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A simple reflection technique proposed by Teng and Man [Appl. Phys. Lett. 56, 1734 (1990)] as well as independently by Schildkraut [Appl. Opt. 29, 2839 (1990)] for measuring the electro-optic coefficients of poled polymer films is applied to measure the r33 values of both z-cut lithium niobate crystal and diazo-dye-substituted polymer films. The measured r33 value of the lithium niobate crystal is in excellent agreement with the known value, and the observed r33 values of the poled polymer films agree well with those predicted from the second-harmonic-generation measurements.

A vertically stacked directional coupler incorporating electro-optic poled polymer was fabricated by spin coating, photolithography, and reactive ion etching processes, based on the fabrication technique used for polymeric single-mode channel waveguides. Vertically coupled operation at 1.3 μm have been achieved between two stacked channels which were kept 3.5–5 μm apart by a narrow cladding layer. The intensity modulation has been clearly demonstrated in the coupler with electrodes when a voltage is applied at 10 kHz between them.

The unsteady-state thermal conduction process in single-mode optical fiber was studied theoretically with the explicit finite-difference method. We assumed that the vitreous silica optical fiber underwent pyrolysis at elevated temperatures to formSiOx(x~1). We also proposed a model in which the optical absorption coefficient of the core layer increased with increasing molar concentration ofSiOx. The core-center temperature changed suddenly and reached over3×104 K when a 1.064-μm laser power of 2 W was input into a short core layer of 40 μm length, which was heated at 2923 K. This thermal wave, that is, a fiber fuse, increased in size and propagated toward the light source at a rate of about 0.54 m/s. The calculated propagation velocity of the fiber fuse was in agreement with the experimental value. Moreover, the average temperature of the radiated region of the core layer gradually approached a temperature of about 5700 K. It was found that the final average temperature was close to the experimentally reported values.

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