Eli Simova

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Linearly polarized femtosecond light pulses, focused inside fused silica to an intensity that leads to multiphoton ionization, produce arrayed planes of modified material having their normal parallel to the laser polarization. The planes are < or = 10 nm thick and are spaced at approximately lambda/2 in the medium for free space wavelengths of both 800 and(More)
We fabricate microchannels in fused silica by femtosecond laser irradiation followed by etching in diluted hydrofluoric acid. We show a dramatic dependence of the etch rate on the laser polarization, spanning 2 orders of magnitude. We establish the existence of an energy-per-pulse threshold at which etching of the laser-modified zones becomes highly(More)
To our knowledge only one processing formula for silver-halide sensitized gelatin (SHSG) derived from Agfa-Gevaert holographic plates has been published in the current literature, which is apparently a result of the extremely high degree of hardening of the gelatin emulsion. We propose a modified processing formula for SHSG derived from Agfa-Gevaert plates.(More)
We identify two states of stress induced in waveguides fabricated by femtosecond lasers in fused silica and show how they can be relieved by annealing. In-plane stress and stress concentration are revealed through birefringence and loss measurements. Another kind of laser-induced stress appears in the form of swelling of the glass surface when waveguides(More)
Holographic stars fabricated on DuPont's holographic recording film HRF 600X010 by the use of He-Ne laser light are demonstrated. The stars operate with plane waves, the transmitted portions of the input beams are used at the corresponding outputs, and the gratings are in the volume regime of diffraction. Multiple exposure based on the Bragg degeneracy(More)
Novel designs of polarization devices based on Bragg reflector waveguides in a high index contrast silicon-on-insulator (SOI) platform have been proposed. Brewster angle condition is incorporated in the periodic structures. Numerical simulations with a 3D semivectorial beam propagation method demonstrate the device performance as TE mode polarizer with high(More)
We demonstrate a shot-to-shot reduction in the threshold laser intensity for ionization of bulk glasses illuminated by intense femtosecond pulses. For SiO2 the threshold change serves as positive feedback reenforcing the process that produced it. This constitutes a memory in nonlinear ionization of the material. The threshold change saturates with the(More)