Review of femtosecond laser direct writing fiber-optic structures based on refractive index modification and their applications

Zhao, Jian; Zhao, Yong; Peng, Yun; Lv, Ri-qing; Zhao, Qiang

doi:10.1016/j.optlastec.2021.107473

Cited by 34 publications

(13 citation statements)

References 195 publications

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“…However, driven by the demands for novel FBGs able to operate in high temperature environments (400 °C to 1800 °C) or used as vector bending sensors, femtosecond lasers are widely becoming extremely useful because of ultra-short pulse width and extreme-high peak power, which can induce fiber core refractive index change in diverse transparent materials, such as silica, single crystal, glasses, etc., [ 3 ]. Compared to phase mask technology and holographic interferometry, direct writing technologies, such as point-by-point (PbP) and line-by-line (LbL) for FBG inscriptions, demonstrate unique advantages of high accuracy with reduced thermal effect, since refractive indices could be modified to the size of sub-microns inside transparent materials by focusing a femtosecond laser beam by a high NA objective with high magnification [ 4 , 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Direct Bragg Grating Inscription in Single Mode Step-Index TOPAS/ZEONEX Polymer Optical Fiber Using 520 nm Femtosecond Pulses

Chen

Gao

et al. 2022

Polymers

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We experimentally report fiber Bragg gratings (FBGs) in a single mode step-index polymer optical fiber (POF) with a core made of TOPAS and cladding made of ZEONEX using 520 nm femtosecond pulses and a point-by-point (PbP) inscription method. With different pulse energies between 69.8 nJ and 80.4 nJ, 12 FBGs are distributed along the cores of two pieces of POFs with negative averaged effective index change up to ~6 × 10−4 in the TOPAS. For POF 1 with FBGs 1–6, the highest reflectivity 45.1% is obtained with a pulse energy of 76.1 nJ. After inscription, good grating stability is reported. Thanks to the post-annealing at 125 °C for 24 h, after cooling the grating reflectivity increases by ~10%. For POF 2 with FBGs 7–12, similar FBG data are obtained showing good reproducibility. Then, the FBGs are annealed at 125 °C for 78 h, and the average reflectivity of the FBGs during the annealing process increases by ~50% compared to that before the annealing, which could be potentially applied to humidity insensitive high temperature measurement.

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Section: Introductionmentioning

confidence: 99%

Direct Bragg Grating Inscription in Single Mode Step-Index TOPAS/ZEONEX Polymer Optical Fiber Using 520 nm Femtosecond Pulses

Chen

Gao

et al. 2022

Polymers

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“…This is achieved by generating a periodic change in the fiber core refractive index, which produces a dielectric mirror unique to the wavelength [18]. Generally, fiber Bragg gratings are created using an extreme ultraviolet (UV) source such as a UV laser by systematical variation of the refractive index at the center of a special type of optical fiber [19]. Fresnel reflection is the fundamental principle behind the operation of an FBG, where light moving through media with different refractive indices at the interface will reflect and refract.…”

Section: Experimental Investigationmentioning

confidence: 99%

Delphi Collaboration Strategy for Multiagent Optical Fiber Intelligent Health Monitoring System

et al. 2022

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Optical fiber sensors are very attractive in mechanical structure intelligent health monitoring system due to some unique characteristics, such as immunity to electromagnetic interference and to aggressive environments, high sensitive and fast response, small physical dimension, excellent resolution and range, and so on. For improving the accuracy and reliability of the optical fiber intelligent health monitoring system in practical engineering application, the collaboration and decision-making strategy based on Delphi method for multiagent optical fiber intelligent health monitoring system is studied in this paper. The proposed system is mainly composed of optical fiber sensing agent, intelligent evaluation agent, and system collaborative decision-making agent. The intelligent evaluation agent is used to evaluate the health status of the monitored mechanical structures. Delphi method is used by the system collaborative decision-making agent to consult each intelligent evaluation agent. Meanwhile, the collaborative partner selection algorithm is used to select the intelligent evaluation agent participating in the collaboration, and the intelligent evaluation agent that does not participate in the decision-making is dynamically modified by the decision result. The experiment for an aircraft wing box as the typical engineering structure is carried out and the verification system is designed, the decision result is compared with that without dynamic correction of the evaluation result. The comparative results indicate that the evaluation accuracy and reliability of the monitored mechanical structural damage are improved significantly after multiple rounds of collaboration and decision making.

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“…In addition to the above, these fiber-optic microstructures also have interesting applications in areas such as fiber-optic lasers [8], fiber Bragg gratings (FBGs) [9], long period fiber gratings (LPGs) [10], tilted fiber Bragg gratings [11], interferometers [12--14], couplers [15] or birefringence adjustable elements [1], [16]. In further, changes in the birefringence of a fiber can be caused by its twist [17].…”

Section: Introductionmentioning

confidence: 99%

Wavelength-switchable L-band fiber laser assisted by random reflectors

Pérez-Herrera

Roldán-Varona

Sanchez-Gonzalez

et al. 2023

J. Eur. Opt. Society-Rapid Publ.

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A wavelength-switchable L-band erbium-doped fiber laser (EDFL) assisted by an artificially controlled backscattering (ACB) fiber reflector is here presented. This random reflector was inscribed by femtosecond (fs) laser direct writing on the axial axis of a multimode fiber with 50 µm core and 125 µm cladding with a length of 17 mm. This microstructure was placed inside a surgical syringe to be positioned in the center of a high-precision rotation mount to accurately control its angle of rotation. Only by rotating this mount, three different output spectra were obtained: a single wavelength lasing centered at 1574.75 nm, a dual wavelength lasing centered at 1574.75 nm and 1575.75 nm, and a single wavelength lasing centered at 1575.5 nm. All of them showed an optical signal-to-noise ratio (OSNR) of around 60 dB when pumped at 300 mW.

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Review of femtosecond laser direct writing fiber-optic structures based on refractive index modification and their applications

Cited by 34 publications

References 195 publications

Direct Bragg Grating Inscription in Single Mode Step-Index TOPAS/ZEONEX Polymer Optical Fiber Using 520 nm Femtosecond Pulses

Direct Bragg Grating Inscription in Single Mode Step-Index TOPAS/ZEONEX Polymer Optical Fiber Using 520 nm Femtosecond Pulses

Delphi Collaboration Strategy for Multiagent Optical Fiber Intelligent Health Monitoring System

Wavelength-switchable L-band fiber laser assisted by random reflectors

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