All-fibre acousto-optic modulator using ZnO piezoelectric actuators

Wuethrich, Christian; Müller, C.; Fox, Glen R.; Limberger, H.G.

doi:10.1016/s0924-4247(97)01755-x

Cited by 26 publications

(8 citation statements)

References 6 publications

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“…More recently, the growing interest in applications of zinc oxide films in varistors, in piezoelectric devices and in acousticoptical systems has stimulated studies that correlate the film morphology with its electrical properties [2][3][4][5]. It is well known that electrical properties of doped-ZnO varistors depend on grain boundary effects, which are, in principle, characteristics of ZnO bulk structure; the granular morphology is responsible for its low conductivity at low fields, but above a critical field, tunneling effect across the potential barriers at the grain boundaries enhances considerably the material conductivity [6].…”

Section: Introductionmentioning

confidence: 99%

UV and ozone influence on the conductivity of ZnO thin films

Gonçalves¹,

Pimentel²,

Fortunato³

et al. 2006

Journal of Non-Crystalline Solids

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Complex impedance measurements were used to analyze the influence of ultraviolet and ozone gas on the electronic behaviour of ZnO films grown by rf magnetron sputtering. The data show that UV exposure strongly increases the ac conductivity of the film at very low frequencies, and that after ozone exposure it recovers the original value. At high frequencies, however, UV-light exposure it does not change the conductivity but the ozone acts in the sense to decrease it. Two distinct mechanisms, related to two relaxation time distributions are clearly observed: they are superimposed in the virgin sample, but they split forming two semicircles in the z 00 (f) À z 0 (f) diagrams when the samples are treated with UV and/or ozone gas. A combination of the bruggeman effective medium approximation (BEMA) with the random free energy barrier model is used to fit the data and to explain the ac conductivity variation phenomena observed.

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Section: Introductionmentioning

confidence: 99%

UV and ozone influence on the conductivity of ZnO thin films

Gonçalves¹,

Pimentel²,

Fortunato³

et al. 2006

Journal of Non-Crystalline Solids

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“…54 Further SNR improvement can be achieved by tuning the mechanical resonances in the piezoelectric coated optical fiber to Larmor frequency. 55 The resonance frequency is tunable with metal layer and piezo layer thicknesses, which are very controllable such that one can match the desired Larmor frequency based on the targeted field strength of the MR scanner (0.55T, 1.5T, and 3T) for optimum coupling. Given this SNR improvement, the antenna size can be further decreased which will allow integration with low profile interventional devices such as smaller catheters, guidewires and biopsy needles.…”

Section: Discussionmentioning

confidence: 99%

Real‐time device tracking under MRI using an acousto‐optic active marker

Yaras

Yildirim

Herzka

et al. 2020

Magnetic Resonance in Med

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This work aims to demonstrate the use of an "active" acousto-optic marker with enhanced visibility and reduced radiofrequency (RF)-induced heating for interventional MRI. Methods: The acousto-optic marker was fabricated using bulk piezoelectric crystal and π-phase shifted fiber Bragg grating (FBGs) and coupled to a distal receiver coil on an 8F catheter. The received MR signal is transmitted over an optical fiber to mitigate RF-induced heating. A photodetector converts the optical signal into electrical signal, which is used as the input signal to the MRI receiver plug. Acousto-optic markers were characterized in phantom studies. RF-induced heating risk was evaluated according to ASTM 2182 standard. In vivo real-time tracking capability was tested in an animal model under a 0.55T scanner. Results: Signal-to-noise ratio (SNR) levels suitable for real-time tracking were obtained by using high sensitivity FBG and piezoelectric transducer with resonance matched to Larmor frequency. Single and multiple marker coils integrated to 8F catheters were readout for position and orientation tracking by a single acousto-optic sensor. RF-induced heating was significantly reduced compared to a coax cable connected reference marker. Real-time distal tip tracking of an active device was demonstrated in an animal model with a standard real-time cardiac MR sequence. Conclusion: Acousto-optic markers provide sufficient SNR with a simple structure for real-time device tracking. RF-induced heating is significantly reduced compared to conventional active markers. Also, multiple RF receiver coils connected on an acousto-optic modulator can be used on a single catheter for determining catheter orientation and shape.

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“…Functioning as electromechanical actuator, piezoelectric thin film coatings on optical fibers have been used in several types of telecommunication device (Trolier-McKinstry et al, 1999). Several designs for optical phase modulators (Jarzynski, 1984) and tunable Bragg gratings (Wuethrich et al, 1998) have been reported. The most widely used commercial piezoelectric material is the various phases of lead zirconate titanate (PZT).…”

Section: Introductionmentioning

confidence: 99%

Static Electromechanical Response of Piezoelectric Tubes as Sensors and Actuators

Shiah

Huang

2006

Journal of Intelligent Material Systems and Structures

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This article deals with the fully coupled electromechanical response of an infinitely long piezoelectric tube as a sensor or an actuator. By adopting the variational approach for generalized loading conditions and utilizing Hamilton’s principle, we derive the governing differential equations of an infinitely long piezoelectric tube subjected to natural boundary conditions. For studying the direct and converse effects of the piezoelectric tube, the governing equations obtained are solved to give the exact solutions corresponding to different boundary conditions prescribed for the tube functioning as a sensor or an actuator. For numerical illustrations of our analysis, an application is investigated where optical fibers are coated with polyvinylidene difluoride or lead zirconate titanate. The same problems are also solved by ANSYS for numerical comparisons. With a discrepancy of 3–5% at most, good agreements between both results are observed.

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All-fibre acousto-optic modulator using ZnO piezoelectric actuators

Cited by 26 publications

References 6 publications

UV and ozone influence on the conductivity of ZnO thin films

UV and ozone influence on the conductivity of ZnO thin films

Real‐time device tracking under MRI using an acousto‐optic active marker

Static Electromechanical Response of Piezoelectric Tubes as Sensors and Actuators

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