Efficient fabrication of fused-fiber biconical taper structures by a scanned CO_2 laser beam technique

The driving mechanism of a scanning mirror can cause significant impairment of expanded beam properties, which we investigated for several scanning waveforms. Engineering on the scanning waveform is then carried out by a scanned CO2 laser beam technique to enlarge the uniform heating region for stretching and sintering of silica fibers. Details of the derivation are given. A simple thermal model is presented to account for the relationship between the scanning beam profile and the taper shape. Fusion profiles are also compared for various scanning waveforms. The corresponding scanned beam power distributions are determined experimentally, which enables us to determine precise power density conditions for CO2 laser fusion.