Etching of low loss mirrors for photonic ICs

The requirements for etching low loss mirrors and the dry etching techniques used for realizing these mirrors in photonic devices are reviewed. The effect of carbon dioxide and nitrous oxide additions to CH ₄/H₂ on the etch characteristics of double heterostructure layers is discussed. Vertical mirror profiles were obtained by using a CO₂ based etch process. Parabolic mirror elements having 1.2 dB loss were etched in an integrated InGaAsP/InP demultiplexer by using a CH₄/H₂/CO₂ reactive ion etching process. Loading effects were found to be dominant in methane/hydrogen based processes and were found to affect verticality of the quaternary layers