Abstract

Optical losses in dielectric waveguides constitute a serious limiting factor on their performance in optical devices. In particular, losses in the ternary compound Al_xGa_1-xAs are important because (a) low threshold GaAs double heterostructure (DH) lasers utilize a very narrow active region (~0.2 μm) with low optical confinement, so that a significant fraction of the optical energy is in the Al_xGa_1-xAs cladding region where there is no gain, and (b) the larger band-gap of Al_xGa_1-xAs makes this material an attractive candidate for passive interconnections between active GaAs devices in integrated optical circuits. Recently, attention has been focused on GaAs layer growth by molecular beam epitaxy (MBE) for the fabrication of lasers and other optical devices because of the inherent advantages of MBE for layer uniformity and thickness control. In this paper, it is demonstrated for the first time that Al_.1Ga_.9As waveguides can be fabricated by MBE with below-band-gap losses comparable to or less than the losses observed in similar waveguide structures grown by liquid phase epitaxy (LPE).

© 1976 Optical Society of America