GOALI: Nano-Machining of Diamond Mirror for High-Power Laser Optics

Harvard University, Cambridge MA

Investigators

Abstract

While breakthroughs in microfabrication have already allowed for billions of transistors to be integrated on a single integrated circuit, demands for even more computational power require denser chips and smaller transistors. Extreme ultraviolet lithography has emerged as a leading technique that can enable this. However, its performance is limited by the amount of ultraviolet light that can be produced. Optical mirrors used in these systems cannot withstand extremely high optical intensities and often fail, thus limiting the reliability of the system and increasing the production cost. This Grant Opportunity for Academic Liaison with Industry (GOALI) award addresses the need for better mirrors and develops a novel nanomanufacturing technique that allows for optical components to be fabricated in diamond. This is challenging since diamond is one of the hardest materials to shape. The team leverages expertise in material science, nano-machining, optics, and laser physics to overcome these challenges and develop a novel and scalable nanomanufacturing technique. This project has the potential to transform the way chips are made, which has great economic and societal impact owing to the ubiquitous presence of micro-chips in everyday life. In addition to the semiconductor industry, nano-machined diamond components have broad and direct impact on many technologies that use high power lasers, including defense, medicine, and automotive industry. The team's findings are shared with the general public through continued collaborations with Museum of Science (Boston), giving public lectures, and participating in science fairs. In extreme ultraviolet source a high-power carbon-dioxide laser is focused onto micron-scale tin droplets, thus vaporizing them and resulting in plasma that gives off extreme ultraviolet light. Despite many decades of work, the overall conversion efficiency (infrared to ultraviolet) is only a few percent. As a result, kilowatts of infrared power are required, which demands better mirrors, since currently used ones often fail at high optical intensities. This project develops a novel nano-machining technique for forming three-dimensional nanostructures on the surface of bulk diamond surfaces, that feature > 99% reflectivity. Such diamond mirrors can handle much larger optical intensities and have much longer lifetime than state-of-the-art mirrors. In addition, the team develops a wide range of high-power diamond-based optical components, including filters, polarizers, wave-plates, and beam combiners. This collaborative effort focuses on fundamental understanding of nano-machining of optical surfaces from bulk materials and industry-university relationship through interactive research and exchange of students and engineers. The industrial partner helps provide the necessary equipment, metrology and laser expertise to advance this research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.