Prototype CO_2 laser-induced long-period fiber grating variable optical attenuators and optical tunable filters

Braiwish, Mohammad I.; Bachim, Brent L.; Gaylord, Thomas K.

doi:10.1364/ao.43.001789

Cited by 37 publications

(17 citation statements)

References 15 publications

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“…In this investigation we are probably dealing with a larger fraction of energy deposited in the cladding, and hence we obtained a higher grating strength value ͑30 dB͒, which outperforms all the grating strength values for all other photochemical inscription techniques. At the same time it is similar to values obtained in experiments with such nonphotochemical recording methods as CO 2 laser irradiation 11 and the electric arc technique. 12 This result is not surprising, as both of these techniques involve energy deposition in the cladding.…”

supporting

confidence: 86%

Strong long-period fiber gratings recorded at 352?nm

et al. 2005

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We describe long-period grating inscription in hydrogenated telecom fibers by use of high-intensity femtosecond 352 nm laser pulses. We show that this technique allows us to fabricate high-quality 30 dB gratings of 300 m period and 2 cm length by use of a three-photon absorption mechanism. © Long-period fiber gratings (LPFGs, also known as transmission gratings) have existed since the mid-1990s. 1 They were originally fabricated photochemically by UV laser light at wavelengths coinciding with the maximum of the absorption band of defects in germanosilicate glass, and this is the most frequently used way of LPFG fabrication. For this purpose, KrF excimer laser radiation (248 nm; Ref. 2) or the second-harmonic radiation of a cw argon-ion laser (244 nm; Ref. 3) is usually used. Such a conventional low-intensity UV approach leads to a refractive-index change in the Ge-doped fiber core by means of single-quantum photochemical reactions. Recently we used high-intensity 264 nm femtosecond pulses (the fourth harmonic of our Nd:glass laser system 4 ) for recording LPFGs in single-mode telecom fibers. Under these experimental conditions, the inscription proceeds by means of a two-photon mechanism. 5In this report, we applied 352 nm radiation for LPFG inscription in the hydrogenated single-mode telecommunication fibers SMF-28 and SMF-28e. A schematic of the experimental setup is given in Fig. 1. For inscription of LPFGs we used the thirdharmonic radiation of a commercial femtosecond Nd-:glass laser (Twinkle; Light Conversion, Ltd., Lithuania), which was generated in a 2 mm long KDP crystal cut for type I interaction ( = 47.6°, = 45°). The method of frequency tripling was similar to that described in Ref. 6. The pulse duration of the resultant 352 nm pulses was 250 fs (FWHM), the beam diameter was 0.27 cm (FWHM), the repetition rate was 27 Hz, and the pulse energy was as much as 150 J. The femtosecond UV pulses were focused by a CaF 2 spherical lens, with a 48.6 cm focal distance, through a slit of width 150 m and onto a fiber (with the acrylate coating removed) that was placed behind the slit at a distance of ϳ100 m. The movement of the fiber and the control of the light's fluence were accomplished according to the method described in Ref. 5. For LPFG inscription we used the standard telecom fiber SMF-28 (supplied by Elliot Scientific) and the enhanced telecom fiber SMF-28e (supplied by Corning), both with a core diameter of 8.2 m, a cladding diameter of 125 m, and a numerical aperture of 0.14. The fibers were sensitized in a hydrogen atmosphere at 160 bars ͑120 kTorr͒ at 80°C for 90 h.Figures 2(a) and 2(b) present the experimental transmission loss spectra for two recorded gratings in SMF-28 and SMF-28e fibers, respectively. These gratings were fabricated with a 300 m period, and they were 2 cm in length.First we want to emphasize that our LPFGs, inscribed by high-intensity 352 nm pulses, are stronger than those produced by other photochemical methods. This statement refers to gratings of the same length and the sam...

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confidence: 86%

Strong long-period fiber gratings recorded at 352?nm

et al. 2005

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“…164 A similar tuning technique for a LPFGbased filter was proposed in Ref. 61, in which prototype devices capable of variable attenuation at a fixed wavelength, wavelength tuning at a constant attenuation, and combinations of these spectral characteristics were demonstrated in the CO 2 -laser-induced LPFGs.…”

Section: B Gain Equalizersmentioning

confidence: 99%

“…Typically, in most of LPFG fabrication setups employing a CO 2 laser, 16,17,27,61 as shown in Fig. 1, the fiber is periodically moved along its axis direction via a computercontrolled translation stage, and the CO 2 laser beam irradiates periodically the fiber through a shutter controlled by a same computer.…”

Section: A To Write Lpfgs In Conventional Glass Fibersmentioning

confidence: 99%

“…V. The focused high-frequency CO 2 laser pulses scanned periodically across the employed fiber along "X" direction and then shifted a grating pitch along "Y" direction, i.e., the fiber axis, to create next grating period by means of two-dimensional optical scanners under the computer control. Compared with typical point-to-point fabrication systems, 16,17,27,61 no exactly simultaneous controlling is required in such a system because the employed fiber is not periodically moved along the fiber axis. Such a system can write high-quality LPFGs with a nearly zero insertion loss.…”

Section: A To Write Lpfgs In Conventional Glass Fibersmentioning

confidence: 99%

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Review of long period fiber gratings written by CO2 laser

Wang

2010

Journal of Applied Physics

222

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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“…Recently, several technologies have been proposed for single fiber in-single fiber out VOAs that belong to the all-analog family of VOAs. Example VOA designs include the use of micromechanics, 1 micromirrors, 2,3 liquid crystals, 4-8 magneto-optics, 9 thin-film filters, 10 long period fiber gratings, 11 and acousto-optics. 12 Accurate high resolution operation of analog design VOAs requires closed loop operations of VOA with constant updated module calibration.…”

Section: Introductionmentioning

confidence: 99%

Super-resolution variable fiber optic attenuator instrument using digital micromirror device (DMD™)

Riza

Ghauri

2005

Review of Scientific Instruments

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Demonstrated is a super resolution, low loss, 100% repeatable and fast response digital variable fiber-optic attenuator instrument using a digital micromirror device. The attenuator design exploits beam expansion optics and a retroreflective architecture to achieve super-resolution with digital repeatability. The proof-of-concept attenuator at 1550nm demonstrates a 41.5dB optical attenuation range, optical insertion loss of 3.8dB, a 1ms maximum attenuation reset time, an optical polarization dependant loss of less than 0.07dB, and an optical resolution range of 2.9–0.0517mdB. The demonstrated attenuator is appropriate for fiber-optic test and instrumentation applications.

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Prototype CO_2 laser-induced long-period fiber grating variable optical attenuators and optical tunable filters

Cited by 37 publications

References 15 publications

Strong long-period fiber gratings recorded at 352?nm

Strong long-period fiber gratings recorded at 352?nm

Review of long period fiber gratings written by CO2 laser

Super-resolution variable fiber optic attenuator instrument using digital micromirror device (DMD™)

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