Mode transition in high refractive index coated long period gratings

Cusano, A.; Iadicicco, Agostino; Pilla, P.; Contessa, L.; Campopiano, Stefania; Cutolo, A.; Giordano, M.

doi:10.1364/opex.14.000019

Cited by 249 publications

(154 citation statements)

References 30 publications

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“…Depending on the boundary condition between the cladding and the surrounding medium, the cladding modes propagate in a different manner [8][9][10][11][12][13]. In air, the cladding modes experience a total internal reflection (TIR) mechanism at the interface between the cladding and air.…”

Section: Principle Of Operationmentioning

confidence: 99%

“…Due to the refractive-reflective regime at the cladding-layer interface, the cladding modes in a LPFG, surrounded by nanosized HRI layer, are bound within the structure comprising the core, the cladding and the layer. It has been already proven that changes in the thickness of the nanosized HRI layer led to a significant shift of the attenuation bands in the transmission spectrum of the LPFG [11][12][13]…”

Section: Principle Of Operationmentioning

confidence: 99%

“…For such an infinite thickness of the high refractive index (HRI) medium, a sufficient tuning of the resonant wavelengths of the LPFG versus the SRI is very difficult. A strong improvement in the LPFGs sensitivity can be obtained by reducing the thickness of the HRI medium to nanosize [11][12][13]. When a nanosized HRI layer is deposited along the LPFG, a significant modification of the distribution of cladding modes occurs leading to considerable shifts of the resonance wavelengths.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Novel Electrically Tunable Long-Period Fiber Grating Using a Liquid Crystal Cladding Layer

Czapla

Woliński

Nowinowski-Kruszelnicki

et al. 2010

Acta Phys. Pol. A

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The main aim of the presented work is the integration of a long-period fiber grating and a liquid crystal into a hybrid structure, in order to develop an innovative fiber optic device controlled by an external electric field. The studied long-period fiber grating was fabricated using UV irradiation in a boron co-doped fiber (PS1250/ 1500, manufactured by Fibercore). As a liquid crystal we used a typical 5CB nematic liquid crystal. The sensing mechanism of the proposed loss filter relies on long-period fiber grating attenuation bands sensitivity to optical properties of the liquid crystal layer. The results obtained show that the long-period fiber grating with a nanosized liquid crystal layer exhibits one order of magnitude higher electrical sensitivity and a lower level of the voltage control than the long-period fiber grating with a micro-sized liquid crystal layer.PACS IntroductionIn order to achieve light coupling between two co--propagating modes, a grating formed in an optical fiber usually requires a pitch of several hundred micrometers. This type of grating is called a long-period fiber grating (LPFG). Compared to other optical devices, LPFGs have a number of unique advantages such as low-level back reflection, low insertion losses and compact construction (the grating is an intrinsic fiber device). The LPFGs have found a variety of applications in optical communications [1,2]. Tuning of the LPFGs is very attractive since it can offer a form of dynamic spectral control [3,4]. The central attenuation wavelength of the LPFGs is highly sensitive to temperature, strain, bend or surrounding refractive index (SRI) changes. For these reasons filters based on the LPFGs have generated a significant interest for applications in the sensing field as well.Liquid crystals (LCs) are attractive candidates as a coating material since their properties can be controlled through temperature, optical, electrical and magnetic fields [5][6][7]. There are three key points for a good design in order to combine a LPFG and a LC into one component: selection of the LC refractive indices, inherent SRI sensitivity of the LPFG and the LC layer thickness. Majority of LCs have refractive indices that are higher than the refractive index of the silica glass. Thus, the LPFG sensitive to SRI is limited to the range where SRI is higher than the refractive index of the fiber cladding. In this case, the core modes couple to leaky modes [8] and the dependence on the resonance wavelength on the SRI is not so straightforward. So far, most of the studies have focused on the analysis of the SRI sensitivity when the

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Section: Principle Of Operationmentioning

confidence: 99%

Section: Principle Of Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Electrically Tunable Long-Period Fiber Grating Using a Liquid Crystal Cladding Layer

Czapla

Woliński

Nowinowski-Kruszelnicki

et al. 2010

Acta Phys. Pol. A

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“…Long period fiber gratings (LPFG) can be used as highly sensitive detectors by application of three different phenomena: the mode transition [1,2], the dispersion turning point (DTP) [3], and the reduction of the cladding diameter [4,5]. It has been theoretically analyzed that a sensitivity in the water region of up to 143,000 nm/refractive index unit (nm/RIU) can be attained by considering the wavelength shift of both attenuation bands in DTP mode [6].…”

Section: Introductionmentioning

confidence: 99%

Monitoring the Etching Process in LPFGs towards Development of Highly Sensitive Sensors

Villar

Cruz

Socorro

et al. 2017

Proceedings of Eurosensors 2017, Paris, France, 3–6 September 2017

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Abstract:In this work, the monitoring of the etching process up to a diameter of 30 µm of two LPFG structures has been compared, one of them had initially 125 µm, whereas the second one had 80 µm. By tracking the wavelength shift of the resonance bands during the etching process it is possible to check the quality of etching process (the 80 µm fibre performs better than de 125 µm fibre), and to stop for a specific cladding mode coupling, which permits to obtain an improved sensitivity compared to the initial structure.

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“…For instance several approaches have been proposed to achieve remarkable sensitivities such as cladding etching, LPG design for coupling to higher order modes near their dispersion turning points or in-fiber complex configuration including multi-gratings (Chung & Yin, 2004;Iadicicco et al, 2007Iadicicco et al, , 2008Pilla et al, 2008). Additionally, once the effects of depositing a thin high RI (HRI) layer onto the cladding over the grating region have been discovered, huge sensitivity enhancements in comparison to bare LPGs have been obtained due to the so-called modal transition (Del Villar et al, 2005;Cusano et al, , 2006a. On the other side, it is worth noting that new fiber designs such as D-shaped fibers and photonic crystal fibers (PCFs) (with solid and air core) capable to offer new perspective in sensing and telecommunications applications have attracted the attention of several researcher groups and scientists (Tseng & Chen, 1992;Smith et al, 2004;Gordon et al, 2007;Kaiser et al, 1974;Knight et al, 1996).…”

Section: Introductionmentioning

confidence: 99%