Ricerc@Sapienza

The study of a pre-tunnel structure that filters the daylight has been carried out by means of 3D daylight simulation software. The 1:1 scale model of the tunnel and the pre-tunnel has been realized and two different sequences of filtering panels have been simulated. The first sequence reproduces the panels experimented in a previous study with a real scale model; the second sequence is aimed to optimize the filter effect, acting on the grid of the panels.

A highly selective filter is designed, working at 1.55 ?m and having a 3-dB bandwidth narrower than 0.4 nm, as is required in Dense Wavelength Division Multiplexed systems. Different solutions are proposed, involving photonic crystals made rectangular- or circular-section dielectric rods, or else of holes drilled in a dielectric bulk. The polarization and frequency selective properties are achieved by introducing a defect in the periodic structure. The device is studied by us- ing in-house codes implementing the full-wave Fourier Modal Method.