Two-step process for micro-lens-fibre fabrication using a continuous CO2 laser source

Hemispherical micro-lenses have been fabricated using a single-mode optical fibre end. The process consists of a new two-step fabrication using only a continuous CO2 laser source. In the first step, the fibre is heated with the laser and stretched until it splits, resulting in two symmetrical tapers. In the second step, the micro-lens is formed by melting the rotating fibre tip. Parameters of heating and stretching are optimized to ensure reproducibility. Characterizations have been performed and confirm the assumed Gaussian beam profile. We performed the focal length and beam waist measurements and compared them with theoretical approximations. We showed the flexibility of the fabrication process and the interest of micro-lenses in several applications.