Thermal and optical nonlinearity due to broadened femtosecond nJ pulses at high repetition rate

In an experiment, the contribution to the optical nonlinear effects mainly depends upon the characteristics of the pump pulse such as the repetition rate and the pulse duration. Under high repetition rate (HRR) laser excitation, significant thermal effects are also present along with the optical effects even with femtosecond nJ pulse energies. In this work, these effects have been distinguished by the technique of Z-scan by varying the pump pulse duration.