Figure 3.

(a) Schematic of a PGe microcavity reflector constituted of a Fabry–Perot layer cavity of low porosity (refractive index n_LP and thickness e_DL) sandwiched by two DBRs. The two DBRs are made of a pattern of low (60%) and high porosity (80%) layers with a refractive index n_LP and n_HP and a thickness e_LP and e_HP, respectively, and repeated in this case two times. (b) Calculated reflectance spectrum of the PGe microcavity reflector with values of 60% and 80% for the low and the high porosities, respectively.