Fused silica fast axis collimator lens for blue high-power laser diodes

Abstract

The divergence of laser diodes is asymmetric and must be collimated in the fast-axis and slow-axis to reach an adequate beam shape for most applications. The most common technical solution is a combination of a Fast Axis Lens (FAC) and a Slow Axis Lens (SAC). These optical components are usually made of glass in combination with an anti-reflective optical coating tuned for a specific wavelength range. During the last decade, high power lasers have become more and more powerful and the requirements for specific collimation optics continuously increased. The FAC beam shaping performance is dependent mostly on the lens design and achieved surface quality, while the thermal behavior of the FAC is dependent on the laser power and the optical absorption within the lens. The solution for a low absorption lens for a high power blue laser diode presented in this paper, is a fused silica FAC. It shows excellent thermal properties and reduces heat generation rate by a factor approximately corresponding to the extinction value ratio when compared to other high refractive glass solutions optimized for blue applications.