High-Bandwidth Zero-Biased Waveguide-Integrated p-n Homojunction Graphene Photodetectors on Silicon for a Wavelength Band of 1.55 m and Beyond

The p-n homojunction graphene photodetectors (GPDs) based on the photothermoelectric (PTE) effect have drawn much attention for featuring zero-bias operation (i.e., zero dark current) with a bandwidth of tens of GHz. However, most waveguide-integrated GPDs were demonstrated for the 1.55 mu m wavelength band. Here, we realize high-performance silicon waveguide integrated GPDs enabling efficient light absorption at both wavelength bands of 1.55 and 2 mu m. The broadband operation of the present PTE GPDs is analyzed theoretically and experimentally. When operating at 1.55 mu m, the GPD typically exhibits a responsivity of similar to 2.81 V/W and a 3 dB bandwidth of >40 GHz (setup-limited) under zero bias. When the GPDs operate at 2 mu m under zero bias, the responsivity is about 2.78-4 V/W and the 3 dB bandwidth is >22 GHz (setup-limited). The measured linear dynamic range is over 24 dB for both wavelength bands of 1.55 and 2 mu m. The present high-performance waveguide-integrated GPD provides a promising option for the applications of silicon photonics beyond 1.55 mu m, such as optical communications, photonics sending, etc.