Mid-IR Meta-Lenses

In Phase I of this STTR program, Structured Materials Industries, Inc. (SMI) and Sandia National Laboratories (SNL) will demonstrated high-efficiency mid-IR metasurface flat optics. We will use Metalorganic Chemical Vapor Deposition (MOCVD) to grow Lead Telluride (PbTe) on Barium Fluoride (BaF2) substrates to construct flat meta-lenses equivalent of cylindrical and aspheric lenses for mid-IR imagers and cameras. PbTe is ideally suited for creating dielectric meta-atoms due to its exceptionally high refractive index exceeding 7. BaF2 was chosen as the substrate due to its low loss in thermal IR and low refractive index (n = 1.4). Additionally, BaF2 is very closely lattice matched to PbTe. The large index contrast between PbTe and BaF2 contributes to the ultra-thin profile of the meta-atoms. In Phase II, we will build on Phase I experience to refine individual layers suitable for passive optics and move onto multilayer structures using Pb(Te,Se,S)/Mg(Te,Se,S) with a focus on PbTe/MgTe structures. The advancement to multilayer designs of the meta-lenses provides larger phase shift and reduces the abbreviation related problems. We will also design focal length adjustable tandem meta-lens structures.