Highly Symmetric Optical Fiber Tapers Fabricated With a CO₂ Laser

This letter presents a simple technique that improves the symmetry of tapered fibers fabricated with a continuous-wave CO₂laser. The uniform heat distribution inside an optical fiber is achieved by using a nonscanning dual-spot laser beam which applies heat on two sides of the optical fiber simultaneously. In so doing, highly symmetric tapers are obtained with an ellipticity close to unity. These tapers can be used as low-loss and polarization- dependent loss optical fiber filters or other optical devices such as symmetric fibers lenses.