Hemi-ellipsoidal microlensed fiber based on polishing and polymer technology

This paper represents a development of a new advanced technology to fabricate and characterize micro-collimators with hemi-ellipsoidal microlenses at single-mode fibers outputs. The proposed method utilizes the controlled mechanical micromachining technique based on the variation of the speed of the fiber around its axis in both X and Y directions followed by the injection of a quantity of polydimethylsiloxane (PDMS) to form the hemi-ellipsoidal microlenses. The experimental results show that this technique allows to obtain a wide variety of ellipticity diameters ratios from 0.68 to 0.84. An elliptical ratio of radii of curvature Ry/Rx in a range of 0.51 at 0.86 is also obtained. In this investigation a mode field diameters MFD in an interval between 3.26 mu m and 9.93 mu m have been realized. The measurement results demonstrate that the proposed technology allows to fabricate hemi-ellipsoidal microlenses having an MFD ellipticity ratios of about 0.60 to 0.97 in near field promising for micro-collimator suitable to match an elliptical laser beam to the circular one of a fiber.