“…The dip in the normalized transmittance curve represents the lowest feasible value of transmittance at the focal point. 56,57 A valley in the open aperture curve, as depicted in Fig. 12b, confirms the presence of strong reverse saturable absorption (RSA), as the positive nonlinear absorption of the molecule in the excited state is comparatively higher than the absorption in the ground state, which ensures the strong RSA effect.…”