Fabrication of asperical lensed optical fibers with an electro-static pulling of SU-8 photoresist.

A novel method is presented for fabricating lensed optical fibers for enhancing the coupling efficiency between high-power IR laser diodes and gradient-index fibers (GIF). SU-8 photoresist is attached to the fiber tip by means of surface tension forces and a cone-shaped micro-lens structure is then formed using an electrostatic pulling method. It is shown that micro-lenses with various radii of curvature can be easily formed by tuning the intensity of the electric field used in the pulling process. Experimental results show that for a laser diode chip with a central wavelength of 1310 nm, a coupling efficiency of 78% can be obtained using a lensed optical fiber with a radius of curvature of 48 μm. By contrast, the coupling efficiency of a traditional flat-end fiber is just 40%. Overall, the fabrication method proposed in this study provides a rapid and low-cost solution for the mass production of high-quality lensed optical fibers.

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