Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser

Transcription

1 Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser Urs Pedrazza 1,2, Valerio Romano 2, Willy Lüthy 2, Christian Ban 1, Julien Sauvet 1, Florian Dürr 1, Hans G. Limberger 1, René P. Salathé 1, Thomas Feurer 2 1 Laboratoire d'optique appliquée, Ecole polytechnique fédérale de Lausanne, Switzerland 2 Institute of Applied Physics, University of Bern, Switzerland

2 Outline Yb-doped Al-codoped Sol-Sel Silica Glass Fiber Laser Motivation Production Optical Characterization Mechanical Characterization

3 Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser Motivation Sol-Gel Technique Ytterbium Production Optical Characterization Mechanical Characterization

4 Sol-Gel Technique Flexibility for photonic research purposes... Flexibility of the products (thin films, powders, bulk) Flexibility of dopant content any water or ethanol soluble dopant can be dissolved homogeneously Flexibility of covering any shape by wetting the surfaces multi-core fibers, microstructures fibers (photonic crystals) Flexibility of choosing processing temperatures (200 C 2000 C) Very cost-effective Starting summer 2002 building to tower Ytterbium fiber laser

5 Ytterbium Yb ¾ High quantum efficiency No cross-relaxation No excited state absorption No up-conversion ¾ ¾ ¾ Absorption fits InGaAs diodes Broad emission band - short pulses Tunability (re-absorption) Rare-Earth-Doped Fiber Lasers and Amplifiers, M.J.F. Digonnet, Editor (Marcel Dekker Inc., New York 2001)

6 Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser Motivation Production Sol-Gel Route Reduction of OH - -Group Content Optical Characterization Mechanical Characterization

7 Production by the Sol-Gel Route Wet chemistry process hydrolysis and polycondensation H 3 C CH 3 Si-OR + H 2 O Si-OH + ROH Si-OH + HO-Si Si-O-Si + H 2 O O O Si O O H 3 C CH 3 Wetting of surface, evaporation xerogel Thermal post-treatment (densification, reduction of OH - -groups)

8 Reduction of OH - - Group Content He, O 2 Oven Tube Collapsing Drawing Lathe Yb 1 :Al 10 :(SiO 2 ) 89 High viscosity 2.7 µm each layer, total 3 layers Vitrification layer-by-layer 1800 C OH Wavenumber Wellenzahl [cm [cm -1 ] -1 ] Transmission (bel. [%] Einh.) IR Spectra OH - Quartz (for comparison) 950 C 500 C 250 C SiO B. Wilhelm, IAP

9 Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser Motivation Production Optical Characterization Monomode-Fiber Laser Spectral Characteristics Laser Performance Mechanical Characterization

10 Monomode-Fiber Laser Difference index of refraction between core and cladding: Numerical aperture: Diameter fiber 140 µm Diameter core 6.3 µm Lifetime 764 ± 4 µs (20 cm, 908 nm) Losses 0.53 dbm nm Losses < 0.1 dbm laser wavelengths IT ultra low OH dbkm -1 (0.8 dbkm -1 ) IT high OH dbkm -1

11 Spectral Characteristics 1037 nm (20 cm) saturation nm (65 cm)

12 Laser Performance 5 P out (mw) nd band 2 nd line starting 1080 nm 1088 nm 65 cm long fiber 64 % slope eff P in (mw)

13 Ytterbium-doped Aluminum-codoped Sol-Sel Silica Glass Fiber Laser Motivation Production Optical Characterization Mechanical Characterization Tomographic Measurements

14 Tomographic measurements 3.0 core axial stress [kg/mm2] Yb 1 at.-% Al 10 at.-% Ge 9 at.-% radial position [um]

15 Thank you for your attention! Acknowledgements: Markus Pollnau, University of Twente, NL