Specialty Optical Fibers Handbook

16.4.5 Partial and Full Core Removal

In principle, the wave-guiding field can be further manipulated if the fiber

core is fully, or partially, removed, and the empty core is refilled with certain

functional material that replaces the removed core and rebuilds the waveguide

characteristics. The method and technique for partially and fully removing the

core of the D-shape fiber have been proposed [39]. This technique enables new

and exciting opportunities in the field of in-fiber electro-optic devices by refilling

the removed core with an electro-optic active polymer to fabricate, for example,

all-fiber modulators. The selective removal of the core is based on the differential

etching of HF acid to the fiber materials. The pure HF acid etches the germa- ...