Wavelength sensitivity in directional couplers

Measured and calculated crosstalk ratios as a function of wavelength are compared for proton exchanged and annealed LiNbO₃ directional couplers at λ=1550 nm. The analytical technique employed models the experimentally determined wavelength sensitivities reasonably well. The analytical technique is further used to predict comparable functions for titanium indiffused couplers, and these results are compared to other calculations taken from the literature. No significant difference in sensitivity is noted between the two waveguide forming techniques