GaAs optical waveguide structures at 10.6-microm wavelength

A comparison of GaAs/n(+)GaAs, GaAs/GaAsP, and GaAs/AlGaAs waveguide structures is presented. Their fabrication processes and their transmission properties at 10.6-microm wavelength are described. The loss due to the free carrier absorption of the substrate is analyzed. Experimentally, an attenuation rate of 2 dB/cm in a single mode (~7 microm) GaAs/GaAsp waveguide with a maximum dimension of the order of 7 cm has been achieved.