Due to the recent rapid industrialization and urbanization across the world, chemicals are released into the environment at an unprecedented rate. Gas sensors, in particular, interferometric based devices represent an important toolkit for air quality monitoring. Amongst different interferometers, linear variable filter (LVF) holds the promise of a fixed optical component that can be operated under various conditions. In this work, oxide pillars were deposited on a [Si-SiO2] mirror coated wafers. Thick oxide deposition was performed using a low temperature high density chemical vapor process with photoresist as mask to form pillars. By sandwiching two such substrates together, a milli-degree taper angle was formed by a difference in pillar height. The mated normal incidence LVF was demonstrated with an operating range of $0.7~\mu \text{m}$ , full width half maximum of 230 nm at 3,500 nm and was tested for the presence of acetone vapor. The relationship between transmission intensity and acetone concentration was plotted with a correlation R2 of 0.972.

中文翻译：

---

用于丙酮水平监测的中红外区域中高度紧凑的线性可变滤波器

由于最近世界范围内的快速工业化和城市化，化学品以前所未有的速度释放到环境中。气体传感器，特别是基于干涉测量的设备，是空气质量监测的重要工具包。在不同的干涉仪中，线性可变滤波器 (LVF) 具有固定光学组件的潜力，可以在各种条件下运行。在这项工作中，氧化物柱被沉积在 [Si-SiO2] 镜面涂层晶片上。使用低温高密度化学气相工艺以光刻胶为掩模进行厚氧化物沉积以形成柱。通过将两个这样的基板夹在一起，柱高度的差异形成了毫度的锥角。交配的正常发生率 LVF 的操作范围为 $0.7~\mu\text{m}$ ，在 3,500 nm 处的半峰全宽为 230 nm，并测试了丙酮蒸汽的存在。透射强度和丙酮浓度之间的关系绘制成相关性 R2 为 0.972。