1,721,014 research outputs found
Characterisation of photoalignment materials for photonic applications at visible and infrared wavelengths
No full textIn this paper we discuss the processing and characterisation of Linearly Polymerisable Polymers to align Liquid Crystal Prepolymers for use in photonic application. Preliminary results on uniform retardation waveplates for use in free space optics are given
A method for butt-coupling optical fibres to liquid crystal planar waveguides
No full textIn most optical applications of liquid crystals, namely liquid crystal displays and free-space optics, light propagates mainly perpendicular
to the substrates; in these cases the sealing of the device is not critical for the optical performance. As liquid crystals are gaining
interest in integrated optics applications (where the propagation is in the plane of the wafer), we also have to deal with at least two additional
facets for the light input and output. In this communication, we expose a simple and practical method to achieve effective interface
that shows good compatibility with nematic liquid crystal
Integrated optics devices based on liquid crystals
No full textWe describe the technology behind a platform for integrated optics based on liquid crystals. Design and technological issues are addressed and effective technological solutions are presented. The physical implementation of optical waveguides characterized by a practical and reproducible process based on preferential etching of crystalline silicon substrates are presented. Devices are manufactured by wet etching a Si substrates first and then by thermally growing thick SiO2 cladding layer.
A nematic liquid crystal is used as core of the waveguiding devices. Experimental results on polarizing properties and single mode propagation of infrared light are presented and discussed
Polarization independent optofluidic nematic liquid crystal channels
No full textWe present the fabrication and the characterization of waveguides made of a nematic liquid crystal infiltrated in PDMS channels. The molecular orientation inside the waveguides allows only 0.3 dB variation of light transmission versus polarization
Observation of tunable optical filtering in photosensitive composite structures containing liquid crystals
No full textWe 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 optical signal to be filtered. Exposure to a low power visible light beam modifies the azodye
molecular configuration, thus allowing the filtered wavelength to be tuned over a 6.6 nm range. Simulations
of the filtering response are well described with our experimental findings
All optical tunable nematic liquid crystal waveguide
No full textAll-optical control of a rectangular waveguide with
liquid crystal is theoretically investigated. Light propagation is established with low input power control, that excites optical nonlinearity due to optically induced reorientational effect
Geometrical and fluidic tuning of periodically modulated thin metal films
No full textWe numerically demonstrate near-zero transmission of light through two-dimensional arrays of isolated gold rings. The analysis of the device as an optofluidic sensor is presented to demonstrate the tuning of the device in relation to variations of volume and refractive index of an isotropic fluid positioned over the structure. We also evaluate the performance of the device with respect to geometrical parameters of the rings
All-optical intensity modulation of near infrared light in a liquid crystal channel waveguide
No full textWe demonstrate a nonlinear optical channel waveguide made of E7 nematic liquid crystal infiltrated in a silica on silicon groove. Near infrared light at the wavelength of 1560 nm fiber coupled to the core of the liquid crystal waveguide was optically modulated by an optical beam with power below
25 mW by exploiting the optical Freedericks transition. By modeling the optical molecular reorientation in the nematic liquid crystal confined in a waveguiding geometry we are able to reproduce the experimental results
Tunable integrated optical filter made of a glass ion-exchanged waveguide and an electro-optic composite holographic grating
Full text linkWe report the fabrication and the optical characterization of a hybrid tunable integrated optical filter. It consists of a diffused ionexchanged 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), is made of alternating stripes of polymer and liquid crystal acting as overlayer for the underneath waveguide. The filter structure includes aluminum coplanar electrodes to electrically control the grating properties, allowing the tunability of the filter. The electric driving power required to tune the filter obtained was in the range of submilliwatts due to the efficient liquid crystal electro-optic effect
Plasmon resonance optical tuning based on photosensitive composite structures
Full text linkThis paper reports a numerical investigation of a periodic metallic structure sandwiched between two quartz plates. The volume comprised between the quartz plates and the metallic structure is infiltrated by a mixture of azo-dye-doped liquid crystal. The exposure to a low power visible light beam modifies the azo dye molecular configuration, thus allowing the wavelength shift of the resonance of the system. The wavelength shift depends on the geometry of the periodic structure and it also depends on the intensity of the visible light beam
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