Direct measurement of bend-induced mode deformation in large-mode-area fibers.

In 1976 Marcuse developed an equivalent index model to predict the effects of bending in waveguides, and predicted deformation of the spatial modes in bent optical fibers. Perturbative approaches have been previously applied and tested to predict the behavior of single- and few-moded-fibers. However, much more significant mode deformation has been predicted for large-mode-area fibers than for single- or few-moded-fibers. In this paper, the spatial profiles of modes deformed by bending in large-mode-area fibers are measured for the first time. A finite difference method employing the equivalent index model is used to calculate the modes of the helical fiber, which show an offset that is twice as large as that predicted for single-mode fiber, and mode compression that is five times greater. These calculated results are compared to the experimental data, yielding significantly better agreement than previous perturbative approaches.

Co-sputtered SiC + Ag nanomixtures as visible wavelength negative index metamaterials.

The fabrication and characterization of a novel metamaterial that shows negative index in the visible (blue) is reported. The real part of the negative index of this metamaterial at 405 nm, comprising co-sputtered SiC + Ag nanoparticle mixture on a glass substrate, is deduced from results of double Michelson interferometry setup which shows a negative phase delay. It is numerically verified that this metamaterial can yield near-field super-resolution imaging for both TE and TM polarizations.

Generalized ellipsometry for monoclinic absorbing materials: determination of optical constants of Cr columnar thin films.

Generalized spectroscopic ellipsometry is used to determine the form-induced birefringence and monoclinic optical constants of chromium columnar thin films. The slanted nanocolumns were deposited by glancing angle deposition under 85 degrees incidence and are tilted from the surface normal. Dichroism measured for wavelengths from 400 to 1000 nm renders the Cr nanocolumns monoclinic absorbing crystals with c axis along the nanocolumns axis, b axis parallel to the film interface, and 74.8 degrees monoclinic angle between a and c axes. The columnar thin film reveals anomalous optical dispersion, extreme birefringence, and strong dichroism and differs entirely from bulk chromium.