16:30 〜 16:45
▼ [11p-S421-11] Control of absorption properties of MEMS terahertz bolometers using metamaterials
キーワード：Terahertz, Metamaterial
We proposed a room-temperature operated, all electrically driving and detecting, sensitive and fast thermometer structure using a doubly clamped microelectromechanical (MEMS) resonator for bolometer applications. When a heating power is applied to a NiCr terahertz (THz) absorber film deposited on the MEMS beam surface, internal thermal stress is generated in the beam, leading to a reduction in the resonance frequency. The MEMS detects the shift in the resonance frequency caused by heating and works as a very sensitive thermometer. The NiCr absorber has a broadband absorption spectrum and is good for spectroscopy. However, since its absorption efficiency is only ~20 %, it is not suitable for THz imaging applications, in which illumination sources usually have fixed, narrowband emission spectra.
To solve this problem, we propose to use metamaterials which have a metal-insulator-metal (MIM) structure with rectangular patch patterns. The metamaterial absorber consists of an array of gold rectangular patches, a SiO2 insulation layer (thickness = h), and a bottom gold ground plane. The typical size of each rectangular patch was 23 μm×8 μm. The polarization of the incident light was set to be along the direction parallel to its long-side. We varied the thickness of the SiO2 insulation film, h, from 600 nm to 1400 nm. At around 3 THz, the maximum absorption reaches 88% when h = 1400 nm. The observed absorption spectrum was in good agreement with theory. The present metamaterial absorber has achieved narrowband, large absorption, which is suitable for THz imaging.
To solve this problem, we propose to use metamaterials which have a metal-insulator-metal (MIM) structure with rectangular patch patterns. The metamaterial absorber consists of an array of gold rectangular patches, a SiO2 insulation layer (thickness = h), and a bottom gold ground plane. The typical size of each rectangular patch was 23 μm×8 μm. The polarization of the incident light was set to be along the direction parallel to its long-side. We varied the thickness of the SiO2 insulation film, h, from 600 nm to 1400 nm. At around 3 THz, the maximum absorption reaches 88% when h = 1400 nm. The observed absorption spectrum was in good agreement with theory. The present metamaterial absorber has achieved narrowband, large absorption, which is suitable for THz imaging.