Novel evanescent-coupled germanium electro-absorption modulator featuring monolithic integration with germanium p-i-n photodetector

We report a novel evanescent-coupled germanium (Ge) electro-absorption (EA) modulator with a small active area of 16 μm2 giving an extinction ratio of at least 10 dB for a wavelength range of 1580-1610 nm. The modulation efficiency of the modulator at this wavelength range was ~2 dB/V. In addition, monolithic integration of both evanescent-coupled Ge EA modulator and Ge p-i-n photodetector is demonstrated for the first time.