OPTICAL RESPONSE OF PORUS SILICON AND POROUS ALUMINA HYBRID STRUCTURES

R. URTEAGA; L. FORZANI; L. CENCHA; R.R. KOROPECKI

Tarragona

Conferencia; 10th International Conference PSST2016; 2016

PSST

In this work, we evaluate theoretically and experimentally the optical response of structures that integrate poroussilicon and porous alumina to form a multilayered hybrid structure. We perform a rational design of the optimalsequence necessary to produce a high transmission and selective filter. The combination of these two porous materialscan be used to exploit the distinguishing features of each material, i.e. high transparency of the alumina andhigh refractive index contrast that can be achieved with porous silicon. We build hybrid microcavities with a centraldefect of porous alumina which is placed between two porous silicon distributed Bragg reflectors. In this waywe construct a Fabry-Perot resonator with high reflectivity and low absorption that improves the finesse of thefilter respect to a microcavity constructed only with porous silicon. We also explore a simpler design in which oneof the Bragg reflectors is replaced by the aluminium that remains bound to the alumina after its fabrication. Wetheoretically explore the potential of the proposal and its limitations when considering a possible roughness of thelayers. We found that a microcavity made completely in porous silicon shows a limit in the finesse that can beachieved in the visible range mainly because its absorption. This limitation is overcome in the hybrid scheme, beingthe roughness of the layers the factor that determines the ultimate finesse. Q factors of 180 are obtained formicrocavities supported on aluminum and Q =240 for microcavities with double Bragg reflectors in 700nm.