2025/07/01 by Yulia Gulina, Yu. S. Gulina, J. Zhu +10
Physics and Astronomy · Engineering · #Laser-Matter Interactions and Applications #Nonlinear Optical Materials Studies #Advanced Fiber Laser Technologies
paper · pdf · doi:10.1134/s0021364025607055
The nonlinear interaction of 250-fs laser pulses at a wavelength of 1030 nm with polymethyl methacrylate is investigated using an optimized z -scan technique. It is shown that the mechanism of pulse attenuation for peak intensities below 0.65 TW/cm 2 can be described as four-photon absorption with the coefficient β 4 = (35 ± 5) cm 5 /TW 3 . The nonlinear refractive index n 2 = (7.6 ± 0.4) × 10 −4 cm 2 /TW and the critical power for the onset of self-focusing P cr = (1.42 ± 0.08) MW are determined and these results are used to demonstrate the correspondence between the calculated shift of the nonlinear focal point and the location of the laser-modified regions.