Investigation of tunnel excitation of and emission from diffused optical waveguides

The tunnel emission coefficients of TE and TM waves from 14- and 3-mode diffused waveguides were investigated experimentally and theoretically for various thicknesses of a homogeneous gap between a coupling prism and the waveguide. A study was made of the extraction of radiation across wedge-shaped gaps. The efficiency of coupling in of radiation was determined as a function of the waveguide, prism, and gap parameters. Efficient (η ≈ 85%) tunnel coupling in of radiation into a diffused waveguide was achieved across a wedge-shaped gap.