Dependence of the readout resolving on the thickness of nonlinear super-resolution thin films

In this work, light beam is simulated through nonlinear super-resolution films by the finite element method. The results indicate that the transmitted beam can be reshaped and the light spot can be smaller than the diffraction limit due to the reshaping effect of strong nonlinear saturatable absorption. However, the size of the transmitted light spot cannot be decreased continuously with the increase of the film thickness, and the light spot size then decreases with the increase of the film thickness. The simulated results mean that the carrier-to-noise-ratio first increases, and then decreases with the film thickness, and there is an optimum film thickness for the read-only nonlinear super-resolution optical disks, which is consistent with the reported experimental results.