High-responsivity and high-bandwidth uni-traveling carrier photodetectors for ultra-high-speed transmission networks

With the rise of cloud computing, big data, and mobile internet, there is an increasing demand in information society for higher communication bandwidth and speed. There is an urgent need to conduct research on the next generation of ultra-high-speed transmission networks, with high-speed photodetectors being key components. We designed and fabricated a high responsivity, high bandwidth, and high output power edge-coupled Uni-Traveling Carrier Photodetector (UTC-PD). This paper details the structural design, experimental fabrication, and test results of a 1550nm wavelength InP-based edge-coupled UTC-PD. To achieve high responsivity and bandwidth simultaneously, we optimized the thickness of the absorption and collection layers. The device was fabricated using metal organic chemical vapor deposition and contact lithography techniques. The test results show that at a wavelength of 1550nm, the UTC-PD achieves a photoresponse of 0.49A/W (without anti-reflection coating). We conducted high-frequency performance testing of the photodetector using a vector network analyzer. Photodetectors of the same size exhibited uniform bandwidth performance, with a maximum bandwidth reaching up to 34.1GHz. At an optical current of 2.85mA, the photodetector exhibits RF output powers of 247uW @ 1GHz and 26.8uW @ 91GHz, with a reduction of 8.96dB within the 90GHz frequency range. This high responsivity, high bandwidth, and high output power photodetector could offer promising chip options for upcoming ultra-high-speed optical transmission networks.