Noda J, Fukuma M, Mikami O
Appl Opt. 1981 Jul 1;20(13):2284-90. doi: 10.1364/AO.20.002284.
Coupling characteristics for designing a LiNbO(3) directional coupler fabricated by Ti diffusion have been investigated with a modified WKB method. The present analysis is verified by comparing the refractive-index change in the Ti-diffused LiNbO(3) waveguide derived from direct measurement and coupling length calculation. Coupling length variations due to refractive-index change, diffusion length waveguide spacing, and wavelength are described. Tolerances in coupling length mismatch and propagation constant differences affecting cross talk of the directional coupler are discussed.
