Characterization of refractive index change and fabrication of long period gratings in pure silica fiber by femtosecond laser radiation

Ahmed, Farid; Joe, Hang-Eun; Min, Byung Kwon; Jun, Martin B. G.

doi:10.1016/j.optlastec.2015.05.018

Cited by 24 publications

(14 citation statements)

References 31 publications

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“…The exponential curve in Figure 9 can be used to calibrate the nonlinearity between the transmission loss and the electrical current variation for the OFCS. In addition, the behavior of the transmission loss agrees well [23], and is based on the periodic refractive index modulation caused by the external deformation. When the LPFG is placed under deformation, it generates a periodic strain field owing to the expanded cross section area, and thus affects the refractive index periodic distribution of the optical fiber and produces an attenuated loss dip in the spectrum, as shown in Figure 6.…”

Section: Resultsmentioning

confidence: 60%

“…Several techniques have been reported concerning the fabrication process of the gratings, such as exposure to ultraviolet (UV) irradiation [22], irradiation by femtosecond pulses in the infrared (IR) [23], irradiation by CO 2 lasers [24], as well as ion beam implantation, etching, mechanical arrangements, and electric arc discharges [25,26,27,28]. Besides, the LPFG usually has a period (Λ) of 100 µm to 1000 µm and the grating promotes coupling between the propagating core mode (LP 01 ) and the m different co-propagating cladding modes (LP 0m ).…”

Section: Theorymentioning

confidence: 99%

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An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

Delgado

Carvalho

Coelho

et al. 2016

Sensors

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In this paper, we propose and experimentally investigate an optical sensor based on a novel combination of a long-period fiber grating (LPFG) with a permanent magnet to measure electrical current in unmanned aerial vehicles (UAVs). The proposed device uses a neodymium magnet attached to the grating structure, which suffers from an electromagnetic force produced when the current flows in the wire of the UAV engine. Therefore, it causes deformation on the sensor and thus, different shifts occur in the resonant bands of the transmission spectrum of the LPFG. Finally, the results show that it is possible to monitor electrical current throughout the entire operating range of the UAV engine from 0 A to 10 A in an effective and practical way with good linearity, reliability and response time, which are desirable characteristics in electrical current sensing.

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Section: Resultsmentioning

confidence: 60%

Section: Theorymentioning

confidence: 99%

An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

Delgado

Carvalho

Coelho

et al. 2016

Sensors

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show abstract

“…Coelho et al [41] calculated a refractive index change in the order of 2 × 10 −4 and 3 × 10 −4 for the core and cladding, respectively when writing an LPG in a single mode fibre using mid-infrared laser radiation. The same order of magnitude of refractive index change (4.49 × 10 −4 ) is also needed for femtosecond laser radiation [42].…”

Section: Fabricationmentioning

confidence: 99%

Optical Fibre Long-Period Grating Sensors Operating at and around the Phase Matching Turning Point

Wong¹,

Juan²,

Ibsen³

et al. 2019

Applications of Optical Fibers for Sensing

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Optical fibres have been exploited as sensors for many years and they provide a versatile platform with a small form factor. Long-period gratings (LPGs) operating at and around the phase matching turning point (PMTP) possess some of the highest sensitivities to external perturbations in the family of LPG-based sensor devices. This type of optical fibre grating has been demonstrated as a sensor for use in a wide range of applications. In this review chapter, an overview of PMTP LPGs is presented and the key developments, findings and applications are highlighted. The fabrication considerations and sensor limitations are also discussed.

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“…Due to the coupling of fiber optic core modes into the cladding mode, the transmission valley appears. The phase matching between forward-propagating core mode and cladding mode in an LPFG is governed by [6,18]:

λ_{r e s} = [n_{e f f}^{c o r e} (λ_{r e s}) - n_{e f f}^{c l (m)} (λ_{r e s})] normal∆

where λ res is the resonant wavelength,

n_{e f f}^{c o r e}

is the effective index of the core mode, and

n_{e f f}^{c l (m)}

is the effective index of the mth-order cladding mode.…”

Section: Experimental Validation Of the Modeled Refractive Index Lmentioning

confidence: 99%

Numerical Approach to Modeling and Characterization of Refractive Index Changes for a Long-Period Fiber Grating Fabricated by Femtosecond Laser

et al. 2016

Self Cite

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A 3D finite element model constructed to predict the intensity-dependent refractive index profile induced by femtosecond laser radiation is presented. A fiber core irradiated by a pulsed laser is modeled as a cylinder subject to predefined boundary conditions using COMSOL5.2 Multiphysics commercial package. The numerically obtained refractive index change is used to numerically design and experimentally fabricate long-period fiber grating (LPFG) in pure silica core single-mode fiber employing identical laser conditions. To reduce the high computational requirements, the beam envelope method approach is utilized in the aforementioned numerical models. The number of periods, grating length, and grating period considered in this work are numerically quantified. The numerically obtained spectral growth of the modeled LPFG seems to be consistent with the transmission of the experimentally fabricated LPFG single mode fiber. The sensing capabilities of the modeled LPFG are tested by varying the refractive index of the surrounding medium. The numerically obtained spectrum corresponding to the varied refractive index shows good agreement with the experimental findings.

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Characterization of refractive index change and fabrication of long period gratings in pure silica fiber by femtosecond laser radiation

Cited by 24 publications

References 31 publications

An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

Optical Fibre Long-Period Grating Sensors Operating at and around the Phase Matching Turning Point

Numerical Approach to Modeling and Characterization of Refractive Index Changes for a Long-Period Fiber Grating Fabricated by Femtosecond Laser

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