60 MHz multidomain ultrasonic transducer

Multidomain periodically poled structure of 80 inversely poled domains of 50-micron-width each was fabricated in a 350-micron-thick 42-degrees-Y-rotated cut of LiTaO3 wafer. A multidomain structure in a ferroelectric plate is characterized by its own domain resonance where acoustic wavelength is equal to the domain period, and ultrasound speed is ∼6 km/s for LiTaO3 [I. V. Ostrovskii and A. B. Nadtochiy, Appl. Phys. Lett. 86, 222902 (2005)]. The rf impedance of the transducer as a function of frequency demonstrates a sharp resonance-antiresonance behavior at 57.6–60 MHz band (sample LTYR42B5a). The resonance observed is a pure multidomain resonance because crystal length is much longer than domain width. Overall dimensions of this transducer are 4×4×0.35 mm3, and irradiating surface area is 4×0.35 mm2. Two such transducers were used to model a delay line with water as a medium of propagation. A 1-μs burst with 59 MHz central frequency was delayed for 4.3 μs in the water. In conclusion, we present a new high frequency transducer for various applications in non-destructive testing, medicine, and biology [Patent Pending]. Experimental measurements and theoretical calculations are in good agreement.