Optimum conditions in the attenuated total reflection technique.

In this paper the optimum condition for using the attenuated total reflection (ATR) technique is studied. In optimum conditions, the energy of an incident plane wave can be totally absorbed. The optimum condition can be realized by fabricating a localized thickness variation in the gap between a prism and a sample substrate with a point contact pressure.

Thickness measurement of ultrathin films on metal substrates using ATR.

By modifying the surface plasma mode on a bare metal surface with an ultrathin film deposited on the metal, we measured the film thickness by attenuated total reflection (ATR). Various factors causing measurement errors are estimated with numerical examples. As a result, for example, it is shown that for some thicknesses, the errors due to the real part of the complex refractive index of a metal substrate become extremely small.

Random-bend loss in single-mode and parabolic-index multimode optical fiber cables.

Excess losses of single-mode and multimode cabled optical fibers due to random bends of the Gaussian correlation function are discussed theoretically. By comparing theoretical results of various correlation functions to measured excess losses of the cabled fibers, it is verified that the correlation function of random bends of single-mode and multimode cabled fibers is estimated to be Gaussian. Using the estimated Gaussian correlation function, random-bend loss formulas of the single-mode and the graded-index multimode fiber cables are given.

Reduction of resonancelike peak in direct modulation due to carrier diffusion in injection laser.

It is shown theoretically that the relaxation oscillation in the direct modulation of the injection laser is reduced by transverse carrier diffusion when the stripe width is comparable to the carrier diffusion length. Modified rate equations are derived by considering the distribution of the light intensity, the carrier density, and the diffusion of the carrier. By small-signal analysis of the rate equations it is found that the height of the resonancelike peak in the modulation characteristics is a minimum when the transverse width in which both the light and the carriers are confined is around the diffusion length.