Abstract
A simple and handy technique to produce optical fiber components such as Bragg gratings has been used. A CO2 laser beam, focused on a single mode fiber, can change its optical properties locally, allowing therefore the creation of a Bragg grating inside the fiber itself. In the present study we investigate the effect of this laser beam on the fiber and show how optical fiber components can be produced. When exposing a single-mode optical fiber to a high-power CO2 laser beam a small device is developed insdie this fiber. Inside this micro-structure, the optical power is exchanged between the core and the cladding modes. This device may exhibit either a very selective rejection behavior similar to Bragg grating or an oscillating behavior like tapered fiber. The coupled mode theory combined with a mathmatical algorithm can be used to study the propagation of the modes involved in the fiber.