Abstract

Progress in establishing a large second-order nonlinearity [χ⁽²⁾] in silica fibers is reviewed. A χ⁽²⁾ has been induced in germano- silicate fibers by poling the fiber with a large applied electric field [10⁶ - 10⁷ V/cm] and either an elevated temperature [~100 - 200°C] or UV irradiation [193 nm or 248 nm]. Nonlinearities approaching that of LiNbO₃ have been reported. Once the nonlinearity is established, the field can be removed leaving a permanent effect. Comparison of measurements of second-harmonic generation (SHG) coefficients and of the linear electro-optic effect demonstrate that the nonlinearity is electronic in origin.

© 1996 Optical Society of America