White metal-like omnidirectional mirror from porous silicon dielectric multilayers

We report the design and fabrication of the complete visible range omnidirectional mirror, with a dielectric multilayered structure based on porous silicon (PS). The refractive index profile consisted of Bragg type chirped layers with an increasing thicknesses modulated by a potential envelop function f(x)=Cxk. The omnidirectional photonic band gap (OPBG) was measured from 396 to 805 nm, with more than 95% of the reflectivity, for 8° and 68°. The theoretical simulations based on the transfer matrix method along with a photographic sequence of the sample confirmed the OPBG for higher incident angles. It was enhanced by a factor of 19 as compared to the last reported visible region OPBG by PS dielectric multilayered structure.