High-power traveling-wave photodetector based on an aperiodically loaded open-circuit electrode

We demonstrate a four-stage silicon distributed traveling-wave photodetector (TWPD) whose input terminal is open-circuit so as to enhance the radio-frequency (RF) output power. In order to mitigate the bandwidth drop caused by the RF reflection at the open input terminal, photodetector (PD) units are aperiodically loaded on the TW electrode. With the aid of an equivalent circuit model, we optimize spacings between PD units and then improve the 3 dB bandwidth from 7 to 10 GHz. A good agreement between measurement and modeling is obtained. Thanks to the cancellation of the input termination impedance, maximum RF output powers of the device are 10.2 and 6.5 dBm at 5 and 10 GHz, respectively. The corresponding power conversion efficiencies are 7.0% and 3.2%.