Optical Fiber Sensors by Direct Laser Processing: A Review

Abstract

The consolidation of laser micro/nano processing technologies has led to a continuous increase in the complexity of optical fiber sensors. This new avenue offers novel possibilities for advanced sensing in a wide set of application sectors and, especially in the industrial and medical fields. In this review, the most important transducing structures carried out by laser processing in optical fiber are shown. The work covers different types of fiber Bragg gratings with an emphasis in the direct-write technique and their most interesting inscription configurations. Along with gratings, cladding waveguide structures in optical fibers have reached notable importance in the development of new optical fiber transducers. That is why a detailed study is made of the different laser inscription configurations that can be adopted, as well as their current applications. Microcavities manufactured in optical fibers can be used as both optical transducer and hybrid structure to reach advanced soft-matter optical sensing approaches based on optofluidic concepts. These in-fiber cavities manufactured by femtosecond laser irradiation followed by chemical etching are promising tools for biophotonic devices. Finally, the enhanced Rayleigh backscattering fibers by femtosecond laser dots inscription are also discussed, as a consequence of the new sensing possibilities they enable.

Optical fiber sensors: review of technology and applications

“…All of these evolutions led to the discovery of new applications for different sensors, such as fabry-perot interferometric (FPI) OFSs, FBG sensors, and distributed OFSs. Now at the beginning of the 2000s, there is a promising new optical fiber called "photonic crystal fibers" that contribute to the development of the biophotonics scientific sectors, also to develop and innovate new devices in the industry sector, like wideband optical sources, and new sensors [19]- [24].…”

Recent Advances in Biomedical Photonic Sensors: A Focus on Optical-Fibre-Based Sensing

“…FLICE, also referred to as ultrafast laser-assisted etching (ULAE) or femtosecond laser-assisted etching, has unique capabilities that allow straightforward fabrication of channels (with natural circular cross-sections, not easily achieved with other techniques) with 3D geometries for sensing [11]. Besides typical inscriptions using femtosecond laser processing (see [98]), the combination of fs-laser processing and chemical etching on silica (e.g., HF or KOH) has demonstrated the fabrication of microchannels, X-couplers, filaments, among others [11,99]. Inscribed microchannels could allow liquids to flow in and out of the fibre, expanding the ability to measure diverse parameters.…”

Slit Beam Shaping Technique for Femtosecond Laser Inscription of Symmetric Cladding Waveguides

“…Considering optical fiber manufacturing, there are several ways to inscribe waveguides, as indicated in the review by Pallarés-Aldeiturriaga et al [17]. There is a first case in which the cylindrical aberrations of the fiber are not corrected, giving rise to what is known as filamented waveguides [18].…”