Optimum operating point of electroabsorption modulators for 10-Gbit/s transmission

The performance of l0-Gbit/s transmission systems that use electroabsorption modulators is a strong function of the modulator chirp, average transmitted optical power and optical extinction ratio. The chirp of an electroabsorption modulator depends on the electro-optic properties of the absorption layer in the p-i-n waveguide. As the reverse bias voltage is decreased over the operating range of the device, the a-parameter, which quantifies the modulator chirp, typically decreases and is either positive or changes from positive to negative. To determine the optimum bias and modulation voltages, a model for the electroabsorption modulator is used that is based on measured results for the dependence of the absorption and on applied voltage