Ultrafast z-scanning for high efficiency laser material processing (Conference Presentation)

Abstract

The mass production of micro-elements in scientific research and industry, such as micro-electronic devices, bio-compatible micro-devices and micro-optical elements, has necessitated the development of high-efficiency laser processing techniques. High-throughput laser material processing demands precise control of the laser beam position to achieve optimal efficiency, but existing methods can be both time-consuming and cost-prohibitive. In the paper, we demonstrate a new high-throughput material processing technique based on rapidly scanning the laser focal point along the optical axis using an acoustically-driven variable focal length lens. Our results show that this scanning method enables higher processing rates over a range of defocus distances in various materials including metals, semiconductors, polymers and glass. In a specific example of silicon, we achieve a nearly threefold increase in the machining rate while maintaining sharp side walls and a small spot size. This method holds great potential for improving material processing efficiency in traditional systems, and also opens the door to applying laser processing to pieces with uneven topography that have traditionally been difficult to process.