Performances of THz cameras with enhanced sensitivity in sub-terahertz region
Performances of THz cameras with enhanced sensitivity in sub-terahertz region
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亚太赫兹区域灵敏度增强的太赫兹相机性能
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发表时间：
2015
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通讯作者：
K. Kawase
中科院分区：
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作者：
N. Oda;T. Ishi;Seiji Kurashina;Takayuki Sudou;T. Morimoto;Masaru Miyoshi;Kohei Doi;Hideki Goto;Tokuhito Sasaki;G. Isoyama;R. Kato;A. Irizawa;K. Kawase
开发了在亚太赫兹区域具有增强灵敏度的非制冷微测辐射热计型 640x480 和 320x240 太赫兹 (THz) 焦平面阵列 (FPA)，并将其分别集成到 640x480 和 320x240 相机中。 THz-FPA中的像素具有这样的结构：对电磁波敏感的区域悬浮在读出集成电路(ROIC)上方。敏感区域顶部形成薄金属层，而ROIC表面形成厚金属层。由薄金属层和厚金属层组成的结构表现为光学腔。本文报道的 THz-FPA 具有改进的像素结构，通过在 ROIC 上形成厚的 SiN 层，其光腔长度比 NEC 之前的像素长几倍。扩展的光腔结构有利于探测较低频率的电磁波。因此，在亚太赫兹区域，尤其是 0.5-0.6 太赫兹区域，每像素最小可检测功率 (MDP) 提高了十倍。本文使用大阪大学开发的太赫兹自由电子激光器（FEL），介绍了具有改进像素结构的太赫兹-FPA 和具有先前像素结构的太赫兹-FPA 的 MDP 值的光谱频率依赖性。像素结构的修改将高灵敏度区域扩展到较低频率区域，例如亚太赫兹区域，太赫兹相机更宽的光谱覆盖范围无疑扩展了其适用性
Uncooled microbolometer-type 640x480 and 320x240 Terahertz (THz) focal plane arrays (FPAs) with enhanced sensitivity in sub-THz region are developed, and incorporated into 640x480 and 320x240 cameras, respectively. The pixel in the THz-FPA has such a structure that an area sensitive to electromagnetic wave is suspended above read-out integrated circuit (ROIC). A thin metallic layer is formed on the top of the sensitive area, while a thick metallic layer is formed on the surface of ROIC. The structure composed of the thin metallic layer and the thick metallic layer behaves as an optical cavity. The THz-FPAs reported in this paper have a modified pixel structure which has several times longer optical-cavity length than NEC’s previous pixel does, by forming a thick SiN layer on the ROIC. The extended optical-cavity structure is favorable for detecting electromagnetic wave with lower frequency. Consequently, the Minimum Detectable Power per pixel (MDP) is improved ten times in sub-THz region, especially 0.5-0.6 THz. This paper presents spectral frequency dependences of MDP values for THz-FPA with the modified pixel structure and THz-FPA with the previous pixel structure, using THz free electron laser (FEL) developed by Osaka University. The modification of pixel structure extends high sensitivity region to lower frequency region, such as sub-THz region, and the wider spectral coverage of THz camera surely expands its applicability