▎ 摘　　要

NOVELTY - The filter device (100) comprises a substrate (110). A graphene layer (120) is formed on the substrate. The metal plates (130) are formed on the Graphene layer to form one slit (140). A gate voltage (160) adjusting unit is used for adjusting a gate voltage applied to the filter device. A portion of the Graphene layer is exposed through the slit. The graphene layer is electrically doped and the gate voltage is controlled in reference to the Fermi level and plasmon resonance wavelength of the graphene layer is adjusted. The Fermi level of the graphene layer is adjusted as the gate voltage is adjusted. The light incident on the filter device is light in the mid-infrared region, and as the gate voltage is adjusted. USE - Filter device for transmitting the incident light for measuring the atmospheric gas in the environments. ADVANTAGE - The filter device can replace expensive lasers such as quantum cascade laser (QCL) or sensors with low sensitivity and accuracy, which are inexpensive, and can be implemented in a small size, and can be implemented to enable sensing in a broadband mid-infrared region with high sensitivity and accuracy. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method of manufacturing a filter device that transmits incident light. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a filter device capable of adjusting transmittance of incident light by adjusting a gate voltage. Filter device (100) Substrate (110) Graphene layer (120) Metal plates (130) Slit (140) Gate voltage (160)