Porous silicon Fabry-Pérot (PS-FP) filters operating in the long wavelength infrared (LWIR) range are demonstrated and studied. Porous silicon (PS) offers many advantages for such filters, including improved optical and mechanical properties compared to other LWIR filter materials, and the ability to modulate porosity to form multilayer structures that are compatible with conventional semiconductor technologies. This work discusses the optical and the mechanical characterizations of what are the first MEMS-based suspended PS-FP filters operating in the LWIR range. Methods developed to model and characterize PS-FP filters are discussed, with characterization a challenge for such porous structures considering their low refractive index and low Young’s modulus. The transmittance measurements show that introducing notches at the four corners of the top mirror minimizes the bowing of the top mirror significantly. The stress measurements of attached films show that the lattice mismatch at the PS/silicon interface is likely the key factor controlling the stress in multilayer PS thin films. The micromachining techniques developed to form a resonance cavity within PS-FP filters can also be tuned to reduce the stress mismatch and the absorption loss in the LWIR range. This study shows exciting promise for the use of micromachined PS-based filters for LWIR operation.

演示和研究了在长波长红外 (LWIR) 范围内工作的多孔硅法布里-珀罗 (PS-FP) 滤波器。多孔硅 (PS) 为此类滤波器提供了许多优势，包括与其他 LWIR 滤波器材料相比改进的光学和机械性能，以及调节孔隙率以形成与传统半导体技术兼容的多层结构的能力。这项工作讨论了在 LWIR 范围内运行的第一个基于 MEMS 的悬挂式 PS-FP 滤波器的光学和机械特性。讨论了为建模和表征 PS-FP 滤波器而开发的方法，考虑到它们的低折射率和低杨氏模量，表征这种多孔结构是一个挑战。透射率测量表明，在顶部反射镜的四个角处引入凹口可显着减少顶部反射镜的弯曲。附着膜的应力测量表明，PS/硅界面处的晶格失配可能是控制多层 PS 薄膜应力的关键因素。为在 PS-FP 滤波器内形成谐振腔而开发的微加工技术也可以进行调整，以减少 LWIR 范围内的应力失配和吸收损耗。这项研究显示了使用基于微加工 PS 的滤波器进行 LWIR 操作的令人兴奋的前景。为在 PS-FP 滤波器内形成谐振腔而开发的微加工技术也可以进行调整，以减少 LWIR 范围内的应力失配和吸收损耗。这项研究显示了使用基于微加工 PS 的滤波器进行 LWIR 操作的令人兴奋的前景。为在 PS-FP 滤波器内形成谐振腔而开发的微加工技术也可以进行调整，以减少 LWIR 范围内的应力失配和吸收损耗。这项研究显示了使用基于微加工 PS 的滤波器进行 LWIR 操作的令人兴奋的前景。