Electrically tunable Brillouin fiber laser based on a metal coated single mode optical fiber 1 2 4 5 6 7 8 9 10 11 12 13 1 5 16 17 18 19 20 21 22 23 24 25 2 6 35 36 37 38 39 40 41 42 43 44 45 46 47 48[.]
RINP 554 No of Pages 2, Model 5G 11 February 2017 Results in Physics xxx (2017) xxx–xxx Contents lists available at ScienceDirect Results in Physics journal homepage: www.journals.elsevier.com/results-in-physics Microarticle Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber S.M Popov a, Y.K Chamorovski a, V.A Isaev a, P Mégret b, I.O Zolotovskii d, A.A Fotiadi b,c,d,⇑ 10 11 12 13 16 17 18 19 20 21 22 23 24 25 a Institute of Radio Engineering and Electronics (Fryazino Branch) Russian Academy of Science, Vvedenskogo Sq 1, 141190 Fryazino, Moscow Region, Russian Federation Electromagnetism and Telecommunication Department, University of Mons, 31 Boulvard Dolez, Mons 7000, Belgium c Ioffe Physico-Technical Institute of the Russian Academy of Sciences, 26 Polytekhnicheskaya Street, St Petersburg 194021, Russian Federation d Ulyanovsk State University, 42 Leo Tolstoy Street, Ulyanovsk 432970, Russian Federation b a r t i c l e i n f o Article history: Received 21 December 2016 Accepted 23 January 2017 Available online xxxx Keywords: Brillouin fiber laser Metal-coated optical fiber Laser tuning Fiber sensors a b s t r a c t We explore tunability of the Brillouin fiber laser employing Joule heating For this purpose, 10-m-length of a metal-coated single-mode optical cavity fiber has been directly included into an electrical circuit, like a conductor wire With the current up to 3.5 A the laser tuning is demonstrated over a spectrum range of 400 MHz The observed laser line broadening up to 2 MHz is explained by frequency drift and mode-hoping in the laser caused by thermal noise Ó 2017 The Authors Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Single longitudinal-mode fiber lasers with a narrow linewidth are demanded for many potential applications in coherent optical communications, distributed sensing and microwave photonics Stimulated Brillouin scattering is a well-known universal way to organize narrow-band lasing in fiber configurations enabling a variety of the performance characteristics [1–5] Single-mode Brillouin fiber lasers based on a short fiber ring cavity exhibit low threshold, high spectral purity and low intensity noise [1–4] In this paper, we present a tunable Brillouin fiber laser pumped by a frequency-stabilized laser diode Controlling the temperature of the fiber through Joule heating, the Brillouin frequency shift can be changed by current The lasing frequency follows the Brillouin frequency shift change and, thus, can be tuned The experimental configuration of the laser is shown in Fig 1a The 1550 nm light from a 100 kHz linewidth laser diode is amplified up to the power of 150 mW by an erbium-doped fiber amplifier The amplified light is injected into the Brillouin laser cavity through a circulator to operate as the Brillouin pump The cavity comprises an optical circulator and 10-m-length of the metalcoated single-mode optical fiber [6] Lasing occurs in the cavity when the injected power exceeds the threshold (90 mW) The residual pump and laser light come out from the 5% ends (Out and 2, respectively) of a 95/5 coupler and could be combined in ⇑ Corresponding author at: Electromagnetism and Telecommunication Department, University of Mons, 31 Boulvard Dolez, Mons 7000, Belgium E-mail address: andrei.fotiadi@umons.ac.be (A.A Fotiadi) the 50/50 coupler for monitoring of laser spectrum by 20-GHz radio-frequency spectrum analyzer A polarization controller provides adjustment of the light polarization state inside the cavity Due to the circulator directionality, the pump light passes through the cavity with only one round trip and does not resonate in the cavity The Stokes light circulates in the cavity and gets the resonance for efficient lasing To tune the lasing frequency, the metal-coated single-mode fiber (SMF) is included directly into a Joule electrical circuit for heating employing the fiber copper coating as a conductor wire (the fiber coils are electrically isolated) Due to heating, the Brillouin gain spectrum is shifted leading to a change of the laser frequency The fiber used in the experiment has been manufactured in IRE (step-index difference 0.005, core/cladding diameters 9/200 lm, thickness of the copper coating 21.5 lm) and tested for operation at temperatures up to 900 °C Before the experiment, we have measured the Brillouin frequency shift (Fig 1b) in the fiber with BOTDA (OZ-optics, Inc.) At 20 °C it is 10,802 MHz GHz and exhibits a linear increase with the temperature demonstrating a slope of 1.3 MHz/°C that is slightly higher than for SMF-28 Corning fiber Fig shows the features of laser operation The Brillouin lasing threshold is achieved at pump power of 100 mW At the pump power of 150 mW the output power is 20 mW At this pump level the laser could be stabilized for operation with a linewidth 10%) in the cavity Fig 2b shows the results of the laser frequency tuning The frequency changes are not linear with the current: the curve demonstrates slope of 45 MHz/A and 135 MHz/A at low and high current, respectively The total laser frequency shift 400 MHz is achieved at the current of 3.5 A According to Fig 1b, the temperature of the fiber in this regime is 350 °C In conclusion, we have demonstrated an electrically tunable Brillouin fiber laser With control of the current flowing through the fiber, the lasing frequency can be tuned up to 400 MHz Over the whole tuning spectrum range the laser is able to operate with the linewidth of 2 MHz Further improvements of the laser performance require precise thermal stabilization of the laser cavity that is rather difficult technically for the considered configuration However, even with the reported features, the laser could be a simple, compact, and cost effective solution for many practical applications 112 Acknowledgement 114 The authors thank IRE staff for manufacturing of the metal-coated fiber The work was supported by IAP program VII/35 of the Belgian Science Policy, Ministry of Education and Science of Russian Federation (14.Z50.31.0015) and Russian Fund of Fundamental Research (16-32-60109 mol_a_dk, 14-29-08195, and 16-42732135 R-OFIM) 115 References 121 [1] Wu Zh, Zhan L, Shen Q, Liu J, Hu X, Xiao P Ultrafine optical-frequency tunable Brillouin fiber laser based on fiber strain Opt Lett 2011;36:3837 [2] Spirin VV, Mégret P, Fotiadi AA Passively stabilized doubly-resonant Brillouin fiber lasers In: Paul MCh, editor Fiber laser INTECH; 2016 [3] Spirin VV, López-Mercado CA, Kinet D, Mégret P, Zolotovskiy IO, Fotiadi AA A single-longitudinal-mode Brillouin fiber laser passively stabilized at the pump resonance frequency with a dynamic population inversion grating Laser Phys Lett 2013;10:015102 [4] Spirin VV, Kellerman J, Swart PL, Fotiadi AA Intensity noise in SBS with injection locking generation of Stokes seed signal Opt Exp 2006;14(18):8328–35 [5] Grukh DA, Kurkov AS, Razdobreev IM, Fotiadi AA Self-Q-switched ytterbiumdoped cladding-pumped fibre laser Quant Electron 2002;32(11):1017 [6] Popov SM, Voloshin VV, Vorobyov IL, Ivanov GA, Kolosovskii AO, Isaev VA, Chamorovskii YK Optical loss of metal coated optical fibers at temperatures up to 800 °C Opt Memory Neural Networks 2012;21:45–51 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 Please cite this article in press as: Popov SM et al Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber Results Phys (2017), http://dx.doi.org/10.1016/j.rinp.2017.01.034 113 116 117 118 119 120 137 ... be a simple, compact, and cost effective solution for many practical applications 112 Acknowledgement 114 The authors thank IRE staff for manufacturing of the metal- coated fiber The work was... Zolotovskiy IO, Fotiadi AA A single- longitudinal -mode Brillouin fiber laser passively stabilized at the pump resonance frequency with a dynamic population inversion grating Laser Phys Lett 2013;10:015102... Fotiadi AA Passively stabilized doubly-resonant Brillouin fiber lasers In: Paul MCh, editor Fiber laser INTECH; 2016 [3] Spirin VV, López-Mercado CA, Kinet D, Mégret P, Zolotovskiy IO, Fotiadi AA