Optical piezoelectric transducer for nano-ultrasonics

Kung Hsuan Lin, Gia Wei Chern, Cheng Ta Yu, Tzu Ming Liu, Chang Chi Pan, Guan Ting Chen, Jen Inn Chyi, Sheng Wen Huang, Pai Chi Li, Chi Kuang Sun

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Piezoelectric semiconductor strained layers can be treated as piezoelectric transducers to generate nanometer-wavelength and THz-frequency acoustic waves. The mechanism of nano-acoustic wave (NAW) generation in strained piezoelectric layers, induced by femtosecond optical pulses, can be modeled by a macroscopic elastic continuum theory. The optical absorption change of the strained layers modulated by NAW through quantum-confined Franz-Keldysh (QCFK) effects allows optical detection of the propagating NAW. Based on these piezoelectric-based optical principles, we have designed an optical piezoelectric transducer (OPT) to generate NAW. The optically generated NAW is then applied to one-dimensional (1-D) ultrasonic scan for thickness measurement, which is the first step toward multidimensional nano-ultrasonic imaging. By launching a NAW pulse and resolving the returned acoustic echo signal with femtosecond optical pulses, the thickness of the studied layer can be measured with <1 nm resolution. This nano-structured OPT technique will provide the key toward the realization of nano-ultrasonics, which is analogous to the typical ultrasonic techniques but in a nanometer scale.

Original languageEnglish
Pages (from-to)1404-1414
Number of pages11
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume52
Issue number8
DOIs
StatePublished - Aug 2005

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