Fabrication of a bi-directional firing multimode fiber using a high repetition rate femtosecond laser and a CO2laser

Light emission from the distal end of an optical fiber is governed by the structure of the fiber tip and the additional optical component at the fiber tip. We describe the microstructuring of the distal end of an optical fiber using a high repetition rate femtosecond laser and a continuous wave CO 2 laser. The tip of a multimode fiber with a core/clad diameter of 400/440 μm was micromachined into a cone structure using a femtosecond laser. The machined tip was re-exposed to a CO 2 laser, and the surface of the cone structure underwent melting and re-solidification. This resulted in the smoothing of the surface of the cone and subsequent specular reflection at its surface. We were able to demonstrate bi-directional (axial and radial) emission of the light from the developed fiber tip.