Design and Fabrication of Fresnel Lens and ZnO Thin-Film Transducer

Pan, Min; Bui, Tuan-Anh; Nien, Yu Chuan; Shih, Wen Ching

doi:10.1143/jjap.50.07hd02

Cited by 7 publications

(2 citation statements)

References 23 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the c-axis tilted ZnO layer is grown instead of the c-axis normal layer, because the sputtered particles tilt to the substrate plane. 24,25) The ZnO transducer with the c-axis tilted ZnO/c-axis normal ZnO multilayer thus can be fabricated continuously without changing the conditions during the deposition.…”

Section: Transducer Characterizationmentioning

confidence: 99%

Wideband Multimode Transducer Consisting of c-Axis Tilted ZnO/c-Axis Normal ZnO Multilayer

Takayanagi

Yanagitani

Matsukawa

2012

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

Wideband ultrasonic transducers are required for acoustic imaging and nondestructive evaluation. In this study, we have fabricated transducer consisting of c-axis tilted ZnO/c-axis normal ZnO multilayer on the Au(111)/Ti/silica glass substrate. We have investigated the crystalline orientations and frequency characteristics of the multilayer transducer. An X-ray diffraction analysis and a scanning electron microscopy analysis of the transducer revealed that the c-axis normal ZnO layer was grown on the Au(111) layer during the initial stage of ZnO layer deposition. As ZnO grain growth proceeded, c-axis normal growth change to the c-axis tilted ZnO layer growth. This multilayer transducer excited secondovertone modes of longitudinal and shear waves as well as the fundamental mode in the UHF range. Therefore, the frequency bandwidth of the multilayer transducer was broader than that of a single layer transducer consisting of a c-axis tilted ZnO layer.

show abstract

Section: Transducer Characterizationmentioning

confidence: 99%

Wideband Multimode Transducer Consisting of c-Axis Tilted ZnO/c-Axis Normal ZnO Multilayer

Takayanagi

Yanagitani

Matsukawa

2012

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…Annular array transducers have already been developed for nondestructive testing, medical uses, and industrial applications. [1][2][3][4][5][6][7][8] Various lens types, such as the curved type, [2][3][4][5][6] flat type, 7) and step height type, 8) have been developed to obtain effective focusing. They consist of a number of equal-area elements and allow the focal point to be shifted by electrical control.…”

Section: Introductionmentioning

confidence: 99%

Development of a Long-Focal-Range Annular Array Ultrasonic Transducer

Korai¹,

Baba²

2012

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

Conventional annular array transducers designed with Fresnel divided elements have a limited maximum size of the aperture of the transducer. In this study, we designed and fabricated a prototype of a large-aperture annular array transducer to inspect next-generation semiconductors. A new annular array pattern was designed with a wide focal range and a large focal length using equal areas for the inner elements and equal stroke widths for the outer elements. The prototype was fabricated by epoxy bonding with a patterned metal electrode on a flexible printed circuit and a piezoelectric copolymer. As a result of evaluation, we obtained a fine spatial resolution below 100 µm and a narrow relative sensitivity variation of 6.5 dB for a large focal length and a wide focal range from 10 to 30 mm.

show abstract

Nanometer-thick flat lens with adjustable focus

Son

Vallée

et al. 2014

Applied Physics Letters

View full text Add to dashboard Cite

We report laser beam focusing by a flat, homogeneous film with a thickness of less than 100 nm. The effect relies on refractive index changes occurring in vanadium dioxide as it undergoes a phase transition from insulator to metal. Phase front curvature is achieved by means of temperature gradients, and adjustable focal lengths from infinity to 30 cm are attained. V C 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4903887] Thin flat lenses have found applications in areas such as integrated optics and satellite optical instruments, where lightweight and small-volume optical components are desired, as well as x-ray optics, where standard lens materials are ineffective. While the traditional approach to creating thin lenses is based on the Fresnel zone plate design, there has been a resurgence of activity exploiting effects of nanoplasmonics and metamaterials. For example, a quasiperiodic arrangement of sub-wavelength holes on a thin gold film was found to focus light to sub-wavelength spatial resolution. 1-3 Similarly, light focusing by ultrathin lenses was demonstrated by exploiting the properties of nano-antennas etched on a surface, 4,5 thus forming a type of optically functionalized metasurface. 6,7 In this paper, we report yet an alternative method for focusing light with a thin layer of material. There are three key differences that distinguish this work from previous studies:(1) it exploits a different mechanism, namely, the large refractive index change occurring during a phase transition from insulator-to-metal, (2) the focusing capability is dynamic, and can be adjusted in real time, and (3) the material used is uniform and does not require prior physical patterning. In the latter aspect, it is analogous to gradient-index (GRIN) and other such thin lenses, [8][9][10][11][12] with the exception that its index of refraction is not spatially profiled beforehand.When light interacts with a layer of vanadium dioxide (VO 2 ), it acquires a phase shift which depends on the state of the material. In the temperature range where VO 2 undergoes a transition from insulator to metal (roughly 50-80 C), the optical phase shift is approximately linear with temperature, as was shown in a previous study. 13 Figure 1 illustrates the concept. Figure 2 presents ellipsometry measurements showing the change in refractive index as VO 2 undergoes a phase transition. Given the complex refractive indices, Fresnel reflection coefficients at the air/VO 2 and VO 2 /substrate interfaces introduce phase shifts of 0.51 rad and 0.75 rad, respectively, during the phase transition of the material. Meanwhile, the round-trip propagation phase in the layer varies by À1.0 rad. From this we conclude that both propagation and reflection phases are responsible for the observed phase shift.From Figure 1(b), we see that between a temperature T A (the onset of the phase transition) and a temperature T B (the end of the phase transition), the optical phase shift from VO 2 changes by some amount D/. As a result, by mean of a temperature gradien...

show abstract

Design and Fabrication of Fresnel Lens and ZnO Thin-Film Transducer

Cited by 7 publications

References 23 publications

Wideband Multimode Transducer Consisting of c-Axis Tilted ZnO/c-Axis Normal ZnO Multilayer

Wideband Multimode Transducer Consisting of c-Axis Tilted ZnO/c-Axis Normal ZnO Multilayer

Development of a Long-Focal-Range Annular Array Ultrasonic Transducer

Nanometer-thick flat lens with adjustable focus

Contact Info

Product

Resources

About