SBIR-STTR Award

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.

Problem Statement: Terahertz radiation is emerging as a valuable portion of the electromagnetic spectrum for imaging with important applications in medicine, security, defense, manufacturing, scientific research, and is a leading technology for “6G” wireless networking. The traditional multi-step lithography-based approach for manufacturing THz filters is expensive and limited to diameters of 30 cm. However, lower cost, high quality THz filters of arbitrary size are required for many applications, including the CMB-S4 program. How this Problem Will Be Addressed: The proposed technology is a rapid, low-cost fabrication method for multi-layer, metal-mesh THz filters that will produce these filters using a direct-write approach at a lower cost, in higher volumes, and with arbitrarily large diameters. What was Done in Phase I: The Phase I project experimentally demonstrated that this new fabrication technology has the ability to create the microstructures necessary for these filters and demonstrated a single-layer THz filter during the project. The fabrication technology can also create other structures, similar to the microstructures in THz filters, that are desired by potential industrial customers. What is Planned for the Phase II Project: The Phase II project will develop a complete large-area, nano-laser-ablation tool for filters along with supporting capabilities of filter design and testing to provide custom fabricated multi-level metal mesh filters for a variety of THz applications. Commercial Applications and Other Benefits If Carried Over to Phase II: Commercial applications for the proposed high-performance filters include THz imaging, spectroscopy, and wireless communications. These applications would benefit industries such as medicine, homeland security and defense, consumer devices, food safety, non-destructive evaluation for manufacturing, and scientific research. The nano-ablation capability will also be broadly useful as a rapid microfabrication tool that would be useful in microsystems, optics, integrated circuits, and circuit board production.