Low-loss GaAs optical waveguides formed by lateral epitaxial growth over oxide

We report the successful demonstration of a new type of single-mode semiconductor waveguide, an oxide-confined optical waveguide, that has lower loss and should have a smaller allowable bend radius than previously reported structures. The waveguides are formed by a new technique of lateral epitaxial growth of single-crystal GaAs over an SiO2 film. Rib waveguides formed on these epitaxial layers have SiO2 as the lower confining layer and thus have better confinement than comparable all-semiconductor structures. Losses of only 2.3 dB/cm (0.54 cm−1) have been measured at 1.06 mm.