Wide-passband, temperature-insensitive, and compact π-phase-shifted long-period gratings in endlessly single-mode photonic crystal fiber

Zhu, Yinian; Shum, Ping; Bay, Hui-Wen; Chen, Xiaoyan; Tan, Chung How; Lu, Chao

doi:10.1364/ol.29.002608

Cited by 14 publications

(9 citation statements)

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“…Compared with the temperature sensitivity, e.g., 58 pm/°C, of other CO 2 -laser-induced LPFGs in conventional single-mode fiber, 4,7 the resonant wavelength of the CO 2 -laser-notched LPFGs on the PCF is insensitive to temperature, which is due to the airhole structure of the pure silica PCF. 10 Thus our infiber polarizer resolves the temperature sensitivity problem of other in-fiber polarizers fabricated in the conventional single-mode fiber.…”

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confidence: 83%

In-fiber polarizer based on a long-period fiber grating written on photonic crystal fiber

et al. 2007

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A novel in-fiber polarizer based on a long-period fiber grating (LPFG) is written by using a focused CO 2 laser beam to notch a photonic crystal fiber periodically. Such a polarizer exhibits a high polarization extinction ratio of more than 20 dB over a wide wavelength range of ϳ11 nm near 1550 nm and a very low temperature sensitivity of 3.9 pm/°C, which overcomes the disadvantages of the temperature sensitivity of other in-fiber polarizers created on conventional single-mode fiber. © 2007 Optical Society of America OCIS codes: 050.2770, 060.2340, 060.4510, 060.2420 Polarizers and other polarization-related devices are very important in the field of optical fiber communications and sensors. Compared with bulk waveguide polarizers, in-fiber polarizers are desirable devices in all-fiber communication systems because of their low insertion loss and compatibility with optical fiber. Optical fiber polarizers are usually made by polishing the fiber laterally and coating a birefringence crystal 1 or a metal film 2 on the exposed guiding region. Zhou et al.3 reported a 45°C tilted in-fiber polarizer based on fiber Bragg gratings (FBGs). However, the high temperature sensitivity of the polarizer created in conventional single-mode fiber is a disadvantage for its application in optical fiber communications. Clear polarization dependence has been observed in CO 2 -laser-induced long-period fiber gratings (LPFGs) due to their asymmetric refractive index profile within the cross section of these gratings.4-6 Some of us recently reported a novel LPFG fabrication technique based on using a focused CO 2 laser beam to notch a conventional single-mode fiber periodically. 7Such a technique can write high-quality LPFGs with a low insertion loss and high polarization-dependent loss (PDL).In this Letter we present an in-fiber polarizer based on the LPFG fabricated by use of a focused CO 2 laser beam to notch a photonic crystal fiber (PCF) periodically. This LPFG polarizer exhibits a high polarization extinction ratio of more than 20 dB over a wide wavelength range of ϳ11 nm and a low temperature sensitivity of 3.9 pm/°C. An experimental setup, as shown in Fig. 1 of Ref. 7, was employed to write LPFGs by use of the focused CO 2 laser beam to notch the PCF periodically. A large-mode-area (LMA-10) PCF from BlazePhotonics 8 was employed and situated on the focal plane of the CO 2 laser beam. The cross section of the PCF with a cladding diameter of 124± 1 m and a core diameter of 11± 1 m is illustrated in Fig. 1(a). Following the LPFG fabrication process reported in Ref. 7, the focused CO 2 laser beam scanned repeatedly and periodically at the location corresponding to each grating period of the PCF via a twodimensional optical scanner under computer control. Focused high-frequency CO 2 laser pulses with enough energy hit repeatedly the side of the PCF. Such repeated hitting induces a local high temperature in the fiber, which not only collapses air holes in the outer cladding of the PCF but actually ablates some of the glass from the ...

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confidence: 83%

In-fiber polarizer based on a long-period fiber grating written on photonic crystal fiber

et al. 2007

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“…[71][72][73][74][75] The grating writing efficiency can be enhanced with a fiber annealed at a sufficiently high temperature. 29,71,72 Compared with normal UV-laser exposure technique, the CO 2 laser irradiation technique is easily used to write special gratings such as phase-shifted LPFGs, 28,69 chirped LPFGs, 76 complicated apodized LPFGs, 77 grating pairs, 62 and ultralong period fiber gratings with a period of up to several millimeters. [78][79][80] LPFGs have also been successfully achieved with a CO 2 laser during the fiber-drawing process.…”

Section: A To Write Lpfgs In Conventional Glass Fibersmentioning

confidence: 99%

“…5-15 Since Hill et al 1 and Vengsarkar et al 5 wrote the first FBG and LPFG in conventional glass fibers in 1978 and 1996, respectively, the fabrications and applications of in-fiber gratings have achieved rapid developments. Various fabrication methods, such as ultraviolet ͑UV͒ laser exposure, 5-15 CO 2 laser irradiation, [16][17][18][19][20][21][22][23][24][25][26][27][28][29] electricarc discharge, [30][31][32][33][34][35][36][37] femtosecond laser exposure, [38][39][40][41][42][43] mechanical microbends, [44][45][46][47][48][49][50][51] etched corrugations, [52][53][54][55][56][57] and ion beam implantation, [58][59][60] have been demonstrated to write LPFGs in different types of optical fibers. Numerous LPFGbased devices have ...…”

Section: Introductionmentioning

confidence: 99%

“…Compared with the UV-laser exposure technique, the CO 2 laser irradiation technique is much more flexible and low cost because no photosensitivity and any other pretreated process are re-quired to write a grating in the glass fibers. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] Moreover, the CO 2 laser irradiation process can be controlled to generate complicated grating profiles via the well-known point-topoint technique without any expensive masks. This technique could be, hence, used to write LPFGs in almost all types of fibers including pure-silica photonic crystal fibers ͑PCFs͒.…”

Section: Introductionmentioning

confidence: 99%

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Review of long period fiber gratings written by CO2 laser

Wang

2010

Journal of Applied Physics

220

134

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This paper presents a systematic review of long period fiber gratings (LPFGs) written by the CO2 laser irradiation technique. First, various fabrication techniques based on CO2 laser irradiations are demonstrated to write LPFGs in different types of optical fibers such as conventional glass fibers, solid-core photonic crystal fibers, and air-core photonic bandgap fibers. Second, possible mechanisms, e.g., residual stress relaxation, glass structure changes, and physical deformation, of refractive index modulations in the CO2-laser-induced LPFGs are analyzed. Third, asymmetrical mode coupling, resulting from single-side laser irradiation, is discussed to understand unique optical properties of the CO2-laser-induced LPFGs. Fourthly, several pretreament and post-treatment techniques are proposed to enhance the efficiency of grating fabrications. Fifthly, sensing applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based temperature, strain, bend, torsion, pressure, and biochemical sensors. Finally, communication applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based band-rejection filters, gain equalizers, polarizers, and couplers.

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“…The fabrication of LPGs in pure silica PCF was realized primarily by modification of glass structure as we previously demonstrated [7]. From mechanics point of view, any physical or geometrical deformation in a silica fiber causes its strength to become weak because there are the flaws or creaks created as stress intensifiers that finally fracture the fiber at low stress levels.…”

Section: Fabrication Of Lpgs In Esm-pcfmentioning

confidence: 99%

Strain-insensitive and high-temperature long-period gratings inscribed in photonic crystal fiber

Zhu

Shum

Bay

et al. 2005

OFC/NFOEC Technical Digest. Optical Fiber Communication Conference, 2005.

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Wide-passband, temperature-insensitive, and compact π-phase-shifted long-period gratings in endlessly single-mode photonic crystal fiber

Cited by 14 publications

References 14 publications

In-fiber polarizer based on a long-period fiber grating written on photonic crystal fiber

In-fiber polarizer based on a long-period fiber grating written on photonic crystal fiber

Review of long period fiber gratings written by CO2 laser

Strain-insensitive and high-temperature long-period gratings inscribed in photonic crystal fiber

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