Effect of poling conditions on second-harmonic generation in fused silica

Optical creation and erasure of the linear electrooptical effect in silica fiber

We study the creation and erasure of the linear electrooptical effect in silicate fibers by optical poling. Carriers are released by exposure to green light and displaced with simultaneous application of an internal dc field. The second order nonlinear coefficient induced grows with poling bias. The field recorded (~10⁸ V/m) is comparable to that obtained through classical thermal poling of fibers. In the regime studied here, the second-order nonlinearity induced (~0.06 pm/V) is limited by the field applied during poling (1.2 × 10⁸ V/m). Optical erasure with high-power green light alone is very efficient. The dynamics of the writing and erasing process is discussed, and the two dimensional (2D) field distribution across the fiber is simulated.

Study of thermally poled fibers with a two-dimensional model

A two-dimensional (2D) numerical model is implemented to describe the movement of ions under thermal poling for the specific case of optical fibers. Three types of cations are considered (representing Na(+), Li(+) and H3O(+)) of different mobility values. A cross-sectional map of the carrier concentration is obtained as a function of time. The role of the various cations is investigated. The assumptions of the model are validated by comparing the predictions to experimental data of the time evolution of the nonlinearity induced. A variational analysis of poling parameters including temperature, poling voltage, sign of the bias potential and initial ionic concentrations is performed for a particular fiber geometry. The analysis allows identifying the impact of these parameters on the induced second-order nonlinearity in poled fibers.