Efficiency SAW Research Articles

Control System of Micro Droplet using Microdispenser Based on Solenoid Valve and its Application for Highly Efficient SAW Atomizer

Control System of Micro Droplet using Microdispenser Based on Solenoid Valve and its Application for Highly Efficient SAW Atomizer

Near-field elastomeric mask photolithography fabrication of high-frequencysurface acoustic wave transducers

Optical lithography is the method of choice for mass production of electronic aswell as acoustic devices. Cost issues, in particular, make it superior over slow buthigh-resolution methods, such as electron beam lithography. Also, itsapplicability for nonconductive substrates is an important feature for acousticdevice fabrication on ceramics. In order to be able to continue the use ofdiffraction-limited optical lithography, new schemes have been developedthat enhance the resolution. Rather complex phase-shifting masks, forinstance, alter both the amplitude and the phase of the exposing light andlead to higher resolution. However, by using an elastomeric phase maskderived from a photoresist master (made by conventional photolithography),features as small as 90 nm have been demonstrated. We report on theapplication of the near-field phase shift technique for the fabrication ofsurface acoustic wave (SAW) devices. This technique is best suited for thefabrication of narrow electrode gap SAW devices that are designed forthe efficient SAW excitation at higher harmonics. The combination ofnear-field phase shift lithography with narrow-gap SAW designs thus opensup a way for simple and low-cost SAW devices operating above 5 GHz.

Studies on acousto-optical interaction in epitaxial thin film heterostructures

Thin film epitaxial heterostructures consisting of and /Si have been studied theoretically with interdigital transducer (IDT) electrodes at various locations. The thickness of each individual layer has been optimized for achieving an efficient SAW performance with a high electromechanical coupling coefficient. The structural feasibility and practical implications of various device configurations for an acousto-optical device are discussed. The introduction of a thin non-piezoelectric over-layer onto a piezoelectric film is found to enhance the electromechanical coupling coefficient . In a symmetrical /IDT/ waveguide structure the maximum value of is found to increase from 2.438 to 9.23% for a variation in the thickness of the over-layer in the range 0-0.12. Symmetrical and asymmetrical waveguide structures formed with and thin films in combination have been examined and a symmetrical waveguide structure (/IDT//Si) is found to exhibit a high acousto-optical figure of merit and % for a device operating with the fundamental mode at wavelength m.

High transfer-efficiency microsurface acoustic wave directional couplers

Surface acoustic waves (SAWS) directional couplers have long been known in both microwave and integrated acoustic applications. Such couplers, when both channels are of different widths and different dispersion characteristics, may also be used as electronic filters. SAW directional couplers are ideal for inclusion in acoustical signal processing devices, as modulators or switches. This article represents formulation and physical properties of advanced high transfer efficiency SAW directional couplers, using the coupled mode theory. One kind of directional coupler is especially considered and discussed in detail. The obtained coupling parameters are applicable to any guided modes in parallel waveguides of the same cross section, similar to 1/v index of refractive and identical shapes. Coupling constants and physical parameters for the coupled acoustic modes, computed according to this theory, are shown and seem to agree very well with experimental data.

Efficient SAW convolver with 30 μs integration time

A SAW convolver is described with input bandwidth 20 MHz and integration time in excess of 30 μs. It displays a high convolution efficiency (≃ −63 dBm) and self convolution suppression exceeding 40 dB.