Abstract: To provide a surface plasmon sensor for measuring a refractive index by which a refractive index can be easily measured with high accuracy without relying on an absorption curve. The surface plasmon sensor includes: a reflection plate which includes a metal layer having a periodic structure and on which a specimen is arranged; a light source which irradiates an incident light to the reflection plate; a light receiving part which receives a reflected light reflected on the reflection plate; and a measurement part which measures a refractive index of the specimen based on phase information on two kinds of waves which are included in reflected light reflected on a periodic structure surface and differ in polarization direction.

Abstract: To provide a surface plasmon sensor for measuring a refractive index by which a refractive index can be easily measured with high accuracy without relying on an absorption curve. The surface plasmon sensor includes: a reflection plate which includes a metal layer having a periodic structure and on which a specimen is arranged; a light source which irradiates an incident light to the reflection plate; a light receiving part which receives a reflected light reflected on the reflection plate; and a measurement part which measures a refractive index of the specimen based on phase information on two kinds of waves which are included in reflected light reflected on a periodic structure surface and differ in polarization direction.

Abstract: In order to provide a transducer suitable for an anisotropic substrate having the NSPUDT property, on the anisotropic piezoelectric substrate being cut to have the NSPUDT property, there is formed a transducer structure having an exciting electrode structure (21) and a reflector structure (22). When &lgr; is a wavelength of a fundamental surface acoustic wave, said exciting electrode structure (21) includes a positive electrode (23) having a plurality of electrode fingers arranged at a pitch &lgr; and a negative electrode (24) having at least one electrode finger interdigitally arranged between said electrode fingers of the positive electrode with a center distance of &lgr;/2. The reflector transducer (22) includes a plurality of electrode fingers arranged with a center distance of &lgr;/2, and a distance Lg between said exciting electrode structure (21) and the reflector structure (22) is set to Lg=(2n+1)&lgr;/4 (n being a positive integer).

Abstract: The surface acoustic wave functional element comprises a semiconductor layer provided on a piezoelectric substrate or a piezoelectric film substrate and makes use of interaction between a surface acoustic wave propagating on the substrate and electrons in the substrate layer, but has the semiconductor layer disposed outside above the propagation path for propagating a surface acoustic wave, comprises a plurality of grating electrodes perpendicularly above and to the propagation path and moreover the semiconductor layer comprises an active layer and a buffer layer lattice-matching thereto. By use of this surface acoustic wave functional element, a surface acoustic wave amplifier capable of providing a high amplification gain at a practical low voltage, a surface acoustic wave convolver having a higher efficiency than ever or the like are offered.

Abstract: A surface acoustic wave device including a piezoelectric substrate having NSPUDT behavior and a directionality reversed electrode structure including positive electrode, negative electrode and floating electrode. Positive and negative electrode fingers each having a width of .lambda./8 are arranged interdigitally at a pitch of .lambda. and floating electrode fingers having a width of 3 .lambda./8 are arranged between successive positive and negative fingers with an edge distance of .lambda./8. A directivity due to NSPUDT behavior of the substrate can be reversed. Positive and negative electrode fingers are arranged interdigitally at a pitch of .lambda. and between successive positive and negative electrode fingers are arranged floating electrode fingers having a reflecting coefficient different from that of the positive and negative electrodes.

Abstract: A surface acoustic wave device including a substrate made of a lithium tetraborate single crystal (Li.sub.2 B.sub.4 O.sub.7) whose cut and propagating direction are determined such that Euler cut angles (.psi., .theta., .phi.) are .psi.=+5.degree..about.-5.degree., .theta.=9.degree..about.29.degree. and 32.degree..about.86.degree. and .phi.=85.degree..about.95.degree., and an electrode structure formed on a surface of the substrate to realize a natural single-phase unidirectional transducer property together with an anisotropy of said substrate. A lithium tetraborate substrate having cut angles of (0.degree., 51.degree., 90.degree.) shows an ideal NSPUDT and a lithium tetraborate substrate having cut angles of (0.degree., 78.degree., 90.degree.) reveals a zero temperature coefficient of delay. A directionality reversed electrode structure or a directionality corrected electrode structure may be advantageously used.