Astronomical instruments with hundreds of optical fibers are increasingly common in the setup of the modern telescopes. Multi-fibers connectors assure precise connection among several optical fibers, providing flexibility for instrument exchanges. In fact, highly multiplexed instruments require a fiber connector system that can deliver excellent optical performance and reliability. In this paper, we present a multi-fiber connector developed to assure strong and accurate connection. MULEC is a multi-fibers connector where each fiber end, suitably polished, is coupled at a microlens such that the beam of light from one end of the optical fiber can be collimated and then, focused by another microlens coupled with another optical fiber end. Given the optical magnification inferred by the microlens, the optical accuracy of the coupling is significantly increased.

MULEC is easy to coupling using powerful micro magnets and also, has devices for adjustment in x, y, z and rotation. The optical fiber arrangements on both sides of the connector are constructed with a special dark composite, made with refractory oxide, which is able to sustain its polishing with minimum quantities of abrasives during the polishing process. In other words, when in polishing, the detachment of the refractory oxide nanoparticles reinforces gently the polishing process and increases the efficiency of this procedure.

The bench tests with these connector systems will be implemented in a near future and the chosen fibers should measure the throughput of light and the stability after many connections and disconnections. In this paper, we describe some optical features and mechanical details.