Multiple Cladding Fiber Bragg Gratings Inscribed By Femtosecond Laser Point-by-Point Technology

Femtosecond laser point-by-point (PbP) technology can be used as a direct writing method to inscribe fiber Bragg gratings (FBGs) into the cladding of optical fibers. When the refractive index modulated area of cladding FBGs (CLFBGs) is close to the core-cladding interface, the CLFBGs exhibit characteristics similar to conventional core-based FBGs. When bending was applied, the reflected power of the CLFBGs changed significantly and showed an orientation dependence on the fiber bending direction. The CLFBG inscription method provides a new opportunity to fabricate vector sensing devices, which can be realized by parallelly inscribed multiple CLFBGs. Compact CLFBGS with a low insertion loss (less than 0.05 dB) have application value in the fields of optical fiber sensors, communications, and lasers.

Automated summary

Femtosecond laser point-by-point technology allows direct writing of FBGs into the cladding of optical fibers, creating CLFBGs with characteristics similar to conventional core-based FBGs. These compact CLFBGs, with low insertion loss, have application value in the fields of optical fiber sensors, communications, and lasers, particularly for manufacturing vector sensing devices.