Effect of intrinsic phase mismatch on linear modulator performance of the 1*2 directional coupler and Mach-Zehnder interferometer

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Abstract
The performance of 1*2 directional couplers and Mach-Zehnder interferometers as linear modulators is compared. Models describing the operation of each device, incorporating the intrinsic phase mismatch Delta beta /sub 0/ which is present in nonideal devices, are developed. Distributions of Delta beta /sub 0/ are obtained for each device and are shown to be independent of device type. Linear dynamic range and sensitivity measurements showing how Delta beta /sub 0/ affects performance agree with theory. The additional effect of the coupling coefficient in the 1*2 directional coupler is demonstrated. This information can be used to predict device yield when combined with the measured Delta beta /sub 0/ distributions.