Optical waveguide parabolic coupling horns

Abstract

We propose parabolic-shaped coupling horns to provide adiabatic transition regions between wide- and narrow-channel optical waveguides. The parabolic shape is shown to derive from a simple ray model of channel propagation and is consistent with diffraction theory in the wide-channel limit. An approximate mode dispersion theory is used to convert the criteria into a horn design for indiffused channel waveguides. Experimental horn transmission measurements of nearly 90% are reported for transitions from 25 μm to 8, 6, and 4 μm in Ti:LiNbO3 waveguides at 0.6328 μm.