Photorefractive direct laser writing

Vittadello, Laura; Zaltron, Annamaria; Argiolas, N.; Bazzan, M.; Rossetto, Nicola; Signorini, Raffaella

doi:10.1088/0022-3727/49/12/125103

Cited by 18 publications

(16 citation statements)

References 25 publications

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“…The maxima (minima of D(ηα, η β , ν)) are obtained at ∆η a,b = 0 and ∆ν a,b = 0, indicating that the two spectra with the higest degree of similarity corresponds to lattices (DLW) technique [25,26]. We used three gratings made up of N = 300 lines all written in the same substrate: (a) a periodic grating with spacing L = 23µm; two Fibonacci gratings with (b) L = 23µm and S = 17µm (η a 1 = 17/6) and (c) L = 23µm and S = 15µm (η b 3 = 15/8) respectively.…”

Section: Similarity Of Diffraction Patternsmentioning

confidence: 99%

“…To test experimentally the diffraction from FL's, a series of quasi-periodic diffraction gratings have been prepared using a photorefractive direct laser writing (DLW) technique [25]. This technique consists in scanning with a focused laser beam a photorefractive sample, engraving on it a series of lines with a modified refractive index with respect to the rest of the sample.…”

Section: Appendix D: Experimental Setupmentioning

confidence: 99%

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Equivalence classes of Fibonacci lattices and their similarity properties

et al. 2016

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We investigate, theoretically and experimentally, the properties of Fibonacci lattices with arbitrary spacings. Different from periodic structures, the reciprocal lattice and the dynamical properties of Fibonacci lattices depend strongly on the lengths of their lattice parameters, even if the sequence of long and short segment, the Fibonacci string, is the same. In this work we show that by exploiting a self-similarity property of Fibonacci strings under a suitable composition rule, it is possible to define equivalence classes of Fibonacci lattices. We show that the diffraction patterns generated by Fibonacci lattices belonging to the same equivalence class can be rescaled to a common pattern of strong diffraction peaks thus giving to this classification a precise meaning. Furthermore we show that, through the gap labeling theorem, gaps in the energy spectra of Fibonacci crystals belonging to the same class can be labeled by the same momenta (up to a proper rescaling) and that the larger gaps correspond to the strong peaks of the diffraction spectra. This observation makes the definition of equivalence classes meaningful also for the spectral and therefore dynamical and thermodynamical properties of quasicrystals. Our results apply to the more general class of quasiperiodic lattices for which similarity under a suitable deflation rule is in order

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Section: Similarity Of Diffraction Patternsmentioning

confidence: 99%

Section: Appendix D: Experimental Setupmentioning

confidence: 99%

Equivalence classes of Fibonacci lattices and their similarity properties

et al. 2016

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“…For this aim, an interesting alternative to polymeric substrate is lithium niobate (LN), which can be worked as a glass substrate and presents a unique combination of optical and electrical properties. As a matter of a fact, in the field of integrated optics, LN is a well-known material for its properties that have been exploited for the realization of a wide range of optical devices, such as optical modulators [ 18 ], waveguides [ 19 ], second harmonic generators [ 20 ], photorefractive laser writing [ 21 ], or self-written waveguides [ 22 ]. Furthermore, very recently LN has been also demonstrated as a valuable substrate with which to realize microfluidic circuits, such as droplet generators [ 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Opto-Microfluidic System for Absorbance Measurements in Lithium Niobate Device Applied to pH Measurements

Zamboni

Zaltron

Izzo

et al. 2020

Sensors

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The aim of Lab-on-a-chip systems is the downscaling of analytical protocols into microfluidic devices, including optical measurements. In this context, the growing interest of the scientific community in opto-microfluidic devices has fueled the development of new materials. Recently, lithium niobate has been presented as a promising material for this scope, thanks to its remarkable optical and physicochemical properties. Here, we present a novel microfluidic device realized starting from a lithium niobate crystal, combining engraved microfluidic channels with integrated and self-aligned optical waveguides. Notably, the proposed microfabrication strategy does not compromise the optical coupling between the waveguides and the microchannel, allowing one to measure the transmitted light through the liquid flowing in the channel. In addition, the device shows a high versatility in terms of the optical properties of the light source, such as wavelength and polarization. Finally, the developed opto-microfluidic system is successfully validated as a probe for real-time pH monitoring of the liquid flowing inside the microchannel, showing a high integrability and fast response.

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“…Inorganic photosensitive materials such as photorefractive crystals or photosensitive glass offer the ability to create non-volatile embedded refractive index structures through a postprocessing thermal treatment, while offering reasonable one-photon sensitivity for DLW and holographic patterning [11][12][13]. Alternatively, the refractive index of most transparent amorphous or crystalline inorganic material can be modified at the focus of a sufficiently high intensity femtosecond pulse train [14,15].…”

Section: Introductionmentioning

confidence: 99%

Transport-of-intensity-based phase imaging to quantify the refractive index response of 3D direct-write lithography

et al. 2018

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Precise direct-write lithography of 3D waveguides or diffractive structures within the volume of a photosensitive material is hindered by the lack of metrology that can yield predictive models for the micron-scale refractive index profile in response to a range of exposure conditions. We apply the transport of intensity equation in conjunction with confocal reflection microscopy to capture the complete spatial frequency spectrum of isolated 10 μm-scale gradient-refractive index structures written by single-photon direct-write laser lithography. The model material, a high-performance two-component photopolymer, is found to be linear, integrating, and described by a single master dose response function. The sharp saturation of this function is used to demonstrate nearly binary, flat-topped waveguide profiles in response to a Gaussian focus.

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Photorefractive direct laser writing

Cited by 18 publications

References 25 publications

Equivalence classes of Fibonacci lattices and their similarity properties

Equivalence classes of Fibonacci lattices and their similarity properties

Opto-Microfluidic System for Absorbance Measurements in Lithium Niobate Device Applied to pH Measurements

Transport-of-intensity-based phase imaging to quantify the refractive index response of 3D direct-write lithography

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