级联χ^(2)过程产生高量值高阶非线性相移

The generation of high-order nonlinear phase shifts by cascaded χ^(2) processes

基于位相失配三倍频 (Δk≠ 0 )转换 ,构建了产生高阶非线性相移的 χ( 2 ) 级联非线性过程 .此过程不涉及三阶等其他非线性效应 ,仅表现为纯的五阶非线性 ,所感应的非线性相移正比于I2 .进一步的数值计算研究表明 χ( 2 ) 级联五阶非线性相移不仅符号可控 ,而且具有丰富的饱和特性 ,其量值远高于 χ( 2 )

Based on the phase mismatched frequency tripling, a special configuration is proposed to produce high order nonlinear phase shifts. In this process, the fifth order nonlinearity dominates, which is proportional to the square of input fundamental intensity in the limit of large phase mismatch, and no pump depletion in the first crystal. Compared with conventional cascaded χ (2) nonlinearity, theoretical study and numerical simulations show that this specific high order nonlinear phase shift can be much larger in magnitude with a controllable sign and a rich saturable feature.