarization converted wavelength channels are shifted towards each other, however, when closely neighboring channels are selected simultaneously. This degradation has serious consequences for many applications of the acousto-optic polarization converter. By applying counterpropagating acoustic waves from opposite ends of a converter (400) and using an acoustic absorber (417) to separate the left and right sides of the converter at a defined coupler crossover length, L.sub.x, this deleterious degradation is substantially reduced.

Abstract: Devices for controlling high frequency signals such as optic or electric signals are disclosed which utilize guided and/or reflected surface acoustic waves. The devices preferably use crystalline substrates modified (e.g., by ion exchange to increase mass density) to contain acoustic reflectors and/or continuous acoustic waveguiding channels (optionally, in combination with optical features such as optical waveguiding channels) and interdigital transducers deposited thereon to provide frequency generation (and reception where high frequency electrical signals are controlled). The preferred crystal substrates are of a material having a piezoelectric-elastic dielectric matrix capable of the generation of acoustic waves, such as MTiOXO.sub.4 (where M is K, Rb, Tl, and/or NH.sub.4 and X is P and/or As) having mm2 symmetry.

Abstract: An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with an RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

Abstract: An acousto-optic tunable filter (100) is provided with an acousto-optic interaction profile that results in a frequency response with near-ideal bandpass filter characteristics of near-unity transmission inside the passband and near-zero transmission outside the passband. The acousto-optic interaction profile which results in this frequency response has a phase polarity which alternates and is damped, i.e. the acousto-optic interaction profile has a damped oscillating shape. The physical structure to implement this filter comprises a pair of acoustical waveguides (110, 112) which taper toward each other at the beginning of the profile and then are spaced apart by a constant distance. A damping layer (132) or other damping structure is provided to achieve the damping characteristics of the profile.

Abstract: Light from a laser (10) is divided by a beam splitter (12) to provide signal (15) and reference (14) channels. The signal channel light is expanded (11) to illuminate an acousto-optic (AO) device (13). This leads to a spatial distribution of Doppler shifted frequencies. This spatial distribution then illuminates a spatial light modulator (SLM) (19) such that a number of parallel and discrete optical channels (112) emerge. In a local area network (LAN) the optical signal channels are coupled into a single mode optical fibre (22) and then heterodont to the reference laser light from a further optical fibre (23) in an optical coupler (25). In a receiver the modulated light is detected (32) and the detected signal connected to the transducer of an AO device (35). The AO device (35) is illuminated by a receiver laser light (36) and the emerging modulated light is incident on a focal plane detector array (39) where each detector (310) then receives light corresponding to each of the transmitted channels (311).

Abstract: Devices for deflecting an optical beam under the action of an ultrasonic beam propagating in a block of active acousto-optical material and operating under Bragg tangential conditions, with the acousto-optical interaction being anisotropic. The devices also include entry and exit faces into this material blocks which are inclined at angles .alpha. and .beta. such that the incoming beam and the emerging beam after the interaction are significantly parallel, keeping operation under Bragg tangential conditions. The devices can also be used to make a spectrum analyzer with a very large number of points and very high dynamics.