Analysis is made of the characteristics of a special optical fiber widely used in Light Triggered Thyristors（LTT） and systematical study of such crucial optical characteristics as the dopants of the fiber core and cladding and the cladding-core diameter ratio

providing some reference for choosing specialty optical fibers with preferable cost performance for LTTs.The results indicate that optical fibers with core diameter of 200 μm and cladding diameter of 250 μm designed in step index profile

Ge-F codoped in the core with Ge concentration of 16 mol% and F of 5 mol%

and cladding doped with F with concentration of 1 mol% have better triggering performance and fit for LTT applications.