Elaboration and optimization of microlens for high optical coupling efficiency

Dip coating technique has the potential to provide a simpler and more cost-effective means of forming an optical fiber microcollimator composed of parabolic Polymethyl methacrylate microlenses for various applications. The effects of dip-coating operating parameters such as withdrawal speed on the thickness of a microlens were investigated in this work. Zemax (R) software was used to validate the analytical results and to assess the efficiency of the optical coupling. The obtained waist and working distance values, make possible the optimization of the optical coupling between a microcollimator and a laser beam, as well as between a microcollimator and an optical fiber. The simulation results of the coupling between the microcollimator and the laser beam show that the optical coupling efficiency eta is about 99% with an optimal microlens radius R = 19.14 mu m, a waist size W-1 = 2.49 mu m and a working distance Z(w )= 41.78 mu m. However, the optimal microlens for the coupling between the microcollimator and the optical fiber has a minimum curvature radius about 28.78 mu m. We believe that these results are of a big interest in many applications in optical experiments and laser-optical fibers applications.