We report the design and fabrication of an optimized antireflecting structure with the maximum transmittance (T-max) and minimum reflectivity (R-min), based on a porous silicon dielectric multilayer (PS-DM). The structures consist of 50 layers of equal thicknesses with an increasing refractive index profile, n(z) similar to z(k). Numerical results based on the transfer matrix method, along with an average spectral analysis, were used to compute a certain range of thicknesses (with the optimal thickness of 235 nm) to obtain similar optical response (T-max and R-min). The average reflectivity spectrum of a PS-DM structure in the proposed optimal range was experimentally measured to be 1.3% from 300 to 1100 nm. Such structures can be used to enhance the efficiency of silicon solar cells and optoelectronic devices. (C) 2014 Elsevier B.V. All rights reserved.