This article describes a new transverse edge structure with double busbar for surface acoustic wave (SAW) devices employing a 42°YX-lithium tantalate thin plate such as incredible high-performance (I.H.P.) SAW. This design offers good energy confinement and scattering loss suppression for a wide frequency range. First, preexisting transverse edge designs are reviewed, and their difficulties are pointed out using the dispersion relation for lateral SAW propagation. Then, numerical simulations are performed using the periodic 3-D finite-element method (FEM) powered by the hierarchical cascading technique, and effectiveness of the proposed structure is revealed. In addition, we also provide a possible solution to expand the frequency range giving well energy confinement and demonstrate effectiveness of manipulating the SAW slowness curve shape for transverse mode suppression.

Low-loss photonic crystal (PC) mirrors exhibit positive and negative Goos–Hänchen shift (GHS) due to the strong angular and wavelength dependencies of their reflected phase. This Letter demonstrates the existence of large positive and negative GHS in PC mirrors through theoretical, numerical, and experimental approaches. A simple algebraic relation shows that positive effective thickness yields positive (negative) GHS for resonances that blue (red) shift with angle, while the opposite is true for interfaces with negative effective thickness. Spatiotemporal coupled-mode theory demonstrates the above relation for simple systems with one or two resonance modes, and it also shows the existence of both positive and negative GHS. These effects are numerically and experimentally verified in complex PCs with several resonance modes.

This paper compares three different piston mode designs for temperature-compensated surface acoustic wave (TC-SAW) resonators using SiO ₂ /LiNbO ₃ structure. It was shown that in rough approximation, phase shift given by extra elements for the piston mode operation is determined by the total mass of extra elements and SiO ₂ which overlaid on piston region. The hammer head design without additional metal layers does not work properly due to the weaker impact of the extra elements when the SiO ₂ layer is thick. On the other hand, piston mode designs using metal dots or stripes are effective to suppress the transverse mode resonances even when the SiO ₂ layer is thick. Although larger metal thickness is preferable for the wideband operation, it also makes the split of main resonance. Thus, the optimal metal thickness can be found from this trade-off, and then the optimal metal width can be found to achieve good transverse mode suppression.

This paper describes the design, characterization, and testing of a compact hydrophone capable of measuring acoustic signals from cardiomyocytes. Our hydrophone consists of a nanofabricated photonic-crystal diaphragm externally-mounted to the facet of an optical fiber to form a pressure-sensitive Fabry-Pérot cavity. Our hydrophone can operate in small liquid volumes less than 5 mm deep and incorporates a microchannel to vent air during immersion. The venting channel is designed to optimize bandwidth and sensitivity. Modeling and experimental results in water show a bandwidth from 50 Hz to 18 kHz and a minimum detectable pressure of 3 μPa/ √{Hz}. We demonstrate the sensitivity to simulated bio-acoustic sources with nanometer-scale displacements.

This paper discusses combination of tetragonal crystals with LiTaO ₃ (LT) thin plate for complete transverse resonance suppression of surface acoustic wave devices without k ² deterioration by manipulating the slowness shape. Besides, better lateral energy confinement is achieved as well by the use of double busbar structure. First, the mechanism of slowness shape manipulation by combining tetragonal crystals is studied. By comparison, YZ-lithium tetraborate (LBO) shows better performance than 69°Y90°X quartz. Then numerical simulations are carried out using periodic three-dimensional finite method assisted by hierarchical cascading technique, and the effectiveness of transverse mode suppression by flattening the slowness shape is revealed. And the possibility to realize temperature compensation is discussed owing to the unique material property of LBO. Moreover, the capability of other tetragonal crystals for slowness manipulation are compared, and LBO is the best choice among these tetragonal crystals.

This paper discusses the applicability of dielectric materials with high acoustic impedance Z _a for use in A ₁ Lamb mode solidly mounted resonator (SMR) with large electromechanical coupling coefficient k ² . The study first shows that the use of metal as a reflector creates parasitic capacitance C _p , which reduces k ² significantly. Then, A ₁ Lamb mode SMRs are designed using HfN, HfO ₂ , WN, WO ₃ etc., and achievable performances are compared. When either HfN, HfO ₂ , WN, or WO ₃ is employed, relative large k ² up to 25% is achievable. For further k ² enhancement, a hybrid reflector configuration is also examined, wherein HfN is applied only to the top high Z _a layer and W is applied to the others. The result indicates that C _p caused by the W layers is still significant, and k ² becomes worse in total.