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Demetri Psaltis

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Publications associées (271)

Light modulation enabled by liquid crystal microflows

Julien Cuennet, Demetri Psaltis, Andreas Vasdekis, Luciano De Sio

In a previous paper, 1 we proposed an optofluidic modulator based on peristaltic flow. A microchannel made of polydimethylsiloxane is filled with nematic liquid crystal molecules that align homeotropically in the steady state. Once we apply a periodic peri ...

2011

Optofluidic membrane interferometer: An imaging method for measuring microfluidic pressure and flow rate simultaneously on a chip

Demetri Psaltis, Wuzhou Song

We present a novel image-based method to measure the on-chip microfluidic pressure and flow rate simultaneously by using the integrated optofluidic membrane interferometers (OMIs). The device was constructed with two layers of structured polydimethylsiloxa ...

American Institute of Physics2011

Optofluidic modulator based on peristaltic nematogen microflows

Julien Cuennet, Demetri Psaltis, Andreas Vasdekis, Luciano De Sio

Nematogens rotate by the application of external fields, thereby enabling optical modulation. This principle has had a profound impact on our daily lives through the plethora of liquid-crystal displays in use around us(1,2). However, the wider use of nemat ...

Nature Publishing Group2011

Digital reverse propagation in focusing Kerr media

Alexandre Goy, Demetri Psaltis

Lenses allow the formation of clear images in homogeneous linear media. Holography is an alternative imaging method, but its use is limited to cases in which it provides an advantage, such as three-dimensional imaging. In nonlinear media, lenses no longer ...

2011

Superoscillatory diffraction-free beams

Demetri Psaltis

It is theoretically shown that by superimposing diffraction-free solutions of the Helmholtz equation, one can construct localized diffraction-free beams that pass through predetermined points on subwavelength distances. These beams are based on the phenome ...

Optical Society of America2011

Silicon oxide deposition for enhanced optical switching in polydimethylsiloxane-liquid crystal hybrids

Julien Cuennet, Demetri Psaltis, Andreas Vasdekis, Luciano De Sio

We report an optical switch based on a diffraction grating by combining PDMS microstructures with a photo-responsive Nematic Liquid Crystal (NLC). The grating was realized via replica molding and was subsequently coated with a thin SiO layer. SiO induced a ...

2011

Imaging with second-harmonic radiation probes in living tissue

Rachel Grange, Demetri Psaltis, Thomas Jean Victor Marie Lanvin, Chia-Lung Hsieh, Ye Pu, Ye Pu

We demonstrate that second-harmonic radiation imaging probes are efficient biomarkers for imaging in living tissue. We show that 100 nm and 300 nm BaTiO3 nanoparticles used as contrast markers could be detected through 50 mu m and 120 mu m of mouse tail ti ...

2011

Huygens-Fresnel diffraction and evanescent waves

Demetri Psaltis

Based on a modified Huygens-Fresnel principle valid in the near field, we analytically verify the exponential wave decay of evanescent waves. This field decay along the propagation direction can be considered as the result of interference between elementar ...

2011

Pneumatically tunable optofluidic 2 x 2 switch for reconfigurable optical circuit

Demetri Psaltis, Wuzhou Song

We presented a pneumatically tunable 2 x 2 optofluidic switch for on-chip light routing that was controlled by compressed air. The device was fabricated with an optically clear elastomer-polydimethylsiloxane ( PDMS)-by soft-lithography. The optical switchi ...

Royal Society of Chemistry2011

Imaging through turbid layers by scanning the phase conjugated second harmonic radiation from a nanoparticle

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Grégoire Pierre Jean Laporte, Ye Pu

We demonstrate imaging through a turbid layer by using digital phase conjugation of the second harmonic field radiated from a beacon nanoparticle. We show that the phase-conjugated focus can be displaced from its initial position by illuminating the same r ...

2010

Second harmonic generation from nanocrystals under linearly and circularly polarized excitations

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Ye Pu

We study second harmonic generation (SHG) from noncentrosymmetric nanocrystals under linearly polarized (LP) and circularly polarized (CP) excitations. Theoretical models are developed for SHG from nanocrystals under both plane-wave and focused excitations ...

2010

Optofluidic distributed feedback dye laser via evanescent gain

Demetri Psaltis, Andreas Vasdekis, Wuzhou Song

We demonstrate optofluidic evanescent dye lasers based on two types of solid distributed feedback (DFB) grating cavities- the first order linear DFB gratings which gives in-plane laser emitting and second order circular DFB gratings which gives surface las ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2010

Pneumatically tunable optofluidic dye laser

Demetri Psaltis, Wuzhou Song

We presented a tunable optofluidic dye laser with integrated elastomeric air-gap etalon controlled by air pressure. The chip was fabricated with polydimethylsiloxane (PDMS) via replica molding. It comprises a liquid waveguide and microscale air-gap mirrors ...

2010

Optofluidic pressure sensor based on interferometric imaging

Demetri Psaltis, Wuzhou Song

We present a chip-scale optofluidic interferometric sensor for measuring liquid pressure based on an imaging method. The chip was constructed with a polymer by multilayer soft lithography. It consists of a flexible air gap optical cavity, which, upon illum ...

2010

Microfluidic assays for DNA manipulation based on a block copolymer immobilization strategy

Demetri Psaltis, Andreas Vasdekis

Methods to manipulate and visualize isolated DNA and oligonucleotide strands are important for investigation of their biophysics as well as their interactions with proteins. Herein, we report such a method by combining a block copolymer surface functionali ...

American Chemical Society2010

Characterization of the cytotoxicity and imaging properties of secondharmonic nanoparticles

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Ye Pu

We develop second-harmonic nanoparticles as the contrast agents for cell imaging. Second-harmonic nanoparticles show promise as cell imaging probes due to their non-bleaching, non-blinking, and coherent signal. Nanoparticles of noncentrosymmetric crystal s ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2010

Nonlinear optical properties of core-shell nanocavities for enhanced second-harmonic generation

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Ye Pu

A nonlinear optical plasmonic core-shell nanocavity is demonstrated as an efficient, subwavelength coherent light source through second-harmonic generation. The nonlinear optical plasmonic nanocavity incorporates a noncentrosymmetric medium, which utilizes ...

2010

Tunable optofluidic dye laser with novel cavity

Demetri Psaltis, Andreas Vasdekis, Wuzhou Song

We present a pressured mediated tunable optofluidic dye laser with novel cavity. The dye laser chip was fabricated with Polydimethylsiloxane (PDMS) via replica molding and has none nano-features. It comprises a liquid waveguide and micro-scale air-gap cham ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2010

Three-dimensional harmonic holographic microcopy using nanoparticles as probes for cell imaging: erratum

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Ye Pu

An error was made in calculating the polarization dependent second harmonic response of barium titanate nanoparticles. We have corrected the error and repeated the comparison with the experimental results. (C) 2010 Optical Society of America ...

2010

Bioconjugation of barium titanate nanocrystals with immunoglobulin G antibody for second harmonic radiation imaging probes

Rachel Grange, Demetri Psaltis, Chia-Lung Hsieh, Ye Pu, Ye Pu

The second harmonic generation (SHG) active nanocrystals have been demonstrated as attractive imaging probes in nonlinear microscopy due to their coherent, non-bleaching and non-blinking signals with a broad flexibility in the choice of excitation waveleng ...

Elsevier2010

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