Rita Asquini

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We report the diffraction properties at wavelengths of 632.8 and 1550 nm for volume transmission gratings made of a sequence of continuously aligned nematic liquid-crystal layers separated by isotropic polymer slices. The gratings are generated by holographically curing a solution of liquid crystal diluted in an isotropic prepolymer by means of a laser beam(More)
In this paper we review the state of the art in the field of liquid-crystal tunable guided-wave photonic devices, a unique type of fill-once, molecular-level actuated, optofluidic systems. These have recently attracted significant research interest as potential candidates for low-cost, highly functional photonic elements. We cover a full range of(More)
We report on the investigation and characterization of an optically tunable filtering effect, observed in a waveguide grating made of alternated strips of photocurable polymer and a mixture of azo-dye-doped liquid crystal. The grating is sandwiched between two borosilicate glasses, one of which includes an ion-exchanged channel waveguide, which confines the(More)
We report the fabrication and the optical characterization of a hybrid tunable integrated optical filter. It consists of a diffused ion-exchanged channel waveguide on a borosilicate glass substrate with a cover of the same glass to form a gap filled with a holographic grating. The grating morphology, called POLICRYPS (POlymer LIquid CRYstal Polymer Slices),(More)
We propose and numerically investigate a versatile and easy-to-realize configuration for a guided-wave voltage-tunable distributed feedback grating based on reorientation in nematic liquid crystal and coplanar comb electrodes. The device has a wide tuning range exceeding 100 nm and covers C and L bands for wavelength division multiplexing.
We propose a versatile guided-wave geometry encompassing electro-optic control for signal routing. A zero-gap directional coupler in liquid crystal can switch between two output states in the guide plane, permitting signal rerouting with modulation voltages as small as 70 mV. In the absence of an applied bias, no guiding--hence no modal output--is provided(More)
Nematic liquid crystals (NLC) consist of dielectrically anisotropic molecules in a fluid state; under proper anchoring at the boundaries of a cell, these elongated molecules tend to align, exhibiting a degree of orientational order and behaving as an optically birefringent uniaxial. NLC are transparent from the ultraviolet to the mid-infrared and exhibit a(More)
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