Performance enhancement of an ultrafast graphene photodetector via simultaneous two-mode absorption in a hybrid plasmonic waveguide

An ultrafast, compact, zero-biased, and complementary metal-oxide semiconductor-compatible graphene photodetector (PD) based on a silicon-on-insulator hybrid plasmonic waveguide (HPWG) is proposed. Lumerical MODE solver is employed to investigate the modal characteristics of TM-polarized modes in the HPWG composing the PD. It is shown that the input light can be completely coupled into the photonic-like and plasmonic-like fundamental TM modes at the PD section. These two modes are exploited together in the photodetection process to enhance the PD performance. A rigorous analysis is performed in order to extract the optoelectronic characteristics of the single-layer graphene (SLG) used in the proposed structure. Lumerical 3D-FDTD solver is then employed to quantify the light interaction of the two aforementioned optical modes with the SLG. With a proper design at a wavelength of 1550 nm, the PD voltage responsivity reaches 2.8 WW, and the photocurrent responsivity is obtained as 18.5 mA/W, while the corresponding absorption length is kept below 8 mu m and the noise equivalent power is limited to 3.7 pW/root(Hz) over bar. Moreover, as the PD operates under zero bias, its photoresponse is predominated by the photothermoelectric mechanism, exhibiting a bandwidth that exceeds 180 GHz while avoiding the dark current. (C) 2022 Optica Publishing Group

Automated summary

An ultrafast, compact, zero-biased, and CMOS-compatible graphene photodetector based on a hybrid plasmonic waveguide is proposed. The photodetector utilizes photonic and plasmonic modes in the waveguide to enhance the detection performance. The results demonstrate high voltage responsivity and photocurrent responsivity at a wavelength of 1550 nm.