Pure quartic spatiotemporal solitons in graded-index media

We investigate the formation of spatiotemporal solitons in waveguides with a parabolic refractive index and quartic chromatic dispersion. Using both variational methods and full 3D simulations, we demonstrate that fourth-order dispersion enhances soliton stability, preventing spatiotemporal collapse. Pure quartic solitons maintain stability over a broader energy range compared to solitons formed by second-order dispersion.