Emulator of harmonic distortion of bias port of the Mach-Zehnder intensity modulator

Jiri Svarny

   The paper deals with the design of an analog circuit to substitute the role of a real intensity Mach-Zehnder modulator for the preliminary tuning of bias controllers. The proposed circuit has similar harmonic distortion as an electro-optic modulator biased around the quadrature operating point. The designed device utilizes a shaping circuit based on a differential pair of bipolar junction transistors. The harmonic distortion of both the Mach-Zehnder intensity modulator and the differential amplifier are analysed. A method to design the emulating circuit of desired features is described and explained and a the comparison of the measured results to the theory is presented.

Keywords: circuit emulation, electro-optic modulator, harmonic analysis, harmonic distortion, intensity modulation

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