Erbiumdoped fiber amplifiers Joonas Leppnen Emma Kiljo Jussi
Erbium-doped fiber amplifiers Joonas Leppänen Emma Kiljo Jussi Taskinen Niklas Heikkilä Alexander Permogorov 21. 4. 2016 Photonics School of Electrical Engineering 21. 4. 2016 Group 3 EDFA
Content 1. 2. 3. 4. 5. 6. Introduction Theoretical Background Manufacturing Applications Current Trends and Future Perspectives Conclusions Photonics Group 3: EDFA 21. 4. 2016
Introduction • Invented in the 90's • The most important optical amplifiers in long-distance fiber communications, up to 800 km • Operates in wavelenghts of ca. 1. 5 µm • Coincidently the wavelength minimum of tradtitional optical fibers • Used to amplify the optical signal directly – No need for optical-electrical-optical conversions! Photonics Group 3: EDFA 21. 4. 2016
Theoretical Background • Signal input and laser diode output are multiplexed into fiber doped with trivalent erbium Er 3+ • Laser signal is used to pump the active media in order to amplify signal via stimulated emission at around 1. 55 µm for optical telecomms systems operating at C band • Glass compositions can affect the gain spectrum Image: RP Photonics, Encyclopedia of Laser Physics and Technology https: //www. rp-photonics. com/erbium_doped_fiber_amplifiers. html R. Paschotta, Photonics, Encyclopedia of Laser Physics and Technology. https: //www. rp-photonics. com/encyclopedia. html Photonics Group 3: EDFA 21. 4. 2016
Theoretical Background • Commonly via higher absorption cross-section, shorter lifetime upper state (less noise but more stabilized source required) or broader absorption band lower state transition (more noise but higher power efficiency) • Fibers often also doped with Ytterbium Yb 3+ at 980 nm for more effective transition by increasing pumping efficiency via larger absorption cross-section of Ytterbium around 980 nm • Higher concentration of Yb 3+ than Er 3+ is used [Honkanen 1997] S. Honkanen, High Er concentration phosphate glasses for planar waveguide amplifiers, Proc. SPIE 2996, Rare-Earth-Doped Devices, 32 , 1997 [Paschotta] R. Paschotta, Photonics, Encyclopedia of Laser Physics and Technology. https: //www. rp-photonics. com/encyclopedia. html. [Ron 2011] I. Ron, Neodymium, erbium, and ytterbium co-doped fiber amplifier, Opt. Eng, 2011 Photonics Group 3: EDFA 21. 4. 2016
Manufacturing Dopant chamber Fused Er-halide Cladding layer Vapour Phase Fabrication Methods • Core with Er dopant Low vapour pressure problem with Er-halides ~1000 °C Stationary burner Ø Variety of inside deposition (ID) Deposition tube 1. Dopant chamber – Some control of concentration by adj. temp. 2. Impregnation of silica sponge with Er -salt – Reproducible results for very low concentration – Uniform for long lengths 3. Introducing Al 2 Cl 6 causes incorporation of Al 2 O 3 deposition – Utilizes seed fiber inserted into center Heated lines Impregnated silica sponge Core with Er dopant + Al 2 O 3 Er-halide Porous boule Ø High quality outside vapor deposition (OVD) methods speculated – Organo metallic method on Nd Burner [Ainslie 1991] B. J. Ainslie, A review of the fabrication and properties of erbium-doped fibers for optical amplifiers, Journal of Lightwave Technology, 9(2), 220– 227, 1991 [Mori 1997] A. Mori, Erbium-doped tellurite glass fibre laser and amplifier, Electronics Letters, 33(10), 863, 1997 Photonics Group 3: EDFA 21. 4. 2016
Manufacturing Porous core Liquid Phase method 1. Deposition of porous core 2. Soaking the porous layer in Er salt solution Deposited cladding Burner Er solution 3. Drying the impregnated porous layer 4. Fusing the porous layer + collapsing into solid rod • Well known and simple Silica from deposit. tube Core • Difficult to maintain high concentration in the middle Ø Possibility to increase efficiency of pump power usage via composite core structures Deposited cladding [Ainslie 1991] B. J. Ainslie, A review of the fabrication and properties of erbium-doped fibers for optical amplifiers, Journal of Lightwave Technology, 9(2), 220– 227, 1991 [Mori 1997] A. Mori, Erbium-doped tellurite glass fibre laser and amplifier, Electronics Letters, 33(10), 863, 1997 Photonics Group 3: EDFA 21. 4. 2016
Applications • Splitting of same signal between lines • Used in Cable TV • Amplify input to give sufficient output to all branches Amplification before splitting Photonics Group 3: EDFA 21. 4. 2016
Applications • Maintain SNR • Smaller gain, but more frequent • Highly robust Amplification between long spans of fiber Photonics Group 3: EDFA 21. 4. 2016
Wideband EDFA ● ● ● Basic EDFAs have only 12 nm bandwidth, which can be doubled by adding gain equalization filters Combining separate amplifiers of different gain spectrum can yield a wider gain for the whole system Amplification rate is not affected by the data rate, which makes it easier to make upgrades to the system http: //www. olson-technology. com/mr_fiber/Wideband_EDFA. htm
Current Trends and Future Perspectives ● ● ● Gain higher power output Achieve accurate control over the bandwidth Tailor the Er doping and pump beam profiles to enhance effectiveness L. Bigot, "Few-Mode Erbium-Doped Fiber Amplifiers: A Review, " in Journal of Lightwave Technology, vol. 33, no. 3, pp. 588 -596, Feb. 1, 1 2015. Photonics Group 3: EDFA 21. 4. 2016
Thanks! Photonics Group 3: EDFA 21. 4. 2016
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