High-reflectivity lead-salt-based Bragg mirrors for the mid-infrared range

High-quality lead-salt-based Bragg mirror stacks were fabricated on BaF2 (1 11) substrates by molecular beam epitaxy. The mirrors consisted of Pb1 - x EuxTe quarter-wavelength layer pairs with 1 % and 6 % Eu content and mere d esigned for use in mid-infrared (MIR) vertical emitting devices with a PbTe active zone. Front theoretical simulations, we obtained the internal refle ctivity with incidence from an active resonator medium and the reflectivity spectra of Bragg/metal mirror combinations. For a 32-layer pair mirror, me measured a record stopband reflectivity for the MIR of over 99 % at 5.7 mu m, in excellent agreement with our calculations.