Robert R. Alfano

Bio: Robert R. Alfano is an academic researcher from City College of New York. The author has contributed to research in topics: Laser & Scattering. The author has an hindex of 86, co-authored 1252 publications receiving 33960 citations. Previous affiliations of Robert R. Alfano include New York Eye and Ear Infirmary & The Graduate Center, CUNY.

Emission in the Region 4000 to 7000 Å Via Four-Photon Coupling in Glass

Abstract: Four-photon stimulated scattering has been observed in borosilicate glass under high-power 5300-\AA{} picosecond-pulse excitation. Parametric emission is generated from 4000 to 7000 \AA{} from filaments formed in the glass, the wavelength depending on the emission angle.

Observation of Self-Phase Modulation and Small-Scale Filaments in Crystals and Glasses

Abstract: Frequency broadening and small-scale filaments were observed in calcite, quartz, sodium chloride, and several glasses under picosecond pulse excitation. The physical mechanism responsible for these processes is the change in refractive index resulting from electronic distortion.

Higher-order Poincaré sphere, stokes parameters, and the angular momentum of light

Abstract: A higher-order Poincare sphere and Stokes parameter representation of the higher-order states of polarization of vector vortex beams that includes radial and azimuthal polarized cylindrical vector beams is presented. The higher-order Poincare sphere is constructed by naturally extending the Jones vector basis of plane wave polarization in terms of optical spin angular momentum to the total optical angular momentum that includes higher dimensional orbital angular momentum. The salient properties of this representation are illustrated by its ability to describe the higher-order modes of optical fiber waveguides, more exotic vector beams, and a higher-order Pancharatnam-Berry geometric phase.

Remote-controllable, micro-scale device for use in in vivo medical diagnosis and/or treatment

Abstract: Remote-controllable, micro-scale, robotic device for use in diagnosing and/or treating abnormalities inside a human body in vivo. The device has a length from 0.1 mm to 10 mm and can be introduced into the body either from natural body openings or by injection into the blood stream. Once inside the body, the device can be guided to different locations in the body by an outside operator using radio controls and computer software. 2-dimensional image information and spectroscopic information (e.g., fluorescence, absorption, elastic scattering, Raman, etc.) gathered by the device inside the body are transmitted by video and radio signals to a computer located externally relative to the body. The transmitted information is processed, analyzed and displayed by the external computer for use by the outside operator. The outside operator can then make a diagnosis and, if applicable, instruct the device to render a treatment on the examined area. Such treatments include the ablation of tissue using lasers or the like and the binding of ruptured tissues together using chemical glue, UV cured epoxy materials or photochemical or photo-ionization techniques using near-infrared light to weld tissue from absorption at water bands.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Optical coherence tomography

Abstract: A technique called optical coherence tomography (OCT) has been developed for noninvasive cross-sectional imaging in biological systems. OCT uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and lateral spatial resolutions of a few micrometers and can detect reflected signals as small as approximately 10(-10) of the incident optical power. Tomographic imaging is demonstrated in vitro in the peripapillary area of the retina and in the coronary artery, two clinically relevant examples that are representative of transparent and turbid media, respectively.

Spintronics: Fundamentals and applications

Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

Sensitive measurement of optical nonlinearities using a single beam

Abstract: A sensitive single-beam technique for measuring both the nonlinear refractive index and nonlinear absorption coefficient for a wide variety of materials is reported. The authors describe the experimental details and present a comprehensive theoretical analysis including cases where nonlinear refraction is accompanied by nonlinear absorption. In these experiments, the transmittance of a sample is measured through a finite aperture in the far field as the sample is moved along the propagation path (z) of a focused Gaussian beam. The sign and magnitude of the nonlinear refraction are easily deduced from such a transmittance curve (Z-scan). Employing this technique, a sensitivity of better than lambda /300 wavefront distortion is achieved in n/sub 2/ measurements of BaF/sub 2/ using picosecond frequency-doubled Nd:YAG laser pulses. >