Specialty Optical Fibers Handbook

The method can control the etching depth very accurately with excellent

repeatability. The accuracy of etching also depends on the length of the etched

section. Estimated accuracy for etching D-shape fiber of 3-cm long is several tens

of nanometers.

The polarimetric monitor provides a sensitive measurement on the relative

etching degree so long as the cladding-water interface reaches the evanescent

field tail. As described later, the degree of etching required to manufacture fiber

polarizers and couplers is slight, as only the tail of the evanescent field is barely

exposed. On the other hand, to achieve a better manipulation of the guided light,

a deeper ...