(1) Quantum Electronics Department, Faculty of Physics, Sofia University, 5 J. Bouchier blvd., 1164 Sofia, Bulgaria;(2) Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
Abstract:
Generation of a fifth harmonic by the cascading of two phase-matched third-order processes in a single centrosymmetric nonlinear medium with a focused fundamental beam is investigated theoretically. With the help of analytical and numerical investigations the optimized conditions for maximum conversion into the fifth harmonic are found. In general the optimal position of focusing depends on the values of the mismatches k1 and k2 for both steps of the third order cascading (++=3; 3++=5). It is shown that for best efficiency this method of fifth harmonic generation requires specially chosen k1,opt and k2,opt and focusing in the center of the nonlinear media. If the phase matching parameters are fixed and they deviate from the optimal values, then the optimal strength of focusing and position of the focus spot should be calculated according to the analysis presented here. PACS 42.65.-k; 42.65.Ky; 42.79.Nv