  There are two main physical properties needed to fabricate 1D photonic
structures and form perfect photonic bandgaps: the quality of the thickness
periodicity and the refractive index of their components. Porous silicon (PS)
is a nano-structured material widely used to prepare 1D photonic crystals due
to the ease of tuning its porosity and its refractive index by changing the
fabrication conditions. Since the morphology of PS changes with porosity, the
determination of PS's refractive index is no easy task. To find the optical
properties of PS we can use different effective medium approximations (EMA). In
this work we propose a method to evaluate the performance of the refractive
index of PS layers to build photonic Bragg reflectors. Through a quality factor
we measure the agreement between theory and experiment and therein propose a
simple procedure to determine the usability of the refractive indices. We test
the obtained refractive indices in more complicated structures, such as a
broadband Vis-NIR mirror, and by means of a Merit function we find a good
agreement between theory and experiment. With this study we have proposed
quantitative parameters to evaluate the refractive index for PS Bragg
reflectors. This procedure could have an impact on the design and fabrication
of 1D photonic structures for different applications.
