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Effect of Gamma-Ray Irradiation on the Growth of Au Nano-Particles Embedded in the Germano-Silicate Glass Cladding of the Silica Glass Fiber and its Surface Plasmon Resonance Response. SENSORS 2019; 19:s19071666. [PMID: 30965567 PMCID: PMC6480348 DOI: 10.3390/s19071666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/01/2019] [Accepted: 04/06/2019] [Indexed: 01/12/2023]
Abstract
The effect of γ-ray irradiation on the surface plasmon resonance (SPR) sensing capability of refractive index (n = 1.418–1.448) of the silica glass optical fiber comprised of germano-silicate glass cladding embedded with Au nano-particles (NPs) was investigated. As the γ-ray irradiation increased from 1 h to 3 h with the dose rate of 1190 Gy/h, the morphology of the Au NPs and the SPR spectrum were found to change. The average diameter of Au NPs increased with the aspect ratio from 1 to 2, and the nano-particles became grown to the clusters. The SPR band wavelength shifted towards a longer wavelength with the increase of total dose of γ-ray irradiation regardless of the corresponding refractive indices. The SPR sensitivities (wavelength/refractive index unit, nm/RIU) also increased from 407 nm/RIU to 3553 nm/RIU, 1483 nm/RIU, and 2335 nm/RIU after the γ-ray irradiation at a total dose of 1190 Gy, 2380 Gy, and 3570 Gy, respectively.
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2
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Wong RYN, Chehura E, Staines SE, James SW, Tatam RP. Fabrication of fiber optic long period gratings operating at the phase matching turning point using an ultraviolet laser. APPLIED OPTICS 2014; 53:4669-4674. [PMID: 25090202 DOI: 10.1364/ao.53.004669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 05/16/2014] [Indexed: 06/03/2023]
Abstract
It is known that optical fiber long period gratings (LPGs) exhibit their highest sensitivity to environmental perturbation when the period is such that the phase matching condition is satisfied at its turning point. The reproducible fabrication of LPGs with parameters satisfying this condition requires high resolution control over the properties of the grating. The performance of an LPG fabrication system based on the point-by-point UV exposure approach is analyzed in this paper, and the control of factors influencing reproducibility, including period, duty cycle, and the environment in which the device is fabricated, is explored.
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3
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Coelho JMP, Nespereira M, Abreu M, Rebordão J. 3D finite element model for writing long-period fiber gratings by CO2 laser radiation. SENSORS 2013; 13:10333-47. [PMID: 23941908 PMCID: PMC3812606 DOI: 10.3390/s130810333] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/06/2013] [Accepted: 08/08/2013] [Indexed: 11/29/2022]
Abstract
In the last years, mid-infrared radiation emitted by CO2 lasers has become increasing popular as a tool in the development of long-period fiber gratings. However, although the development and characterization of the resulting sensing devices have progressed quickly, further research is still necessary to consolidate functional models, especially regarding the interaction between laser radiation and the fiber's material. In this paper, a 3D finite element model is presented to simulate the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Dependence with temperature of the main parameters of the optical fiber materials (with special focus on the absorption of incident laser radiation) is considered, as well as convection and radiation losses. Thermal and residual stress analyses are made for a standard single mode fiber, and experimental results are presented.
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Affiliation(s)
- João M. P. Coelho
- Laboratory of Optics, Lasers and Systems, Faculty of Sciences, University of Lisbon, Campus do Lumiar, Estrada do Paço do Lumiar, 22, Building D, 1649-038 Lisboa, Portugal; E-Mails: (M.N.); (M.A.); (J.R.)
- Institute of Biophysics and Biomedical Engineering, Faculty of Sciences, University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Lisboa 1749-016, Portugal
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +351-217-500-759; Fax: +351-217-163-048
| | - Marta Nespereira
- Laboratory of Optics, Lasers and Systems, Faculty of Sciences, University of Lisbon, Campus do Lumiar, Estrada do Paço do Lumiar, 22, Building D, 1649-038 Lisboa, Portugal; E-Mails: (M.N.); (M.A.); (J.R.)
| | - Manuel Abreu
- Laboratory of Optics, Lasers and Systems, Faculty of Sciences, University of Lisbon, Campus do Lumiar, Estrada do Paço do Lumiar, 22, Building D, 1649-038 Lisboa, Portugal; E-Mails: (M.N.); (M.A.); (J.R.)
| | - José Rebordão
- Laboratory of Optics, Lasers and Systems, Faculty of Sciences, University of Lisbon, Campus do Lumiar, Estrada do Paço do Lumiar, 22, Building D, 1649-038 Lisboa, Portugal; E-Mails: (M.N.); (M.A.); (J.R.)
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4
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Hutsel MR, Gaylord TK. Residual-stress relaxation and densification in CO2-laser-induced long-period fiber gratings. APPLIED OPTICS 2012; 51:6179-6187. [PMID: 22945166 DOI: 10.1364/ao.51.006179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 07/19/2012] [Indexed: 06/01/2023]
Abstract
The first concurrent measurements of the three-dimensional refractive-index and residual-stress distributions in a CO(2)-laser-irradiated fiber are presented. A Corning SMF-28 fiber was exposed from one side to focused pulses with durations of 100-500 ms. The cross-sectional form of the index modulation is asymmetric with changes concentrated on the side of the fiber facing the exposure. The longitudinal form is Gaussian-like with a wide top and extends approximately 100 μm from the center of the exposure. Relaxation of frozen-in viscoelasticity results in a maximum index modulation of 5×10(-4) on the side of the fiber facing the exposure with mechanical stress relaxation contributing changes of less than 1×10(-4).
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Affiliation(s)
- Michael R Hutsel
- School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250, USA.
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Hutsel MR, Gaylord TK. Concurrent three-dimensional characterization of the refractive-index and residual-stress distributions in optical fibers. APPLIED OPTICS 2012; 51:5442-5452. [PMID: 22859034 DOI: 10.1364/ao.51.005442] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 06/27/2012] [Indexed: 06/01/2023]
Abstract
A three-dimensional index-stress distribution (3DISD) measurement method for determining concurrently the refractive-index distributions (RIDs) and residual-stress distributions (RSDs) in optical fibers is presented. The method combines the quantitative-phase microscopy technique, the Brace-Köhler compensator technique, and computed tomography principles. These techniques are implemented on a common apparatus to enable concurrent characterization of the RID and the RSD. Measurements are performed on Corning SMF-28 fiber in an unperturbed section and in a section exposed to CO(2) laser radiation. The concurrent measurements allow for the first accurate comparison of the collocated RID and RSD. The resolutions of the refractive index and stress are estimated to be 2.34×10(-5) and 0.35 MPa, respectively.
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Affiliation(s)
- Michael R Hutsel
- School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250, USA
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6
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Liu X, Zhan L, Luo S, Gu Z, Liu J, Shen Q. Spectrum evolution of cascaded mismatching long-period fiber gratings. APPLIED OPTICS 2012; 51:1367-1374. [PMID: 22441484 DOI: 10.1364/ao.51.001367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 12/08/2011] [Indexed: 05/31/2023]
Abstract
Two identical long-period fiber gratings (LPFGs) are difficult to produce in practice, notably for CO(2)-laser or arc-discharge induced LPFGs. So it is meaningful to study the spectrum evolution of cascaded LPFGs with some deviation, named "mismatching" LPFGs. Theory and experiment demonstrate that the upper envelope of the fringe pattern is intrinsically curved but less dramatically than the lower envelope. Bending the grating pair to introduce proper cladding-mode loss can improve the contrast of the fringe pattern at a desired wavelength, which indicates that cascaded mismatching LPFGs can be used as high-quality comb filters or fiber sensors.
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Affiliation(s)
- Xuesong Liu
- Department of Physics, Key Laboratory for Laser Plasmas (Ministry of Education), State Key Lab of Advanced Optical Communication Systems and Networks, Shanghai Jiao Tong University, Shanghai, 200240, China
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Li Y, Wei T, Montoya JA, Saini SV, Lan X, Tang X, Dong J, Xiao H. Measurement of CO2-laser-irradiation-induced refractive index modulation in single-mode fiber toward long-period fiber grating design and fabrication. APPLIED OPTICS 2008; 47:5296-5304. [PMID: 18846167 DOI: 10.1364/ao.47.005296] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report a new method to measure the CO(2)-laser-irradiation-induced refractive index modulation in the core of a single-mode optical fiber for the purpose of design and fabrication of long-period fiber gratings (LPFGs) without applying tension. Using an optical fiber Fabry-Perot interferometer, the laser-induced axial refractive index perturbation was measured. We found that the CO(2)-laser-irradiation-induced refractive index change in the fiber core had a negative value and that the magnitude was a sensitive function of the laser exposure time following almost a linear relation. Under the assumption of a Gaussian-shaped refractive index modulation profile and based on the first two terms of Fourier series approximation, the measured refractive index perturbations were used to simulate the LPFG transmission spectra. LPFGs with the same laser exposure parameters were fabricated without applying tension, and their spectra were compared with those obtained by simulations.
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Affiliation(s)
- Yanjun Li
- Department of Electrical and Computer Engineering, Missouri University of Science and Technology, 1870 Miner Circle, Rolla, Missouri 65409-0040, USA
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Liu Y, Chiang KS. CO(2) laser writing of long-period fiber gratings in optical fibers under tension. OPTICS LETTERS 2008; 33:1933-1935. [PMID: 18758569 DOI: 10.1364/ol.33.001933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We demonstrate experimentally that the efficiency of writing a long-period fiber grating in a single-mode fiber by CO(2) laser pulses increases significantly with the axial stress applied along the fiber. We attribute the enhancement in writing efficiency to the generation of nonuniform inelastic frozen-in strains across the fiber under tension by CO(2) laser heating. Controlling the axial stress distribution along a fiber during the CO(2) laser writing process thus provides an additional degree of freedom for control of the grating characteristics.
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Affiliation(s)
- Yunqi Liu
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong.
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Montarou CC, Gaylord TK, Bachim BL, Dachevski AI, Agarwal A. Two-wave-plate compensator method for full-field retardation measurements. APPLIED OPTICS 2006; 45:271-80. [PMID: 16422157 DOI: 10.1364/ao.45.000271] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The two-wave-plate compensator (TWC) method is expanded for full-field retardation measurements by use of a polarization microscope. The sample image is projected onto a CCD camera connected to a computer, allowing the retardation to be measured at all pixels. The retardation accuracy of this implementation of the TWC is evaluated to be 0.06 nm. The method is applied to polarization-maintaining fibers and long-period fiber gratings. The measured retardation is in good agreement with the crossed-polarizer images of the fibers. The method achieves a spatial resolution of 0.45 microm and a retardation resolution of 0.07 nm. The full-field TWC method can thus be a useful tool for characterizing and monitoring the fabrication of optical devices.
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Affiliation(s)
- Carole C Montarou
- School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250, USA
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Yokouchi T, Suzaki Y, Nakagawa K, Yamauchi M, Kimura M, Mizutani Y, Kimura S, Ejima S. Thermal tuning of mechanically induced long-period fiber grating. APPLIED OPTICS 2005; 44:5024-8. [PMID: 16121785 DOI: 10.1364/ao.44.005024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We have developed a wideband tunable optical filter that uses a long-period fiber grating (LPFG) in which both resonance wavelength and its signal attenuation can be adjusted. We create the grating mechanically by pressing a spring coil to an optical fiber. We achieve continuous fine tuning of wavelength and attenuation by varying the temperature of the LPFG. The adjustable ranges of the LPFG are more than 200 nm in resonance wavelength and more than 10 dB in signal attenuation.
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Affiliation(s)
- Takashi Yokouchi
- Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa, 761-0396 Japan
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Zhu Y, Shum P, Bay HW, Yan M, Yu X, Hu J, Hao J, Lu C. Strain-insensitive and high-temperature long-period gratings inscribed in photonic crystal fiber. OPTICS LETTERS 2005; 30:367-369. [PMID: 15762430 DOI: 10.1364/ol.30.000367] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We fabricate and demonstrate strain-insensitive and high-temperature long-period gratings in endlessly single-mode photonic crystal fiber by use of focused pulses of a CO2 laser and a periodic stress relaxation technique without geometrical deformation and elongation of the fiber. The thermal dependence of mode coupling at 1299.59 nm is 10.9 pm/degrees C from 24 to 992 degrees C, whereas the coefficient of strain sensitivity is -0.192 pm/muepsilon up to the maximum strain of 2.74%epsilon. It is found for what is believed to be the first time that, in contrast with the traditional fiber case, the coupling resonance shifts toward shorter wavelengths under applied strain, indicating that the refractive index of the core is decreased as a result of the rebuilding of tension attributed to the stress-elastic effect, and the cladding modes is highly dispersive because of airholes arranged in the fiber cladding.
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Affiliation(s)
- Yinian Zhu
- Network Technology Research Center, Nanyang Technological University, 50 Nanyang Drive, Research TechnoPlaza, Singapore 637553.
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Montarou CC, Gaylord TK. Two-wave-plate compensator method for single-point retardation measurements. APPLIED OPTICS 2004; 43:6580-6595. [PMID: 15646778 DOI: 10.1364/ao.43.006580] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The two-wave-plate compensator (TWC) technique is introduced for single-point retardation measurements. The TWC method uses a known wave plate together with a wave plate of unknown retardation and produces a linearly polarized output that allows a null of intensity to be detected. The TWC method is compared both theoretically and experimentally with the existing Brace-Köhler and Sénarmont methods. The resolution of the TWC is shown to be 0.02 nm. TWC enables the measurement of a sample retardation with as little as 0.13% error and thus is more accurate than either the Brace-Kohler or the Sénarmont method.
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Affiliation(s)
- Carole C Montarou
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250, USA
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Zhu Y, Shum P, Bay HW, Chen X, Tan CH, Lu C. Wide-passband, temperature-insensitive, and compact pi-phase-shifted long-period gratings in endlessly single-mode photonic crystal fiber. OPTICS LETTERS 2004; 29:2608-2610. [PMID: 15552660 DOI: 10.1364/ol.29.002608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We demonstrate what is believed to be the first fabrication of a wide-passband, temperature-insensitive, and compact spectral filter based on a pi-phase-shifted long-period grating in an endless single-mode photonic crystal fiber. By introducing a pi-phase shift in the middle of a 12-period long-period grating, two symmetrical rejection bands at wavelengths of 1252.65 and 1418.7 nm are obtained with isolation higher than 18 dB and a passband bandwidth of 84.15 nm. The pi-phase-shifted long-period gratings are inscribed by the relaxation of mechanical stress with the focused pulses of a CO2 laser and a point-by-point technique without geometric deformation. The length of the spectral filter is approximately 6.6 mm with a sensitivity of 8 pm/ degrees C at a medium temperature range of 23-190 degrees C.
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Affiliation(s)
- Yinian Zhu
- Network Technology Research Center, Nanyang Technological University, 50 Nanyang Drive, Research TechnoPlaza, Singapore 637553.
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