Efficient phase-matched down-conversion in highly dispersive 1D-PBG

Summary form only given. In the past years a lot of work has been devoted to the study of efficient second harmonic generation (SHG) in 1D periodic structures. We investigate on the properties of layered media in the framework of frequency downconversion (FDC). The major difference between SHG and FDC is related to bandwidth requirements due to the need of tunability of the FDCs. We will describe general designing rules to obtain phase-matched FDC in a periodically layered material. Our method is based on the use of a multi-layer unit cell and applies even for highly dispersive materials. We analysed a AlGaAs based waveguide with superimposed longitudinal PBG structure obtained by periodic deep etching. To evaluate phase-matching we considered an equivalent 1D structure consisting of a stack of N elementary cells.