Specialty Optical Fibers Handbook

long-period gratings [15]. Reflectors for fiber lasers [16], wavelength division

filters [16], gain-flattening filters for fiber amplifiers [16], chirped FBGs for pulse

compression and dispersion compensation [16], short- [17–19] or long-period

gratings [20–22] for temperature, strain, and pressure sensors are all examples

showing that photosensitivity revolutionized both the optical fiber communica-

tion and the optical fiber sensor field. Before the advent of photosensitive fibers

and FBGs, these components were made out of bulk optics.

9.2 DESIGN AND FABRICATION

Since the discovery of photosensitivity in optical fibers, many designs driven

by the desire to extend the photosensitive fiber’s limited performances have

been proposed. First, the enhancement ...