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Rego G, Caldas P, Ivanov OV. Arc-Induced Long-Period Fiber Gratings at INESC TEC. Part I: Fabrication, Characterization and Mechanisms of Formation. SENSORS (BASEL, SWITZERLAND) 2021; 21:4914. [PMID: 34300654 PMCID: PMC8309710 DOI: 10.3390/s21144914] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/03/2022]
Abstract
In this work, we reviewed the most important achievements of INESC TEC related to the fabrication of long-period fiber gratings using the electric arc technique. We focused on the fabrication setup, the type of fiber used, and the effect of the fabrication parameters on the gratings' transmission spectra. The theory was presented, as well as a discussion on the mechanisms responsible for the formation of the gratings, supported by the measurement of the temperature reached by the fiber during an electric arc discharge.
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Affiliation(s)
- Gaspar Rego
- proMetheus, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial Nun’Álvares, 4900-347 Viana do Castelo, Portugal;
- Center for Applied Photonics, INESC TEC, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Paulo Caldas
- proMetheus, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial Nun’Álvares, 4900-347 Viana do Castelo, Portugal;
- Center for Applied Photonics, INESC TEC, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Oleg V. Ivanov
- Ulyanovsk Branch of Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Ulitsa Goncharova 48, 432071 Ulyanovsk, Russia;
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2
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Liu Z, Liu Y, Zhao X, Mou C. Bandwidth optimization of cascaded long-period gratings for broadband mode conversion over 1.0-2.2 µm waveband. OPTICS EXPRESS 2020; 28:31882-31892. [PMID: 33115152 DOI: 10.1364/oe.408623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 09/30/2020] [Indexed: 06/11/2023]
Abstract
We investigated theoretically and experimentally the cascaded long-period fiber gratings (c-LPFGs) in a few-mode fiber (FMF) for the generation of LP11 core mode in a broad wavelength range. The dependence of the transmission spectra of the c-LPFGs on the spacing between the gratings, and grating periods are studied in detail. The c-LPFGs experimentally generate LP11 core mode in a 10-dB bandwidth of 193.6 nm in 1.55 µm waveband and 447.5 nm in 2 µm waveband, respectively. The first-order orbital angular momentum mode can be converted by the c-LPFGs with the same broadband wavelength range. The 10-dB bandwidth and corresponding wavelength range for mode conversion can be adjusted by changing the grating spacing and grating periods.
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3
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Høvik J, Yadav M, Wook Noh J, Aksnes A. Waveguide asymmetric long-period grating couplers as refractive index sensors. OPTICS EXPRESS 2020; 28:23936-23949. [PMID: 32752382 DOI: 10.1364/oe.397561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/04/2020] [Indexed: 06/11/2023]
Abstract
A highly sensitive integrated photonic transducer is designed by utilizing asymmetric long-period gratings on a silicon waveguide. These gratings are formed by periodic perturbation of the waveguide width, leading to coupling between the fundamental mode and the 1st order asymmetric leaky mode. The coupled modes are studied via finite-element and finite-difference time-domain methods. Only a single fabrication step is required to realize this novel design. The device is utilized as a refractive index sensor in liquid, yielding a sensitivity of 5078 nm/RIU. The design is a unique combination of being highly sensitive, easily fabricated and highly compact.
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4
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Bao Y, Huang Y, Hoehler MS, Chen G. Review of Fiber Optic Sensors for Structural Fire Engineering. SENSORS (BASEL, SWITZERLAND) 2019; 19:E877. [PMID: 30791563 PMCID: PMC6412206 DOI: 10.3390/s19040877] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/14/2019] [Accepted: 02/17/2019] [Indexed: 11/17/2022]
Abstract
Reliable and accurate measurements of temperature and strain in structures subjected to fire can be difficult to obtain using traditional sensing technologies based on electrical signals. Fiber optic sensors, which are based on light signals, solve many of the problems of monitoring structures in high temperature environments; however, they present their own challenges. This paper, which is intended for structural engineers new to fiber optic sensors, reviews various fiber optic sensors that have been used to make measurements in structure fires, including the sensing principles, fabrication, key characteristics, and recently-reported applications. Three categories of fiber optic sensors are reviewed: Grating-based sensors, interferometer sensors, and distributed sensors.
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Affiliation(s)
- Yi Bao
- Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, NJ 07030, USA.
| | - Ying Huang
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58105, USA.
| | - Matthew S Hoehler
- National Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Genda Chen
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA.
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5
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Li Z, Liu S, Bai Z, Fu C, Zhang Y, Sun Z, Liu X, Wang Y. Residual-stress-induced helical long period fiber gratings for sensing applications. OPTICS EXPRESS 2018; 26:24114-24123. [PMID: 30184903 DOI: 10.1364/oe.26.024114] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate a high-efficiency grating fabrication system, which can be used to inscribe a high-quality helical long period fiber grating (HLPFG) on single-mode fiber by means of hydrogen-oxygen flame. Such the HLPFG can be produced in enormous quantities with a uniform grating parameters and good reproducibility of grating inscription. Possible mechanisms for refractive index modulation in the HLPFG can be attributed to residual stress concentration by solidifying the periodic twisting stress under a fused status of optical fiber. Moreover, the HLPFG exhibits an excellence performance of high temperature sensing with a high sensitivity of ~132.8 pm/°C and a measuring range from room temperature to 900 °C. Comparing to the traditional LPFG fabricated by CO2 laser or arc discharge technique, the HLPFG has a low the bending and tensile strain sensitivity of 1.94 nm/(1/m) and 1.41 pm/με, respectively. So the proposed HLPFG could have a great potential in special applications as optical high-temperature sensors.
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6
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Zhao Y, Huang S, Cui Z, Chai Q, Liu Y, Ren J, Zhang J, Lewis E, Liu Z, Yang J, Yuan L. Electric-arc-induced strength-controllable weak polarization mode coupling in polarization maintaining fiber. APPLIED OPTICS 2018; 57:6446-6450. [PMID: 30117876 DOI: 10.1364/ao.57.006446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/02/2018] [Indexed: 06/08/2023]
Abstract
An electric-arc-based scheme to generate strength-controllable weak polarization mode coupling (PMC) points in polarization maintaining fiber (PMF) is described. The resulting PMC strengths can be readily controlled to be in the very weak range of -60 to -40 dB. In this range, excellent mechanical strength combined with high return loss is achieved. An experimental quasi-distributed temperature sensor is formed by three separate PMC points in a single PMF using the electric arc method.
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7
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Long-Period Gratings in Highly Germanium-Doped, Single-Mode Optical Fibers for Sensing Applications. SENSORS 2018; 18:s18051363. [PMID: 29702600 PMCID: PMC5982642 DOI: 10.3390/s18051363] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/19/2018] [Accepted: 04/25/2018] [Indexed: 11/16/2022]
Abstract
Long-period fiber gratings (LPGs) are well known for their sensitivity to external influences, which make them interesting for a large number of sensing applications. For these applications, fibers with a high numerical aperture (i.e., fibers with highly germanium (Ge)-doped fused silica fiber cores) are more attractive since they are intrinsically photosensitive, as well as less sensitive to bend- and microbend-induced light attenuations. In this work, we introduce a novel method to inscribe LPGs into highly Ge-doped, single-mode fibers. By tapering the optical fiber, and thus, tailoring the effective indices of the core and cladding modes, for the first time, an LPG was inscribed into such fibers using the amplitude mask technique and a KrF excimer laser. Based on this novel method, sensitive LPG-based fiber optic sensors only a few millimeters in length can be incorporated in bend-insensitive fibers for use in various monitoring applications. Moreover, by applying the described inscription method, the LPG spectrum can be influenced and tailored according to the specific demands of a particular application.
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Esposito F, Ranjan R, Campopiano S, Iadicicco A. Arc-Induced Long Period Gratings from Standard to Polarization-Maintaining and Photonic Crystal Fibers. SENSORS 2018; 18:s18030918. [PMID: 29558407 PMCID: PMC5877216 DOI: 10.3390/s18030918] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/15/2018] [Accepted: 03/18/2018] [Indexed: 11/29/2022]
Abstract
In this work, we report about our recent results concerning the fabrication of Long Period Grating (LPG) sensors in several optical fibers, through the Electric Arc Discharge (EAD) technique. In particular, the following silica fibers with both different dopants and geometrical structures are considered: standard Ge-doped, photosensitive B/Ge codoped, P-doped, pure-silica core with F-doped cladding, Panda type Polarization-maintaining, and Hollow core Photonic crystal fiber. An adaptive platform was developed and the appropriate “recipe” was identified for each fiber, in terms of both arc discharge parameters and setup arrangement, for manufacturing LPGs with strong and narrow attenuation bands, low insertion losses, and short length. As the fabricated devices have appealing features from the application point of view, the sensitivity characteristics towards changes in different external perturbations (i.e., surrounding refractive index, temperature, and strain) are investigated and compared, highlighting the effects of different fiber composition and structure.
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Affiliation(s)
- Flavio Esposito
- Department of Engineering, University of Naples "Parthenope", Centro Direzionale Isola C4, 80143 Napoli, Italy.
| | - Rajeev Ranjan
- Department of Engineering, University of Naples "Parthenope", Centro Direzionale Isola C4, 80143 Napoli, Italy.
- Institute for Microelectronics and Microsystems, National Research Council, 80131 Napoli, Italy.
| | - Stefania Campopiano
- Department of Engineering, University of Naples "Parthenope", Centro Direzionale Isola C4, 80143 Napoli, Italy.
| | - Agostino Iadicicco
- Department of Engineering, University of Naples "Parthenope", Centro Direzionale Isola C4, 80143 Napoli, Italy.
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9
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Real-time analysis of arc-induced Long Period Gratings under gamma irradiation. Sci Rep 2017; 7:43389. [PMID: 28262784 PMCID: PMC5338260 DOI: 10.1038/srep43389] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/23/2017] [Indexed: 11/09/2022] Open
Abstract
In this paper, we present a comparative experimental and theoretical study on gamma radiation sensitivity of Long Period Gratings (LPGs), fabricated by electric arc discharge technique, as monitored in three single mode optical fibers supplied by different manufacturers. A real-time measurement of LPGs’ wavelength shift was performed until a total dose of 35 kGy was reached, with average dose rate of 0.18 kGy/h, the irradiation being done at room temperature. In one case, a maximum radiation sensitivity of 1.34 nm/kGy was recorded for doses up to 0.5 kGy. Moreover, by combining experimental results with numerical simulations, it was found that changes occurred in the core refractive index of the irradiated optical fibers up to 2.5 ∙ 10−5. The increase of the core thermo-optic coefficient up to 1.5 ∙ 10−8/°C was observed as well.
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10
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Wang P, Gaylord TK. Dissimilar-fiber long-period fiber gratings: concept and demonstration. APPLIED OPTICS 2017; 56:1142-1147. [PMID: 28158126 DOI: 10.1364/ao.56.001142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A new type of long-period fiber grating structure that contains dissimilar fiber types is proposed. This dissimilar-fiber long-period fiber grating (DF-LPFG) structure is fabricated by splicing together subperiod sections of dissimilar fiber types. Due to the large index differences that can exist between various fiber types, the resulting DF-LPFGs can be exceptionally short, e.g., a few millimeters. As a demonstration, prototype DF-LPFGs were fabricated by periodically splicing together standard single-mode fiber and dispersion-compensating fiber using a commercially available cleaver and splicer. The resulting DF-LPFGs exhibited clear resonances with attenuations of ∼35 dB and insertion losses of ∼8 dB. To the best of the authors' knowledge, this is the first demonstration of the DF-LPFG concept. Other devices based on this concept may also be realizable.
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11
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Wang P, Jenkins MH, Gaylord TK. Arc-discharge effects on residual stress and refractive index in single-mode optical fibers. APPLIED OPTICS 2016; 55:2451-2456. [PMID: 27140587 DOI: 10.1364/ao.55.002451] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Arc-discharge effects on the residual stress and refractive index in single-mode optical fibers are investigated using a previously developed three-dimensional concurrent stress-index measurement method. Using commercial optical fibers and a commercial fusion splicer, the residual stress and refractive index perturbations caused by weak electrical arc discharges in single-mode fibers were measured. Refractive index changes greater than 10-4 and longitudinal perturbation lengths of less than 500 μm were shown to be possible. The subsequent prospects for arc-induced long-period fiber gratings are analyzed, and a typical transmission resonance is predicted to have a depth of 56 dB and a bandwidth of 0.08 nm at a wavelength of 1585 nm. The results of this investigation will be useful in modeling device performance and optimization of arc-induced long-period fiber grating fabrication.
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12
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Chiang CC, Li CH. A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating. OPTICS EXPRESS 2014; 22:13916-13926. [PMID: 24921583 DOI: 10.1364/oe.22.013916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/με, and that an R2 value of 0.963 was reached.
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13
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Schimpf DN, Putnam WP, Grogan MDW, Ramachandran S, Kärtner FX. Radially polarized Bessel-Gauss beams: decentered Gaussian beam analysis and experimental verification. OPTICS EXPRESS 2013; 21:18469-18483. [PMID: 23938719 DOI: 10.1364/oe.21.018469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We derive solutions for radially polarized Bessel-Gauss beams in free-space by superimposing decentered Gaussian beams with differing polarization states. We numerically show that the analytical result is applicable even for large semi-aperture angles, and we experimentally confirm the analytical expression by employing a fiber-based mode-converter.
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Affiliation(s)
- Damian N Schimpf
- Department of Electrical Engineering and Computer Science, Research Lab. of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
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14
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High temperature optical fiber sensor based on compact fattened long-period fiber gratings. SENSORS 2013; 13:3028-38. [PMID: 23459386 PMCID: PMC3658729 DOI: 10.3390/s130303028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 02/15/2013] [Accepted: 02/22/2013] [Indexed: 11/17/2022]
Abstract
A compact high temperature fiber sensor where the sensor head consists of a short fattened long period fiber grating (F-LPFG) of at least 2 mm in length and background loss of −5 dBm is reported. On purpose two different F-LPFGs were used to measure temperature variations, taking advantage of their broad spectrum and the slope characteristics of the erbium light source. This approach affected the spectrum gain as the linear band shifting took place. The measured sensitivity of the long period fiber gratings were about 72 pm/°C in a range from 25 to 500 °C. Here, the temperature rate of the experiment was 0.17 °C/s and the temperature response time was within 3 s. Moreover, temperature changes were detected with an InGaAs photodetector, where a sensitivity of 0.05 mV/°C was achieved.
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15
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Sun LP, Li J, Jin L, Guan BO. Structural microfiber long-period gratings. OPTICS EXPRESS 2012; 20:18079-18084. [PMID: 23038355 DOI: 10.1364/oe.20.018079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We experimentally demonstrate a novel structural long-period grating by helically coiling one microfiber onto another with the relatively thicker diameter. Owing to the strong periodic modulation of the coiled microfiber to the evanescent field of the straight microfiber, a resonance transmission notch of ~16.2 dB can be induced for a compact device length of ~450 μm only (4 helical periods). Moreover, the filtered light energy from the straight fiber can emerge again at the output of the coiled one, providing great flexibility in producing new device functions. The spectral response to external strain is investigated and wide wavelength tuning range of around 106 nm is discussed.
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Affiliation(s)
- Li-Peng Sun
- Institute of Photonics Technology, Jinan University, Guangzhou 510632, China
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16
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Yang RZ, Dong WF, Meng X, Zhang XL, Sun YL, Hao YW, Guo JC, Zhang WY, Yu YS, Song JF, Qi ZM, Sun HB. Nanoporous TiO2/polyion thin-film-coated long-period grating sensors for the direct measurement of low-molecular-weight analytes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8814-8821. [PMID: 22594626 DOI: 10.1021/la301445h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present novel nanoporous TiO(2)/polyion thin-film-coated long-period fiber grating (LPFG) sensors for the direct measurement of low-molecular-weight chemicals by monitoring the resonance wavelength shift. The hybrid overlay films are prepared by a simple layer-by-layer deposition approach, which is mainly based on the electrostatic interaction of TiO(2) nanoparticles and polyions. By the alternate immersion of LPFG into dispersions of TiO(2) nanoparticles and polyions, respectively, the so-formed TiO(2)/polyion thin film exhibits a unique nanoporous internal structure and has a relative higher refractive index than LPFG cladding. In particular, the porosity of the thin film reduces the diffusion coefficient and enhances the permeability retention of low-molecular-weight analytes within the porous film. The increases in the refractive index of the LPFG overlay results in a distinguished modulation of the resonance wavelength. Therefore, the detection sensitivity of LPFG sensors has been greatly improved, according to theoretical simulation. After the structure of the TiO(2)/polyion thin film was optimized, glucose solutions as an example with a low concentration of 10(-7) M was easily detected and monitored at room temperature.
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Affiliation(s)
- Rui-Zhu Yang
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
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Sakata H, Yamahata K. Magnetic-force-induced long-period fiber gratings. OPTICS LETTERS 2012; 37:1250-1252. [PMID: 22466211 DOI: 10.1364/ol.37.001250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A novel formation method of a long-period fiber grating (LPFG) based on a magnetic-force-induced microbend is proposed and experimentally demonstrated. The LPFG employs a permanent magnet that exerts transversal force to the fiber by attracting a steel coil spring. The transversal force causes periodic microbending to the fiber, and therefore the transmission wave attenuates at the core-to-cladding mode resonance. This device has advantages of ease of fabrication, reconfigurability, and available for any type of fiber.
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Affiliation(s)
- Hajime Sakata
- Department of Electrical and Electronic Engineering, Shizuoka University, Naka-ku, Hamamatsu, Japan.
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18
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Wang HY, Chuo SM, Huang CY, Wang LA. Embedded corrugated long-period fiber gratings for sensing applications. APPLIED OPTICS 2012; 51:1453-1458. [PMID: 22505062 DOI: 10.1364/ao.51.001453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 01/06/2012] [Indexed: 05/31/2023]
Abstract
We demonstrate a method to make possible the mass production of corrugated long-period fiber gratings (C-LPFGs) by utilizing imprint lithography on polycarbonate (PC) substrates. For such C-LPFGs whose working principle is based on photoelastic effect, pretensile tension is required to be applied to inducing periodical refractive index variation. We then present an attempt to use PC as embedding material for providing internal compressive stress for C-LPFGs to have a photoelastic effect. This type of LPFG, termed embedded corrugated long-period fiber gratings (EC-LPFGs), is obtained after reimprinting the C-LPFGs into other PC substrates. Since compressive stress is retained due to the materials of different coefficients of thermal expansion (CTE), unlike C-LPFGs, EC-LPFGs can serve as strain, bending, and temperature sensors without the need of pretensile strain. The two most troublesome problems, the fragility of an etched fiber grating and the requirement of pretensile strain, can be simultaneously alleviated or solved by EC-LPFGs.
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Affiliation(s)
- Hsiao-Yuh Wang
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan
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Sakata H, Araki S, Toyama R, Tomiki M. All-fiber Q-switched operation of thulium-doped silica fiber laser by piezoelectric microbending. APPLIED OPTICS 2012; 51:1067-1070. [PMID: 22410984 DOI: 10.1364/ao.51.001067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/04/2012] [Indexed: 05/31/2023]
Abstract
We demonstrate an all-fiber Q-switched laser operation in the 2 µm region on the basis of a dynamic periodic microbend and pulsed-pump configuration. A single-mode thulium-doped silica fiber is pumped by 1.6 µm-band laser diodes, and the dynamic loss is introduced in the fiber ring resonator by the periodic microbend that is electrically controlled with a piezoelectric actuator. When the voltage-off period of the piezoelectric actuator is set at 20 µs for the pump power of 120 mW, the output pulse power is measured by 420 mW with a pulse width of 1.3 µs.
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Affiliation(s)
- Hajime Sakata
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, Naka-ku, Hamamatsu, Japan.
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20
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Wu Z, Wang Z, Liu YG, Han T, Li S, Wei H. Mechanism and characteristics of long period fiber gratings in simplified hollow-core photonic crystal fibers. OPTICS EXPRESS 2011; 19:17344-17349. [PMID: 21935098 DOI: 10.1364/oe.19.017344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate the fabrication of high-quality LPFGs in simplified hollow-core photonic crystal fibers, composed of a hollow hexagonal core and six crown-like air holes, using CO2-laser-irradiation method. Theoretical and experimental investigations indicate that the LPFGs are originated from the strong mode-coupling between the LP01 and LP11 core modes. And a dominant physical mechanism for the mode-coupling is experimentally confirmed to be the periodic microbends rather than the deformations of the cross-section or other common factors. In addition, the LPFGs are highly sensitive to strain and nearly insensitive to temperature, and are promising candidates for gas sensors and nonlinear optical devices.
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Affiliation(s)
- Zhifang Wu
- Key Laboratory of Optical Information and Technology, Ministry of Education and Institute of Modern Optics, Nankai University, Tianjin, China
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21
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Wang K, Pickrell G. Long period gratings in random hole optical fibers for refractive index sensing. SENSORS (BASEL, SWITZERLAND) 2011; 11:1558-1564. [PMID: 22319368 PMCID: PMC3274026 DOI: 10.3390/s110201558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 01/18/2011] [Accepted: 01/19/2011] [Indexed: 05/31/2023]
Abstract
We have demonstrated the fabrication of long period gratings in random hole optical fibers. The long period gratings are fabricated by a point-by-point technique using a CO(2) laser. The gratings with a periodicity of 450 μm are fabricated and a maximum coupling efficiency of -9.81 dB has been achieved. Sensing of different refractive indices in the surrounding mediums is demonstrated by applying standard liquids with refractive indices from 1.400 to 1.440 to the long period grating.
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Affiliation(s)
- Ke Wang
- Center for Photonics Technology, Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
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22
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Sakata H, Ichikawa M, Nakagami H. Tunable Tm-doped fiber ring laser operating at 1.9 μm band using force-induced fiber grating as wavelength tuner. APPLIED OPTICS 2011; 50:291-295. [PMID: 21263724 DOI: 10.1364/ao.50.000291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report wavelength-tunable operation of a Tm-doped silica fiber laser by using a force-induced long-period fiber grating (LPFG) formed in a fiber ring resonator. The laser output wavelength is tuned by moving the transmission passband that is generated between adjacent resonance wavelengths due to the force-induced LPFG. By changing the grating period around 900 μm, we control the laser output wavelength between 1845 and 1930 nm.
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Affiliation(s)
- Hajime Sakata
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561, Japan.
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Sakata H, Nishio K, Ichikawa M. Tunable bandpass filter based on force-induced long-period fiber grating in a double cladding fiber. OPTICS LETTERS 2010; 35:1061-1063. [PMID: 20364217 DOI: 10.1364/ol.35.001061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present an all-fiber tunable bandpass filter based on a combination of a force-induced long-period fiber grating and a fiber coil made along a double cladding fiber. The transmission wavelength can be tuned to be in a range of more than 100 nm by changing the grating period mechanically. We can control the transmission amplitude of the bandpass filter by adjusting the periodic force on the double cladding fiber. The ambient temperature causes a positive shift in the transmission wavelength. Such a device is useful for tunable laser applications and fiber-optic sensors.
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Affiliation(s)
- Hajime Sakata
- Department of Electrical and Electronic Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561, Japan.
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Xuan H, Jin W, Zhang M. CO2 laser induced long period gratings in optical microfibers. OPTICS EXPRESS 2009; 17:21882-21890. [PMID: 19997432 DOI: 10.1364/oe.17.021882] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Long period gratings (LPGs) are fabricated by use of focused high frequency CO(2) laser pulses to periodically modify the transverse dimension of silica microfibers. A 20-period LPG with a 27 dB attenuation dip is realized in a microfiber with a diameter of approximately 6.3 microm. The resonant wavelength has a negative temperature coefficient and a high sensitivity to external refractive index. The microfiber LPGs may be useful in micron scale in-fiber devices and sensors.
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Affiliation(s)
- Haifeng Xuan
- Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong
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25
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Pilla P, Foglia Manzillo P, Giordano M, Korwin-Pawlowski ML, Bock WJ, Cusano A. Spectral behavior of thin film coated cascaded tapered long period gratings in multiple configurations. OPTICS EXPRESS 2008; 16:9765-9780. [PMID: 18575545 DOI: 10.1364/oe.16.009765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this work the spectral response of cascaded tapered long period gratings coated by nano-sized polymeric films has been investigated as function of the surrounding medium refractive index (SRI). The investigation was aimed to identify the best configuration in terms of coated/not coated areas in order to fully benefit of the SRI sensitivity enhancement due to the modal transition mechanism of nano-coated long period gratings while preserving the fringes visibility.
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Affiliation(s)
- P Pilla
- Optoelectonic Division, Engineering Department, University of Sannio, Benevento, Italy.
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26
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Shao LY, Zhao J, Dong X, Tam HY, Lu C, He S. Long-period grating fabricated by periodically tapering standard single-mode fiber. APPLIED OPTICS 2008; 47:1549-1552. [PMID: 18382584 DOI: 10.1364/ao.47.001549] [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 fabricated an asymmetric long-period grating (LPG) by periodically tapering a section of standard single-mode fiber using a resistive filament heating. The LPG exhibits large peak transmission attenuation of -30.31 dB with only 22 periods in a 1.0 cm long optical fiber and possesses unique characteristics for sensing applications. The bending and strain sensitivities are 1.74 nm m and 1.11 pm/mu epsilon, respectively. The polarization dependent loss is large, up to 11.65 dB, which is caused by an asymmetric index profile in the cross section of the tapered LPG.
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Affiliation(s)
- Li-Yang Shao
- Center for Optical and Electromagnetic Research, Zhejiang University, Hangzhou, Zhejiang, China.
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27
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Wang Y, Wang DN, Jin W, Rao Y. Asymmetric transverse-load characteristics and polarization dependence of long-period fiber gratings written by a focused CO(2) laser. APPLIED OPTICS 2007; 46:3079-86. [PMID: 17514259 DOI: 10.1364/ao.46.003079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Asymmetric transverse-load characteristics and the polarization dependence of long-period fiber gratings (LPFGs) written by high-frequency CO(2) laser pulses are investigated in detail. It is demonstrated that the resonant wavelength is dependent on the direction of the applied force and on the polarization state of the input light; however, the coupling strength is independent of these parameters. When a transverse load is applied along different orientations of the LPFG, the resonant wavelength may be shifted toward the longer wavelength, the shorter wavelength, or hardly shifted, whereas the absolute value of peak transmission attenuation is linearly decreased with an increase of the applied transverse load, with almost no sensitivity to the load direction. These unique transverse-load characteristics and the polarization dependence are due to the load-induced birefringence that leads to the rotation of optical principal axes in the LPFG.
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Affiliation(s)
- Yiping Wang
- Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
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Kakarantzas G, Leon-Saval SG, Birks TA, Russell PSJ. Low-loss deposition of solgel-derived silica films on tapered fibers. OPTICS LETTERS 2004; 29:694-696. [PMID: 15072361 DOI: 10.1364/ol.29.000694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Films of porous silica are deposited on the uniform waists of tapered fibers in minutes by a modified solgel dip coating method, inducing less than 0.2 dB of loss. The coated tapers are an ideal platform for realizing all-fiber devices that exploit evanescent-field interactions with the deposited porous film. As an example we demonstrate structural long-period gratings in which a periodic index variation in the film arises from the porosity variation produced by spatially varying exposure of the waist to a scanned CO2 laser beam. The long period grating is insensitive to temperature up to 800 degrees C.
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Affiliation(s)
- G Kakarantzas
- Optoelectronics Group, Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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Kakarantzas G, Birks TA, Russell PSJ. Structural long-period gratings in photonic crystal fibers. OPTICS LETTERS 2002; 27:1013-1015. [PMID: 18026349 DOI: 10.1364/ol.27.001013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report what is believed to be the first example of structural long-period gratings written in pure silica photonic crystal fibers (PCFs). The gratings are realized by periodic collapse of the holes of the PCF by heat treatment with a CO(2) laser. The resulting periodic hole-size perturbation produces core-to-cladding-mode conversion. These results can lead to a new family of structural all-fiber devices that use the unique properties of PCFs.
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Humbert G, Malki A. Electric-arc-induced gratings in non-hydrogenated fibres: fabrication and high-temperature characterizations. ACTA ACUST UNITED AC 2002. [DOI: 10.1088/1464-4258/4/2/313] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kakarantzas G, Dimmick TE, Birks TA, Le Roux R, Russell PS. Miniature all-fiber devices based on CO(2) laser microstructuring of tapered fibers. OPTICS LETTERS 2001; 26:1137-1139. [PMID: 18049541 DOI: 10.1364/ol.26.001137] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A focused carbon dioxide laser beam is used to microstructure fibers that have already been narrowed by conventional fiber tapering. We describe three new miniature devices made with this technique: a fused fiber microcoupler with an interaction length of 200 mum, a long-period grating made from a periodic chain of microtapers, and a new type of prolate whispering-gallery mode microcavity.
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von Bibra ML, Roberts A, Canning J. Fabrication of long-period fiber gratings by use of focused ion-beam irradiation. OPTICS LETTERS 2001; 26:765-767. [PMID: 18040443 DOI: 10.1364/ol.26.000765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Long-period gratings have been made in nonphotosensitive optical fibers by irradiation of the core of a fiber with a focused beam of high-energy protons. The irradiated fibers exhibit relatively low loss, even before thermal annealing, and possess strongly wavelength-dependent transmission. The absence of a mask provides the opportunity to tailor the grating to a desired profile, and a variety of grating profiles were explored. The profile most resembling a sinusoid was found to produce the cleanest transmission spectra.
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