Numerical aperture of the UHNA3 fiber modified in CO2 laser beam

The dataset shows results of measured numerical apertures (NAs) for UHNA3 fiber modified in the CO2 laser beam with Fujikura LZM100 splicer, in the following techniques: tapering (as function of taper length and diameter), creating ball lens (for different radii of the ball), thermal expansion of core (TEC) (as function of maximum laser power used for fiber heating). For tapering and ball lenses standard procedures and programs available in the software for Fujikura LZM100 splicer were used. For TEC, the fiber was placed across the laser beam and the power of the laser was increased linearly up to a chosen maximum value over time of approximately one minute. Then, the laser was kept at the maximum power for additional one minute. As the final step, the fiber was cleaved in the center of the heated section. The NAs were determined by measurement of beam divergence angle in the far field at the output of the modified end at 1050 nm illumination.