Experimental Investigation Of MBE GaAs Rib Waveguides At 10.6 μm

GaAs is a very attractive material for use at the 10.6-μm wavelength of the CO2 laser, and very little work has been done at this wavelength. This paper discusses recent investigations with n/n+-GaAs rib waveguides fabricated by molecular beam epitaxy and reactive ion etching. A simple effective index method of analysis was performed to predict the propagation constants of the bound modes. Comparison with other methods of analysis has shown this method to be fairly accurate for the geometries used. The prism-coupling technique was modified for rib waveguides. Experimental intensity curves as a function of incident angle (Θ) correlated well with the theoretical lower order modes.