Metallurgy

Materials science

Optical fiber

Fiber optic sensor

Wavelength

Photonic-crystal fiber

Laser

Physics

Cladding (metalworking)

Optics

Long-period fiber grating

Plastic optical fiber

PHOSFOS

Femtosecond

Fiber laser

Optoelectronics

Fiber Bragg grating

Sensors

A review of recent progress in the use of infrared femtosecond lasers to fabricate optical fiber sensors that incorporate fiber Bragg gratings (FBG) and random fiber gratings (RFG) is presented. The important advancements in femtosecond laser writing based on the phase mask technique now allow through-the-coating (TTC) fabrication of Bragg gratings in ultra-thin fiber filaments, tilted fiber Bragg gratings, and 1000 °C-resistant fiber Bragg gratings with very strong cladding modes. As an example, through-the-coating femtosecond laser writing is used to manufacture distributed fiber Bragg grating sensor arrays for oil pipeline leak detection. The plane-by-plane femtosecond laser writing technique used for the inscription of random fiber gratings is also reviewed and novel applications of the resultant devices in distributed temperature sensing, fiber lasers and fiber laser sensors are discussed.

Ultrafast Laser Processing of Optical Fibers for Sensing Applications