Abstract

Growth of second harmonic (SH) from 1064-nm light in optical fibers up to final efficiencies of around 1 % has been observed by several workers.^1-3 We believe we are the first² to identify the mechanism for this unusual phenomenon in terms of an optically written defect grating in the fiber with a χ⁽²⁾ modulated at the phase mismatch period between pump and SH light. The orientation of the χ⁽²⁾ grating is determined by the periodically reversing internal dc field that arises via a third-order nonlinear interaction between pump and SH light.³

© 1988 Optical Society of America