Design and Demonstration of High-Speed and High-Power Traveling-Wave Germanium Photodetector

Traveling-wave photodetector (TWPD) with output photocurrent of over 127.5 mA and 3-dB bandwidth of 36.8 GHz at 1 mA is demonstrated. Under the photocurrent of 40 mA, the 8-PD TWPD shows a bandwidth of 32.3 GHz and realizes clear 50 Gb/s open eye diagram in such a high-power situation. Based on reflection coefficients and equivalent circuit, the current-dependent phenomenon of PD junction capacitance and its influence on high-speed behavior of TWPD at high-power mode is proposed and analyzed. The detailed analysis and experimental demonstration of this work will provide effective guidance for the design and manufacture of high-performance TWPD.