Biomedical subjects

Nader A Issa

Publications and source records attributed to Nader A Issa.

3 recordsLinked to original sources

PubMed2004

High numerical aperture in multimode microstructured optical fibers.

Microstructured or "air-clad" fibers, with air holes surrounding a large core, have recently demonstrated much wider light-acceptance angles than conventional fibers. An original and accurate method is presented for determining the numerical aperture of such fibers using leaky modes. The dependence on length, wavelength, and various microstructure dimensions are evaluated for the first time for a class of fibers that exhibit exceptionally high numerical apertures. These results show excellent agreement with published measurements on similar fibers and verify that bridge thicknesses much smaller than the wavelength are required for high numerical apertures.

Journal Article↗

PubMed2004

Fabrication and study of microstructured optical fibers with elliptical holes.

We report the fabrication of what are believed to be the first microstructured optical fibers with uniformly oriented elliptical holes. A high degree of hole ellipticity is achieved with a simple technique that relies on hole deformation during fiber draw. Both form and stress-optic birefringence are characterized over a broad wavelength range. These measurements are in excellent agreement with numerical modeling and demonstrate a birefringence as high as 1.0 x 10(-4) at a wavelength of 850 nm.

Journal Article↗

PubMed2004

Small-core single-mode microstructured polymer optical fiber with large external diameter.

A preform sleeving technique is demonstrated that allows the fabrication of single-mode polymer microstructured fiber with the smallest core and hole dimensions yet reported to our knowledge. For a fixed triangular hole pattern a range of fibers is produced by adjustment to the operating conditions of the draw tower. Numerical modeling is carried out for one of the fibers produced with a 570-microm external diameter, a core diameter of 2.23 microm, an average hole diameter of 0.53 microm, and an average hole spacing of 1.38 microm. This fiber was shown to be endlessly single mode.

Journal Article↗