Leslie James Button

Pump-mediated inhomogeneous effects in EDFAs and their impact on gain spectral modeling

Summary form only given. Recently it has been shown that small changes in pump wavelength within the 980-nm pump band change the shape of the gain spectrum of erbium-doped fiber amplifiers (EDFAs). These gain variations can be as large as 3 dB in a typical line amplifier and cannot be explained by the well known homogeneous model for EDFAs. Pump-induced gain changes must be accounted for in multiwavelength amplifiers and systems operating over the pump-wavelength-sensitive short-wavelength portion of the erbium gain band. In this paper, we compare the impact of pump-mediated inhomogeneities on the gain spectra of EDFAs pumped in the 1480- and 980-nm pump bands. We find that the shape of the EDFA gain spectrum is less affected by changes in pump wavelength in the 1480-nm band, and show that in both cases the dynamic gain tilt function (DGTF) is relatively insensitive to changes in pump wavelength. The latter indicates that inversion-induced gain changes can be predicted from a (measured) DGTF despite pump band and some signal band inhomogeneities. We present fluorescence line narrowing measurements that explain these results and suggest a physical mechanism for 980-nm band pump-mediated inhomogeneities.

Alumina barrier layers on LCD glass

Abstract Effective diffusion coefficients, D e , for the movement of sodium from an LCD glass into a sputtered alumina barrier layer have been determined. Secondary ion mass spectrometry analysis was used to measure sodium concentrations in 100 nm thick alumina films on soda lime glass at 520°C and for similar films on alkaline earth boroaluminosilicate glass at 650°C. Calculated values of D e are compared with extrapolated values of the diffusion coefficient, D , for sodium in polycrystalline alumina. The agreement is inconsistent. This is explained in terms of the countercurrent of hydrogen ions needed to maintain charge neutrality when a sodium ion moves out of the glass into the alumina film.

Comparison of Nd3+-doped glasses for amplification in the 1300-nm region

Excited-state-absorption and stimulated-emission cross-section spectra have been measured in the 1300-nm region for a wide variety of Nd3+-doped glass compositions. The results indicate that fluoroberyllates are the best choice for fiber amplifiers in the 1300-nm optical communications window. Model calculations predict a gain spectrum peaked at 1314 nm with useful gain extending from 1304 to 1370 nm when amplified spontaneous emission is neglected.

P-131: Three-Dimensional Modeling of Liquid Crystal Pixels

In this paper an approach to modeling the optics of liquid crystal (LC) pixels or sub-pixels in a liquid crystal display (LCD) panel in three dimensions is described. A commercial finite element modeling package (ANSYS) was chosen as the primary platform for this solving the director electrostatics problem. Within ANSYS, the pixel geometry and electrical boundary conditions can be defined and the electrostatic field and the LC orientation subsequently determined. The algorithm crucially depends on a scaling of the LC material properties to lower the aspect ratio of the problem. This information is then used to calculate optical transmission through the pixel using a ray tracing algorithm.