Majlesi Journal of Electrical Engineering Numerical Study on Normalized Split-step Fourier Method and Fourth-order Runge-Kutta Method in Laser Pulses Generation by Use of Photonic Crystal Fibers Volume 17 (2023) Issue 3, September 2023 2024 02 03 Numerical Study on Normalized Split-step Fourier Method and Fourth-order Runge-Kutta Method in Laser Pulses Generation by Use of Photonic Crystal Fibers 10.30486/mjee.2023.1975390.1031 EN Ashkan Ghanbari Nano-photonic and Optoelectronic Research Laboratory (NOR Lab), Shahid Rajaee Teacher Training University, Tehran 16788-15811, Iran. Saeed Olyaee Department of Electrical Engineering, Shahid Rajaee Teacher Training University, Tehran 16788-15811, Iran. Journal Article 2024 02 03 In this work, we study the generation of ultrashort femtosecond laser pulses in photonic crystal fibers through the widely used symmetric split-step Fourier method (S-SSFM). The results are compared with the method of fourth-order Runge-Kutta method (RK4) as the most recognized and powerful method in the analysis of the evolution of ultrashort femtosecond laser pulses. The results show that although S-SSFM is a widely used method, its accuracy decreases for the selected relatively large step sizes of  in comparison with RK4. In contrast, the accuracy of the mentioned methods becomes closer to each other by selecting relatively small step sizes of .