Low-voltage traveling-wave electroabsorption modulator

Electroabsorption modulators (EAM) based on the quantum-confined-Stark QCS) effect have attracted a lot of interest in optical fiber communication due to their integrability with lasers, high extinction ratios and low chirp. At high frequency, the performance of conventional lump-electrode EAMs is limited by the total parasitic capacitance of the device, thus the device length can not be increased to improve the extinction ratio and saturation power. Based on the distributed effects, traveling-wave EA modulators (TWEAM) have been proposed to eliminate the lumped-element limits. In this paper, the practical issues of designing TWEAM for low-driving-voltage, high-speed and high-power operation are discussed.