Fabrication of polymer microlenses on single mode optical fibers for light coupling

• A technique for manufacturing fiber optic micro-collimators is presented.
• Micro-cavities chemically etched at the end of fibers are used.
• The injection of PDMS into the micro-cavities produces the formation of microlenses.
• A theoretical study has enabled the optimization of the radius of curvature of the microlenses.
• The experimental results reveal a maximum coupling for the optimal radius.

In this paper, we present a technique for producing fibers optics micro-collimators composed of polydimethylsiloxane PDMS microlenses of different radii of curvature. The waist and working distance values obtained enable the optimization of optical coupling between optical fibers, fibers and optical sources, and fibers and detectors. The principal is based on the injection of polydimethylsiloxane (PDMS) into a conical micro-cavity chemically etched at the end of optical fibers. A spherical microlens is then formed that is self-centered with respect to the axis of the fiber. Typically, an optimal radius of curvature of 10.08 μm is obtained. This optimized micro-collimator is characterized by a working distance of 19.27 μm and a waist equal to 2.28 μm for an SMF 9/125 μm fiber. The simulation and experimental results reveal an optical coupling efficiency that can reach a value of 99.75%.