Micromachining of optical fibers using the selective etching of doped silica glass

This paper presents a highly effective micromachining process that can reform a section of an optical fiber into an all-fiber, complex photonic microstructure. The proposed process utilizes specially designed structure forming fibers that are reformed into various complex shapes through selective etching. The control over the etching rate of the structure-forming fiber sections is achieved by the introduction of dopants, particularly phosphorus pentoxide, into silica glass through the standard fiber manufacturing technology. Doping with appropriate dopants and dopant concentrations can be used to create highly-preferential etchable areas within a fiber cross-section that can be selectively removed upon exposing the fiber to the etching medium. The doped areas in the fiber cross-section can thus serve as sacrificial layers, similar to those in the case of silicon MEMS production. Thus, the shaping of fiber devices can be achieved through the design and fabrication of structure-forming fibers.