It is a technique that uses controlled heat to permanently fuse two optical fiber ends together. Unlike mechanical splicing, which relies on alignment sleeves and index-matching gel, this thermal approach creates a continuous glass path between fibers. There commonly is a limit of 1mm for the maximum diameter of fused components, so micro-optical lenses or gradient index (GRIN) lenses cannot be. Regardless of your level of experience, creating high-quality, high-performance fiber optic networks requires developing your skills in fusion splicing. Initially, the ends of the fibers are placed very close to each other, leaving only a tiny gap.