Integrated Development of CMB-S4 Low-Pass Filters Using a Scalable Proprietary Ablation Process

Metal mesh filters are used to control the transmission of infrared through terahertz radiation in a variety of systems including sensors, cameras, and high-performance telescopes. Currently, high-performance metal mesh infrared filters are fabricated using photolithography but this is a costly and time consuming process and it is limited to filter diameters of 300 mm or less (the largest size that typical lithography systems can produce). In addition, there is currently no domestic manufacturer of these filters. We proposed developing a new manufacturing technique based on a proprietary nano-ablation method that can directly fabricate metal mesh filters without the need to create a photolithography mask, saving time and money, and can be scaled to areas much larger than what lithography tools can easily address. This will be done by modifying and improving a 3D microfabrication technology we have developed that utilizes advanced lasers, optics, and control software. In addition, the team will work on the simulation, design, and testing of the metal mesh filters to create a complete, domestic metal mesh filter capability. The Phase I work will experimentally demonstrate the fundamental science behind the proposed nano- ablation manufacturing technology and provide a feasibility study on scaling the nano-fabrication capability up to filter sizes greater than 600 mm. In additional, metal mesh filters will be designed and simulated using advanced simulation software to provide insight into optimal filter design, materials selection, and an analysis of variations around certain design parameters. Advanced testing will be performed on single-layer test metal mesh filters to characterize their performance. Comparisons will be made between the experimental performance and the simulated performance. If this project is carried over to Phase II, it will create a new, domestic manufacturing capability for metal mesh filters that has the potential to increase the size of the filters by four times the area of currently available filters. In addition, the underlying nano-ablation technology will be able to define micro-scale metallization directly on three-dimensional surfaces and on a variety of substrates. There are many applications for this type of capability, including, for example, very high wiring density flex circuits which can be used as superconducting cables in experimental systems such as quantum computers, millimeter wave telescopes, and other advanced applications.