Optical fiber tapers produced by near-infrared laser radiation

Abstract

The use of CO2 lasers in the production of optical fiber sensors is a well proven application, especially in writing long period fiber gratings. The mid-infrared radiation (MIR) emitted by these lasers is highly absorbed by the glass optical fibers commonly used as fiber-based sensors, and the consequent heating easily leads to melting. Making use of this advantage, the application of this radiation in the tapering of optical fibers is demonstrated. A continuous wave emission CO2 laser is used in short duration pulses, a cylindrical lens focuses the beam on the fiber and a small weight produces the effect of pulling the fiber. The resulting tapers’ characteristics (length, degree of symmetry and central diameter, or waist) are analyzed as well as the influence of the operational parameters involved in the process (laser power, pulse duration and number of pulses). The potential of this technique is demonstrated with special attention to its use in the development of optical fiber-based sensors.