Modeling of Ultrawidely Tunable Vertical CavityAir-Gap Filters and VCSELs

Abstract

Tunable vertical cavity devices including an air-gapintegrated in the cavity have been designed, fabricated, andinvestigated. The ultrawide wavelength tuning is realized by mi-cromechanical actuation of Bragg mirror membranes. Based onoptical and mechanical model calculations, the air-gap filters andvertical cavity surface emitting lasers (VCSELs) are designed forinvestigating mainly the optical tuning efficiency. In our research,we focus on two different mirror material systems, dielectricSi3N4SiO2and InP/air-gap Bragg mirrors and on two tuningconcepts, respectively. For the dielectric mirrors, continuoustuning is achieved by thermal actuation of theSi3N4SiO2mirror membranes, and for InP/air-gap mirrors, electrostaticactuation of the InP membranes is used. To verify the opticaland mechanical simulations, InP/air-gap filters are characterizedby measuring reflectance spectra and the tuning behavior. Themeasured results agree with the simulations used to optimize themicromechanical and optical characteristics of air-gap filters andVCSELs for optical communication applications.