Abstract: The low Ta impurity content in pyrochlore ore makes it unnecessary to use a solvent extraction process to separate Nb from Ta. Consequently, niobium pentoxide powders using this ore can be produced at lower cost than competing mining/refining approaches, but in turn contain significant amounts of Ta impurities. SAW wafers are grown from melts produced by reacting niobium pentoxide powders containing Ta impurities at levels of 200 ppm or more by weight. Given proper amounts of starting powders, crystals can be grown with good yields and reproducible properties that satisfy typical SAW wafer specifications. The consistency across various lots of powders may be further improved by adding an appropriate amount of Ta pentoxide to the starting powders.

Abstract: A method is provided of growing crystals from compounds that melt congruently with negligible volatilization. The composition of one or more crystal samples is measured. A determination is made of a deviation of crystal composition from congruency. A determination is made of an initial melt composition and a source material composition correction relative to the deviation. Crystals are grown using the composition correction to yield reproducible material for surface acoustic substrate manufacturing.

Abstract: A method of detecting one or more scratches on a surface of a wafer made of a non-semiconductor material is provided. A UV beam is produced from a UV illumination source. The UV beam is incident on a front surface of the wafer. The UV beam being characterized that for scratches of a given material having a UV cutoff wavelength ?cutoff, over 90% of the spectral system response SSR is at wavelengths below ?cutoff?5 nm and expressed as: ? 0 ? cutoff - 5 ? nm ? SSR ? ( ? ) > 0.90 · ? 0 ? ? SSR ? ( ? ) A reflected beam of scattering of the UV beam is detected in response to scratches on a surface of the wafer. The scattering is captured.

Abstract: An acousto-optic device having at least one groove on the backside improves acoustic termination of the device. The grooves can be added early in device fabrication and are compatible with batch processing, thereby avoiding the separate device handling. Grooving can be performed on the cell, before it is mounted to a batch plate. This simplifies batch plate processing by using a backside that remains parallel to the bondface.

Abstract: A system for controlling an acousto-optic device includes an acousto-optic device having an acoustic transducer and configured to store a number of design specific parameters for a parametric tuning algorithm. the system includes a frequency synthesizer coupled to the acousto-optic device and configured to provide a radio frequency tuning signal to the acousto-optic device via the acoustic transducer. A programmable controller is coupled to the acousto-optic device and the frequency synthesizer and wherein is configured to read the design specific parameters and to receive a second number of parameters comprising one or more of environmental parameters, setup specific parameters and user specified performance parameters. the programmable controller is also configured to apply the design specific parameters and the other parameters to the design specific parametric tuning algorithm to select a radio frequency tuning signal that optimizes a user specified performance parameter.

Abstract: Methods and apparatus for preconditioning a lithium niobate or lithium tantalate crystal. At least a portion of a surface of the crystal is covered with a condensed material including one or more active chemicals. The crystal is heated in a non-oxidizing environment above an activating temperature at which the active chemicals contribute to reducing the crystal beneath the covered surface portion. The crystal is cooled from above the activating temperature to below a quenching temperature at which the active chemicals become essentially inactive for reducing the crystal.

Abstract: Methods and apparatus for preconditioning a lithium niobate or lithium tantalate crystal. At least a portion of a surface of the crystal is covered with a condensed material including one or more active chemicals. The crystal is heated in a non-oxidizing environment above an activating temperature at which the active chemicals contribute to reducing the crystal beneath the covered surface portion. The crystal is cooled from above the activating temperature to below a quenching temperature at which the active chemicals become essentially inactive for reducing the crystal.

Abstract: AOTF controller that monitors output power of a plurality of wavelengths of an AOTF and scans the frequency of corresponding RF input signals to an AOTF acoustic transducer and searches for the RF frequency corresponding to each desired wavelength that provides maximum optical output for each wavelength. The controller includes a plurality of sensor inputs for monitoring the power of each wavelength output from the AOTF, and alternatively, also monitors other AOTF parameters such as temperature and/or reads AOTF identification performance data that can be stored in a EPROM on a AOTF housing. The controller includes facility for input of modulation data, and in response to the data modulates the corresponding wavelength parameter such as power. A USB bus is provided for input of programming to the controller, and for output of performance data from the controller.

Abstract: Crystals of lithium niobate and lithium tantalate are preconditioned to intentionally increase their electrical conductivity, thus providing crystals with an increased ability to reduce surface charging. Reducing surface charging reduces the risk that the crystals may catastrophically discharge, and adversely affect the performance of devices in which the crystal is incorporated.

Abstract: A plurality of optic modulators implemented using segmented electrodes and nonparallel waveguide structures are cascaded using optical couplers to provide a linearization of the overall electro-optic transfer function. Each of the optical modulators which are coupled in cascade have an electrode structure which is divided into a plurality of relatively small segments. The segments are connected via bond wires and transmission lines on an adjoining microwave circuit board. Each of the optical modulators includes a pair of waveguides which are sloped so as to result in a nonparallel waveguide structure which reduces acoustic effects, e.g., ripple. By using a plurality of small segments to implement the electrode structure a high degree of sensitivity is achieved as compared to when a single lengthy electrode structure is used. The combination of the non-parallel waveguides and a segmented electrode provides for a relatively large flat frequency response, e.g., in excess of 1 GHz.

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 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 optical modulator having an electrode structure which is divided into a plurality of relatively small segments is described. The segments are connected via bond wires and transmission lines on an adjoining microwave circuit board. The optical modulator includes a pair of waveguides which are sloped so as to result in a nonparallel waveguide structure which reduces acoustic effects, e.g., ripple. By using a plurality of small segments to implement the electrode structure a high degree of sensitivity is achieved as compared to when a single lengthy electrode structure is used. The combination of the non-parallel waveguides and a segmented electrode provides for a relatively large flat frequency response, e.g., in excess of 1 GHz. The electrode structure is also designed to minimize the effective capacitance of the electrode structure to thereby broaden the bandwidth of the optic modulator of the present invention as compared to devices using solid electrodes.

Abstract: A plurality of optic modulators implemented using segmented electrodes and nonparallel waveguide structures are cascaded using optical couplers to provide a linearization of the overall electro-optic transfer function. Each of the optical modulators which are coupled in cascade have an electrode structure which is divided into a plurality of relatively small segments. The segments are connected via bond wires and transmission lines on an adjoining microwave circuit board. Each of the optical modulators includes a pair of waveguides which are sloped so as to result in a nonparallel waveguide structure which reduces acoustic effects, e.g., ripple. By using a plurality of small segments to implement the electrode structure a high degree of sensitivity is achieved as compared to when a single lengthy electrode structure is used. The combination of the non-parallel waveguides and a segmented electrode provides for a relatively large flat frequency response, e.g., in excess of 1 GHz.

Abstract: A method of growing optical quality beta barium borate; crystals from a pure NaCl fluxed melt. The method comprises maintaining particular thermal field conditions throughout the melt and slowly cooling the melt to cause beta barium borate to crystallize from the melt. The rate of cooling may be at a rate of not greater than 3.degree. C. per day. The method may utilize a seed crystal, suspended into the melt, so that the beta barium borate may crystallize on the seed crystal.

Abstract: A new compositional relationship in the starting charge of a crystal growth station (FIG. 1 ) provides homogeneous monocrystalline lithium niobate. A new measurement system (FIG. 2 ) provides Curie point values of significantly greater accuracy then that of conventional measurements. Careful control of the starting charge composition for crystal growth and effective utilization of the measurement system enable the determination of the compositional range of starting charges for producing congruent crystalline production. The composition corresponds to a mol percentage of 48.35.+-..01 to 48.40.+-..01 of Li.sub.2 O and the remainder Nb2.sub.O 5 for producing homogeneous crystal whose solidification fraction of the molten charge exceeds that which was heretofore achievable.

Abstract: An optical element composed of a single crystal consisting essentially of potassium titanyl phosphate, which is represented by the formula KTiOPO.sub.4 and which is doped with cerium. The optical element has a high optical transmissivity property for radiation from the near-UV to the mid-infrared spectral regions.

Abstract: A technique of providing numerous distinct conductive patterns on a piezoelectric substrate is accomplished using only two masking apparatus. One masking apparatus defines a common portion or structure for each of the patterns. The second masking apparatus defines numerous distinct patterns, each corresponding to a different alignment position with respect to the common structure already formed on the substrate. One application for this technique is in economic production of coded SAW devices which may serve as coding or decoding devices, filters, or correlators, each of the SAW devices having a different individual code.

Abstract: A SAW device using a first reflector (13) and a second reflector (14) is arranged to provide compensation for temperature effects. The temperature effects are due to the anisotropic characteristics of piezoelectric material commonly used as the substrate and wave medium for the acoustic waves in the SAW devices. These materials typically exhibit a temperature dependent, preferential direction of transmission which if not compensated results in a temperature dependent signal attenuation. An additional technique using a non-reflective portion 22 offsets non-uniformity which occurs in the amplitude distribution of the reflected acoustic wave. Each reflector (13 and 14) may include its respective non-reflective portion (A.sub.1 and A.sub.2).