▎ 摘　　要

Little is known about the impact of different locations of a graphene upon absorption of photons on the photocurrent generation and how to precisely calibrate photoelectric properties of graphene photodetectors. We propose a system of targeted stimulus and synchronized detection for photoelectric properties of graphene photodetectors. Precision of the targeted stimulus of the system can be adjusted at the nano-scale. The system was used to calibrate photoelectric properties of a graphene photodetector and investigate photocurrent generation upon absorption of the photons at different positions of the graphene. This study not only offers a general way to investigate and deeply understand the photoelectric properties of the graphene, but also provides a guide for designing the graphene photodetector with higher performance. (C) 2018 Optical Society of America.