Beam Quality and Fiber Coupling in Lasers

This lecture covers the concept of beam quality in lasers, focusing on the beam parameter product (BPP) and its significance in applications such as fiber coupling. The instructor begins by reviewing the definition of beam quality and the importance of the M² parameter, which quantifies how closely a laser beam resembles an ideal Gaussian beam. The discussion includes practical applications of beam quality in various fields, such as welding and printing, emphasizing the relationship between beam quality and laser power. The instructor explains how to measure M² through experimental setups and the implications of beam quality on laser performance. Additionally, the lecture introduces relaxation oscillations, detailing how quickly a laser can be modulated and the factors influencing this speed. The instructor provides insights into the design considerations for coupling laser light into fibers, highlighting the need to maintain the beam parameter product for optimal performance. Overall, the lecture integrates theoretical concepts with practical engineering challenges in laser applications.