Low-cost soft-glass diffractive and refractive lenses for efficient mid-IR fiber coupling systems

In this paper we present results of measurements of fiber coupling efficiency for optical mini lenses fabricated from multi-component soft glasses by using low-cost hot embossing technique. We show that soft glasses prove to be a suitable material for fabricating various types of mini lenses to be used in the compact optical system in broadband range from visible up to infrared at around 5 μm. The fabricated elements are biconvex refractive lenses and Fresnel lenses. We discuss soft glass properties, the fabrication process and the results of quality measurements of the fabricated lenses by means of the modulation transfer function. Finally, we report on the use of these diffractive and refractive elements for light coupling to various types of multimode optical fibers from a laser diode.