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| 2. |
- Grilli, Simonetta, et al.
(author)
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A Mach-Zehnder interferometric system for measuring the refractive indices of uniaxial crystals
- 2002
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In: Optics communications. - 0030-4018. ; 202, s. 9-15
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Journal article (peer-reviewed)abstract
- We report a new interferometric technique for measuring the ordinary and extraordinary refractive indices of uniaxial crystals. The technique is based on the measurement of the rotation-dependent phase changes of the optical path length in crystal plates. Accurate measurement of the phase shift as a function of the rotation of the sample is achieved by using a fast-Fourier-transform based fringe analysis method for phase retrieval. The principle of the method is discussed and measurements of the ordinary and extraordinary refractive indices of a lithium niobate crystal are reported.
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| 3. |
- Grilli, Simonettta, et al.
(author)
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In-situ visualization, monitoring and analysis of electric field domain reversal process in ferroelectric crystals by digital holography
- 2004
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In: Optics express. - 1094-4087. ; 12:9, s. 1832-1842
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Journal article (peer-reviewed)abstract
- In-situ monitoring of domain reversal in congruent lithium niobate by a digital holographic technique is described. While the ferroelectric polarization is reversed by electric field poling, the two-dimensional distribution of the phase shift, due mainly to the linear electro-optic and piezoelectric effects, is measured and visualized. Digital holography is used to reconstruct both amplitude and phase of the wavefield transmitted by the sample to reveal the phase shift induced by adjacent reversed domains during the poling. The resulting movies of both amplitude and phase maps, for in-situ visualization of domain pattern formation, are shown. The possibility of using the technique as tool for monitoring in real-time the periodic poling of patterned samples is discussed.
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| 4. |
- Grilli, Simonetta, et al.
(author)
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Investigation on reversed domain structures in lithium niobate crystals patterned by interference lithography
- 2003
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In: Optics express. - 1094-4087. ; 11, s. 392-
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Journal article (peer-reviewed)abstract
- We demonstrate fabrication of periodically poled lithium niobate samples by electric field poling, after patterning by interference lithography. Furthermore we investigate the poling process at an overpoling regime which caused the appearance of submicron dot domains very similar to those induced by backswitch but different in nature. We show the possibility for realizing submicron-scaled three-dimensional domain patterns that could be applied to the construction of photonic crystals and in nonlinear optics. We show that high etch-rate applied to such structures allows to obtain pyramidal-like submicron relief structures which in principle could find application for waveguide construction in photonic bandgap devices
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| 5. |
- Grilli, Simonetta, et al.
(author)
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Visualization of optical deflection and switching operations by a domain-engineered-based LiNbO electro-optic device
- 2003
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In: Optics express. - 1094-4087. ; 11, s. 1212-
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Journal article (peer-reviewed)abstract
- An electro-optic device applied as an optical beam deflector and switch at different wavelengths has been built and tested. The electro-optic device is based on domain-engineered lithium niobate (LiNbO3). In this paper, for the first time, its operation has been visualized by an imaging camera. The device has been characterized both at the visible wavelength (632.8 nm) and at a typical telecom wavelength (1532 nm). Furthermore, the device has been tested as an amplitude modulator in the mid-infrared region as well, at a wavelength of similar to4.3 mum, where no Pockels cells are available. A detailed description of this device is given, and the experimental results are discussed.
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| 6. |
- Paturzo, M., et al.
(author)
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Investigation of electric internal field in congruent LiNbO3 by electro-optic effect
- 2004
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In: Applied physics letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85, s. 5652-5654
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Journal article (peer-reviewed)abstract
- We investigate the effect of the defect-induced internal field on the electro-optic behavior of z-cut congruent lithium niobate crystals. We measure, by a spatially resolved interferometric technique, the phase retardation due to an external applied voltage occurring in two regions with opposite ferroelectric polarization. When measurements are performed just after electrical poling, the two opposite domains show a different electro-optic behavior. We interpret this as due to an elastic component of the internal field. In fact, the asymmetric behavior disappears when the sample is thermally annealed, i.e., when the internal field vanishes
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| 7. |
- Andersson, Mike, et al.
(author)
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Development of a ChemFET sensor with molecular films of porphyrins as sensitive layer
- 2001
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In: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 567-571
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Journal article (peer-reviewed)abstract
- The interaction of chemical species with molecular films of porphyrins causes variations of the work function of the film itself, as it has been recently demonstrated by using the Kelvin probe technique. This characteristic makes porphyrins films suitable to be used as sensitive layers in ChemFET sensors. In this paper, we present a preliminary report about the fabrication and testing of such gas sensitive devices. The technological solutions towards an optimised device are also illustrated and discussed. © 2001 Elsevier Science B.V.
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