Observation of the Roundtrips of Surface Acoustic Waves on a Single Crystal LiNbO₃ Ball

Abstract

Propagation of surface acoustic waves (SAWs) was investigated on a single lithium niobate (LiNbO 3 ) ball of 1 inch diameter. We found ten specific routes, on which the roundtrips of SAWs are observed, and one or more specific routes, on which the multiple reflections of bulk waves are observed. Since the temperature coefficient is similar on each route of the SAW, one route can be used to correct the temperature dependency of all other routes, and the other routes can be used as multiple-gas sensors by coating various reactive thin films along each route.

Principle and application of ball surface acoustic wave (SAW) sensor

“…In these circumstances, we have studied property of SAW on a ball and developed ball SAW devices [8][9][10][11][12][13][14] based on the multiple roundtrip propagation of SAW along a narrow path on the surface of ball without the diffraction effect [8]. Subsequent theoretical work predicted a natu-rally collimated beam of SAW [9], which was experimentally verified by using a piezoelectric transducer [10] and a laser probe [11].…”

“…Subsequent theoretical work predicted a natu-rally collimated beam of SAW [9], which was experimentally verified by using a piezoelectric transducer [10] and a laser probe [11]. Present ball SAW device is composed of a piezoelectric crystal ball with an IDT of a proper width, directly fabricated along a proper route [12][13][14]. By using a proper length of IDT, collimated SAW beams travel many times along the spherical surface [9][10][11][12][13][14], and the roundtrip time can be precisely measured [8].…”

Principle and application of ball SAW devices

“…For [9,19,20], and a method to form a piezoelectric thin film on a non-piezoelectric material ball [8]. Multiple roundtrip characteristics on the crystal ball have been discovered experimentally.…”

“…For the development of SAW devices using a natural collimate beam on a ball, there is a method to send and receive a SAW by forming an electrode on a piezoelectric single crystal ball [9,19,20], and a method to form a piezoelectric thin film on a non-piezoelectric material ball [8]. Multiple roundtrip characteristics on the crystal ball have been discovered experimentally.…”

“…For instance, on a LiNbO 3 ball, there are several roundtrip routes, as can be seen in Fig. 4 [19,20]. Here, the numbers in parentheses represent the Euler angle designating the roundtrip route.…”