Long-Wavelength Oxide Vertical-Cavity Surface Emitting Lasers

This proposal describes an experimental program to determine the feasibility of fabricating long-wavelength (>1.3um) oxide vertical-cavity surface-emitting lasers (VCSELs). It addresses the two most inhibiting difficulties in fabricating practical long-wavelength VCSELs: 1) Use of oxidized layers in the bottom mirror results in a mirror thickness reduction from ~7um to <2um. 2) Implementation of a current aperture defined by oxidation should minimize required current densities as in shorter-wavelength oxide VCSELs. Phase I targets 1.3-1.55 um wavelengths, although the techniques are also valid for longer wavelengths. Use of InP substrates allows growth of standard 1.3-1.55 um laser active regions. Central to the program is investigation of "wet oxidation" of AlAsSb layers lattice matched to InP: required temperatures, oxidation rates, possible changes in material volume, robustness, effect on active material, etc. Phase I will fabricate simple test structures with a wide range of parameters, test them, and determine whether the process can produce practical long-wavelength VCSELs. An optional task is to fabricate and characterize actual VCSELs using the proposed process.