Metal-clad waveguides for Pb-salt diode lasers

Pb-salt waveguides with a metal-clad layer are discussed. It is shown that for TE modes one can assume that E(y) = 0 at the metal-semiconductor boundary, while for TM modes the complex formalism should be used. It is also shown that lasers with a metal-clad waveguide should have only a small increase in their threshold current while operating in a TE mode and that they should operate in a TE mode since their TM modes generally have high threshold current.