Thermal poling of glass modified by femtosecond irradiation

Thermal poling of silica glass modified by femtosecond laser irradiation is demonstrated. Increase of second-harmonic generation in the irradiated regions is observed. This enhancement is interpreted in terms of structural modifications in silica glass that make the poling process more efficient. Evidence of a change in the distribution of the electrostatic field frozen in glass during poling is obtained. This technique is used for (2) grating fabrication

Femtosecond direct writing of embedded photonic structures

In the last few years, femtosecond lasers have proven to be of great utility for micromachining within the bulk of transparent materials and this processing technique has attracted much attention due to its simplicity compared to lithographic methods and its ability to write in three-dimensions. When an intense femtosecond laser pulse is tightly focused into transparent material, high-order non-linear absorption allows the energy to be deposited predominantly within the focal volume producing a local permanent refractive index modification

Isotope separation by magnetic activation and separation

A method for separation of isotopes includes vaporizing a sample having two or more isotopes of the same element. A stream of atoms is generated from the vaporized sample. One or more light waves are applied to the stream. The one or more light waves are tuned to prepare one or more specific isotopes in the flowing stream into a set of one or more magnetic states. A magnetic field is applied to the stream, deflecting atoms in the stream based on their magnetic states. Isotopes are collected based on their deflections (or lack of deflection).Board of Regents, University of Texas Syste

Fibre-optic cavities for the observation of single guided atoms

We investigate a variety of designs to use standard fibre technology for optical access to atoms trapped in miniaturised magnetic traps on the surface of silicon or glass substrates

Form birefringence and negative index change created by femtosecond direct writing in transparent materials

Although femtosecond lasers have proved to be of great utility for micromachining within bulk transparent materials, little is known about the fundamental physics that drive the process. Depending on the laser intensity delivered to the sample, any of three types of feature can be written into the glass. We observed that in the intermediate regime there is a correlation among the negative sign of the effective index change, the presence of anisotropic reflection, and birefringence. We propose a model that can explain all three principal characteristics. Results show that the local index change can be as high as 10-1

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Not AvailableAmong the available sources of cytoplasmic male sterility only the A1 source has so far been exploited for breeding commercial hybrids of pearl millet (Pennisetum glaucum (L.) R. Br.). The influence of this source was studied by comparing the combining ability of five pairs of lines that differ in their cytoplasmic source. The effect on the expression of the traits, though modified by environment, was significant. The manifestation of cytoplasmic effects on general combining ability (GCA) was different for various traits. In general, the A1 cytoplasm showed a positive influence on GCA estimates for plant height, grain yield, and a negative influence on days to flowering. The variable magnitude of cytoplasmic effects on the GCA of lines indicated that such effects were the result of interaction between cytoplasm and nuclear genes.Not Availabl

Birefringent Fresnel zone plates in silica fabricated by femtosecond laser machining

We demonstrate maskless, single-step fabrication of strongly birefringent Fresnel zone plates by focusing of femtosecond laser pulses deep within silica substrates. The process allows us to produce alternate zone rings directly by inducing a local refractive-index modification of the order of n~10-2 . The embedded zone plates shown in this Letter exhibit efficiencies that vary by as much as a factor of ~6 for orthogonal polarizations. Focal lengths of primary and secondary foci are shown to compare well with theory

Possibility of single-atom detection on a chip

We investigate the optical detection of single atoms held in a microscopic atom trap close to a surface. Laser light is guided by optical fibers or optical microstructures via the atom to a photodetector. Our results suggest that with present-day technology microcavities can be built around the atom with sufficiently high finesse to permit unambiguous detection of a single atom in the trap with 10 µs of integration. We compare resonant and nonresonant detection schemes and discuss the requirements for detecting an atom without causing it to undergo spontaneous emission