Optical Fiber Behavior in Radioactive Environments

IEEE ICC meeting, 31-10-06, St-Peterburg 1 Draka Comteq Optical Fibre Optical Fiber Behavior in Radioactive Environments Gerard Kuyt, Draka Comteq, Netherlands Elise Regnier, Draka Comteq, France Rob Gilberti, Draka Comteq, USA

Introductio Compared to copper cables, fiber optic systems have many advantages: - electromagnetic immunity no cross talk between adjacent fibers direct contact with high voltage electrical equipment and power lines / no ground loops of any kind - chemical stability impervious to corrosion / buried directly in most kinds of soil or exposed to corrosive atmospheres - low weight, low volume Communications through optical fibers much smaller than a wire / coaxial cable with similar information carrying capacity easier to handle and install, and uses less duct space - low attenuation, large bandwidth much higher data rates / ability to carry much more information and deliver it with greater fidelity than either copper wire or coaxial cable - ideal for secure and safe communication systems very difficult to tap but very easy to monitor / no possibility of a spark from a broken fiber. even in the most explosive atmospheres, there is no fire hazard IEEE ICC meeting, 31-10-06, St-Peterburg 2

IEEE ICC meeting, 31-10-06, St-Peterburg 3 Introductio Communications through optical fibers Improvement of fiber properties over the last decades - attenuation reduction presently: <0.2dB/km @1550nm - strong increase of information-transmitting capacity, - good mechanical resistance lifetime > 25y; mainly mankind failures - telecom development large fiber production volumes stabilization of fiber features, standardizations, background (20 years of experience). - radiation-resistance improvement: see rest of the presentation.

IEEE ICC meeting, 31-10-06, St-Peterburg 4 Conten I- Optical fibers used in radiative environments 1. Optical fiber applications in radioactive environments 2. Response of optical fiber exposed to radiations: state of the art 3. Improvement of fiber radiation-resistance over the last 25 years 4. Who currently uses optical fibers in radioactive environments? II- Commercial RadHard fibers 1. RadHard Single Mode Fibers 2. RadHard Multi Mode Fibers

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 5 adiative environment: Nature of radiation Total dose (remind: 1Gy = 100 Rad) Dose-rate emark: some applications can have low oses but high dose-rates (ex: LMJ). Particles Electromagnetic rays Typical Ionizing doses rays and dose-rates for different radioactive environments (by S. Girard) Cosmic rays Neutrons (fission) α and β rays γ rays X rays UV rays Non-ionizing rays Radio waves Micro waves Infrared rays Visible light

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 6 Doses Dose-rates Typical applications ilitary* protection of strategic ivil data From a few mgy up to 10 2-10 3 Gy From 10 Gy/h up to 10 9 10 13 Gy/h (pulsed irradiations) Data transfer pace From 10 up to 10 4 Gy From 10-2 up to 10 2 Gy/h Data transfer, gyroscopes uclear power Normal lants 40 C Accident 120 C igh Energy Physics boratories (CERN-LHC) ~5.10 5 Gy (over 40 years) ~ 10 6 Gy < 10 5 Gy (annual total dose) Up to 10 6 Gy (future equipments) ~1 Gy/h ~10 3 Gy/h < 1 Gy/h Up to 10 Gy/h Tele-operation (up to 10 5 Gy/h), data transfer, fiber sensors Data transfer, fiber sensors o official data Irradiative environments (= critical domains) Safety and reliability!! Very important to well know the behavior of optical fibers under radiations.

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 7 Behavior silica fibers in radiative environments: state of the art Many studies on this topic for 25 years quite a good knowledge ain critical point: attenuation increase (Radiation-Induced Attenuation or RIA) See next slide ther potential changes in fiber properties Mechanical properties no effect observed up to 10 MGy (SCK-CEN coll.). [Van Uffelen] Today, we are aware that it is very important to choose the most appropriate iber (the nature of which depends on the application), clearly define the acceptable loss udget (including the whole optic system) and the irradiation conditions. Preliminary γ-radiation tests give an idea of fiber radiation-resistance.

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 8 Behavior silica fibers in radiative environments: state of the art nder radiation, fiber attenuation increase depends on radiation conditions: total dose, dose-rate, temperature, injected power, etc Dose-rate dependency: Induced Loss [db/km] 100 10 1 0.1 3.7 Gy/s 1.6 Gy/s 0.22 Gy/s 0.02 Gy/s 13000 Gy/h 70 Gy/h 5400Gy/h 800 Gy/h RIA strongly decreases with decreasing doserate! 0.1 1 10 100 1000 10000 100000 Dose [Gy(SiO 2 )] Example of dose-rate dependency of RIA for a fiber of Pure Silica type (extracted from Kuhnhenn s presentation - 2005, on CERN website: http://indico.cern.ch/conferencedisplay.py?confid=a056455). Extracted from Kyoto 1992.

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 9 Behavior silica fibers in radiative environments: state of the art nder radiation, fiber attenuation increase depends on radiation conditions: total dose, dose-rate, temperature, injected power, etc Temperature dependency RIA decreases with increasing temperature Annealing after radiation -17 C 21 C Example of temperature dependency of Radiation- Induced Attenuation (RIA) for MMF fibers (extracted from S. Theriault s Photonics North 2006, Quebec). Example of RIA annealing for MMF fibers

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 10 Behavior silica fibers in radiative environments: state of the art he Radiation-Induced Attenuation (RIA) strongly varies from a fiber to another. o the attenuation level after the radiation exposure, and both dose-rate and perature dependencies strongly vary. RIA dependency with injected power or Photobleaching 1µW RIA decreases with increasing the injected power 7mW Example of RIA dependency with injected power (photobleaching) (extracted from S. Theriault s Photonics North 2006, Quebec).

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 11 Behavior silica fibers in radiative environments: state of the art he Radiation-Induced Attenuation (RIA) strongly varies from a fiber to another. o the attenuation level after the radiation exposure, and both dose-rate and perature dependencies strongly vary. Impact of fiber composition at low doses and at high doses Ge-doped fibers (SMFs) No annealing when P is present either in the core or in the clad PSCF A measured @1550nm for 4 fibers gamma-irradiated in the same conditions (up to a total dose of 150Gy, 0.1Gy/s) (extracted from Girard s PhD report - 2003) RIA measured @1310nm for 2 Ge-doped SMFs and one PSCF gamma-irradiated in the same conditions (up to 3.6MGy, at 3kGy/h) (extracted from Van Uffelen s PhD report - 2001)

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 12 Behavior silica fibers in radiative environments: state of the art he Radiation-Induced Attenuation (RIA) strongly varies from a fiber to another. o the attenuation level after the radiation exposure, and both dose-rate and perature dependencies strongly vary + different spectral shape. Impact of fiber composition on RIA spectral shape 10000 Temperature dependency RIA [a.u.] 1000 100 10 P-doped SMF (5Gy) Ge-doped fibers are more sensitive to temperature 1 PSCF (100Gy) 0.1 Ge-doped SMF (100Gy) 400 900 1400 1900 Wavelength [nm] RIA spectra measured after annealing for 3 fibers with different core compositions (extracted from Regnier et al RADECS 2006, Athens) Temperature dependence of RIA at 1300nm due to a γ-irradiation for 0.4hrs at 10 4 Gy/h (Extracted from Kanamori 1986).

Fiber use in radiative environment adiation-induced Attenuation or RIA What we have learnt for 25 years mpact of dopants: P, Ge, F, B [Griscom, Friebele, Henschel, Van Uffelen, Berghmans, Kuhnhenn, Girard, Ott, Tortech] Do not use P and B as dopants (=> be wary of MCVD process!) Formation of Phosphorus-defects (P1, P2, P4 and POHC) that have strong absorption bands; one of them (P1-band) is located in the NIR => very bad for uses at 1310nm and 1550nm (i.e. std telecom λ). Remark: B can be used for pulsed irradiations (B improves the transient response at the expense of the permanent attenuation) At very high doses (~MGy), use pure silica core fibers instead of Ge-doped fibers 3.5MG Ge-doped fibers: formation of Ge-defects (GeE, Ge(1), Ge(2), GEC) Ge-doped SMFs PSCF: formation of silica defects (NBOHC, POR, SiE, STH), PSCF have smaller RIA at high doses, + lower sensitivity to T PSCF IEEE ICC meeting, 31-10-06, St-Peterburg 13 (extracted from Van Uffelen s PhD report - 20

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 14 What we have learnt for 25 years adiation-induced Attenuation or RIA Impact of manufacturing conditions: coating, residual impurities, T f, OH and Cl contents [Deparis, Semjonov, Barnes, Henschel, Iino, Hanafusa, Griscom, Yamaguchi, Ott, etc.] Coating: can be critical at high doses, Polyimide, acrylate, hermetic coating Radiation can cause crosslinking resulting in microbending. Residual impurities: usually should be as low as possible, Alcaline, metallic impurities. T f (fictive temperature): should be reduced, Minimizing the fictive temperature of the glass allows to minimize the number of defects. OH and Cl content: depends on operating wavelength. First well define your operating conditions.

Fiber use in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 15 What we have learnt for 25 years adiation-induced Attenuation or RIA Impact of radiation conditions: dose-rate, total dose, temperature, nature of radiation [Van Uffelen, Kyoto, Griscom, Henschel, West] RIA generally increases with increasing dose and dose-rate, but decreasing temperature. Take care of comparing only RIA curves that have been obtained exactly in the same conditions! Be aware that accelerated gamma-exposures (i.e. at higher dose-rates than the final operating dose rate) will lead to much higher RIA. However, such trials can be very useful for fiber comparison. Try to make the preliminary radiation-tests with conditions as similar as possible to the final in-situ radiation conditions. Nature of radiation (gamma, neutron, X, etc.) => seem to lead to quite comparable results (for same doses). Note that 60 Co sources are the easiest to use. Many radiation facilities (Fraunhofer Institute, INO, Tecnologica, CEA)

Fiber uses in radiative environment IEEE ICC meeting, 31-10-06, St-Peterburg 16 Today s use of optical fibers in radiative environments Who currently uses optical fiber in radiative environments? - Military no official data; certifications (USA: MIL-PRF 49291) - Nuclear Power Plants - High Energy Physics Laboratories CERN (Geneva); Fermi National Accelerator Lab. ( USA) - Space industry NASA / ESA

IEEE ICC meeting, 31-10-06, St-Peterburg 17 Conten I- Optical fibers used in radiative environments 1. Optical fiber applications in radioactive environments 2. Response of optical fiber exposed to radiations: state of the art 3. Improvement of fiber radiation-resistance over the last 25 years 4. Who currently uses optical fibers in radioactive environments? II- Commercial RadHard fibers 1. RadHard Single Mode Fibers 2. RadHard Multi Mode Fibers

IEEE ICC meeting, 31-10-06, St-Peterburg 18 Commercial RadHard fiber What kind of fiber to choose? Single mode fibers (SMF) * High data rates over long distances: Current RadHard: SMF G.652 (MIL qualified: MIL - PRF- 49291/7) Future RadHard: Super RadHard SMF (in development)

IEEE ICC meeting, 31-10-06, St-Peterburg 19 Commercial RadHard SM RadHard SMF behavior omparison of different commercial SMFs tested for CERN project by FI 40 10 X Fujikura Heraeus Draka 445755 Draka New Y Corning 35 30 X Fujikura Heraeus Draka 445755 Draka New Y Corning Induced Loss [db/km] 1 Induced Loss [db/km] 25 20 15 10 λ=1310 nm, D=10 4 Gy, D=0.225 Gy/s, T=28 C, l=100 m, P=10/40 µw 1 10 100 1000 10000 Dose [Gy(SiO 2 )] 5 0 λ=1310 nm, D=10 4 Gy, D=0.225 Gy/s, T=28 C, l=100 m, P=10/40 µw 0 2000 4000 6000 8000 10000 Dose [Gy(SiO 2 )] Radiation-Induced Attenuation for different commercial SMFs by Fraunhofer Insitute (extracted from Kuhnhenn s presentation - 2005, CERN website: http://indico.cern.ch/conferencedisplay.py?confid=a056455).

Commercial RadHard fiber What kind of fiber to choose? Single mode fibers (SMF) * High data rates over long distances: Current RadHard: SMF G.652 (MIL qualified: MIL - PRF- 49291/7) Future RadHard: Super RadHard SMF (in development) Multimode fibers (MMF) * * Short distance / Datacom Current: 50 µm RadHard (MIL qualified: MIL - PRF - 49291/1) Current: 50 µm OM3 (10Gb/s over 300m @850nm) RadHard Current: 62.5 µm RadHard (MIL qualified: MIL - PRF - 49291/6) * ) Recommended for Nuclear Power Plants IEEE ICC meeting, 31-10-06, St-Peterburg 20

Commercial RadHard MM RadHard 50 µm MMF behavior omparison of different commercial MMFs tested for ESA by INO Radiation-induced attenuation in some COTS fiber samples (100 metres) Average dose rate = 157 Gy/h, Total dose = 1000 Gy Radiation-induced attenuation [db] 12 11 10 9 8 7 6 5 4 3 2 1 0 Draka MaxCap 300 Radhard optimized Draka MaxCap 300 Standard Draka MaxCap 300 Radhard INO 712A1 Telecom Standard Telecom Radhard 0 200 400 600 800 1000 1200 Accumulated dose [Gy] fiber is not irradiated in this area, time of recovery = 60 minutes raka-maxcap 300 RadHard optimized: recommended for space appl. [Theriault 2006] ériault, INO, Canada - 2006]: Radiation Effects on COTS Laser-Optimized Multimode Fibers Exposed to an Intense Gamma Radiation ld, by S. Thériault, Conference Photonics North IEEE 2006 ICC meeting, Quebec city, 31-10-06, June 2006 St-Peterburg 21

IEEE ICC meeting, 31-10-06, St-Peterburg 22 Commercial RadHard MM Example of RadHard 62,5 µm MMF under radiation 1310 nm, 1,67 Gy/s, 6µW, 28 C Radiation-Induced Attenuation [db/km] 80 60 40 20 0 0 2000 4000 6000 8000 10000 Total dose [Gy] Measurements performed at Fraunhofer Institute Germany, by J. Kuhnhenn - 2005 Approval: MIL - PRF - 49291/6

IEEE ICC meeting, 31-10-06, St-Peterburg 23 Summary - Conclusion Optical fiber (cable) offers important features in Tele- and Datacom, also in radiative environments The behavior of optical fiber in radiative environments can be quite complex Careful characterization of the radiation conditions is important Careful selection of fiber is very important, based on the allowed loss budget Dedicated support from manufacturer experts is significant For Nuclear Power Plants the RadHard MMF fibre is available, including OM3 (10Gb/s) fibre Draka Comteq offers a range of MIL-spec approved RadHard fibres

IEEE ICC meeting, 31-10-06, St-Peterburg 24 Thank you for your kind attention! Any questions? Contact: gerard.kuyt@draka.com