Fiber-optic bolometers (FOBs) intended for plasma radiation measurement in magnetically confined fusion have been previously developed using a silicon pillar that functions as both a Fabry–Perot interferometer (FPI) for temperature measurement and an absorber for the radiation. We report an FOB design that can significantly improve the detection sensitivity over earlier designs by engineering the absorber of the FOB. Our design uses the fact that, compared with a silicon pillar, a gold film with the same x-ray absorption thickness will show a much higher temperature rise from a given power density of the radiation. Therefore, the responsivity of an FOB can be improved by attaching a large gold disk to the silicon FPI as the absorber. We have developed a fabrication method for FOBs of such design and obtained an FOB with a 4-µm-thick, 0.6-mm-diameter gold disk attached to a 200-µm-diameter, 100-µm-thick silicon FPI. We have characterized the noise, responsivity, response time, and noise-equivalent power density (NEPD) and compared these with the earlier design where the absorber is mainly the silicon FPI itself. The experimental result suggests that the FOB with the gold disk achieves a responsivity of ∼2.8 mK/(W/m²) and a noise-equivalent-power-density of 0.13 W/m², which are, respectively, more than nine times larger and six times smaller compared to the FOB using a previous design. Improved NEPD and good absorption over a broad frequency range will make the FOB more attractive for applications in magnetic-confinement fusion devices.

中文翻译：

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光纤硅法布里-珀罗干涉测辐射热仪，具有改进的磁限聚变检测极限

先前已经开发出了用于磁约束聚变中的等离子体辐射测量的光纤辐射热测量仪（FOB），该硅辐射管既用作温度测量的Fabry-Perot干涉仪（FPI），又用作辐射吸收器。我们报告了一种FOB设计，通过设计FOB的吸收器，该设计可以比早期设计大大提高检测灵敏度。我们的设计利用这样一个事实，即与硅柱相比，具有相同x射线吸收厚度的金膜在给定的辐射功率密度下将显示出更高的温度升高。因此，通过将大的金盘附着到作为吸收体的硅FPI上，可以提高FOB的响应性。我们已经开发出了这种设计的FOB的制造方法，并获得了带有4个FOB的FOB。微米厚度，直径0.6毫米的金盘连接到直径200微米，厚度100微米的硅FPI。我们已经对噪声，响应度，响应时间和等效噪声功率密度（NEPD）进行了表征，并将这些与早期设计（吸收体主要是硅FPI本身）进行了比较。实验结果表明，带有金盘的FOB达到约2.8 mK /（W / m ²）的响应度和0.13 W / m ²的噪声当量功率密度，分别是其九倍以上与使用先前设计的FOB相比，体积更大，体积更小六倍。改进的NEPD和在宽频率范围内的良好吸收性能将使FOB在磁约束融合设备中的应用更具吸引力。