A review of focused ion beam applications in optical fibers.

Focused ion beam (FIB) technology has become a promising technique in micro- and nano-prototyping due to several advantages over its counterparts such as direct (maskless) processing, sub-10 nm feature size, and high reproducibility. Moreover, FIB machining can be effectively implemented on both conventional planar substrates and unconventional curved surfaces such as optical fibers, which are popular as an effective medium for telecommunications. Optical fibers have also been widely used as intrinsically light-coupled substrates to create a wide variety of compact fiber-optic devices by FIB milling diverse micro- and nanostructures onto the fiber surface (endfacet or outer cladding). In this paper, the broad applications of the FIB technology in optical fibers are reviewed. After an introduction to the technology, incorporating the FIB system and its basic operating modes, a brief overview of the lab-on-fiber technology is presented. Furthermore, the typical and most recent applications of the FIB machining in optical fibers for various applications are summarized. Finally, the reviewed work is concluded by suggesting the possible future directions for improving the micro- and nanomachining capabilities of the FIB technology in optical fibers.