Presentation series Photon Physics, UU April 9, 2009 Marlous Kamp Fiber Lasers Presentation series Photon Physics, UU April 9, 2009 Marlous Kamp

Contents Basics Research Conclusion Gain medium Energy level schemes Set-up Characteristics Research Applications Yb-lasers Recent research: PCF Yb-laser Conclusion Advantages

Impurity-doping: Er,Nd,Yb,Tm Gain medium Impurity-doping: Er,Nd,Yb,Tm History: Now: Nd-doped fiber Er-doped fiber Elias Snitzer (1964) Basics Research Conclude www.fiberoptics4sale.com

Energy Level Schemes Erbium i  Substrate important champion = BK-7 borosilicate Ytterbium Basics Research Conclude 3 or 4-level depending on wavelength

Set-up advantage: low loss Cladding modes 125 μm (diode) Basics Research Conclude advantage: low loss Cladding modes 125 μm

Characteristics Operating wavelength λ = 1.53 – 1.56 μm Gain bandwidth (FWHM) Δλ = 25 nm Transition probability Aul = 90/s Upper level lifetime τu = 8 ms Stim. em. cross section σul = 7 x 10-25 m2 Inversion density ΔNu = 2 x 1024 m-3 Small signal gain g0 = 1.35/m Typical length L ~ 12 m Single pass gain factor eσΔNL = 107 Saturation intensity Isat = 19 MW/m2 Output power Pth = 1mW to 1 kW (design) Threshold pump power Pth = 3-6 mW Basics Research Conclude

Applications … and for fun Long-distance communication Fiber-optic sensors Processing: welding, cutting, texturing Medical: surgery, endoscopy, eye lasering Basics Research Conclude … and for fun www.defensetech.org www.smart-oe.com www.laserphotonics.com

High power / Short pulse Yb-doped fiber @ 1050 nm High power 2001  100 W 2008  1000 W Ultra-short pulse Erbium  50 fs Ytterbium  5 fs Basics Research Conclude

Research high-power Yb-doped PCF @ 1150-1200 nm 225 μm Basics Research Conclude Shirakawa et al., Optics Express 17:2 (Jan. 2009)

Advantages 1) Better beam quality & stability Compared to bulk lasers: 1) Better beam quality & stability 2) Practical: lighter, compacter, reliable, no mirror alignment, can be cheap. 3) Unusual wavelengths 4) Customize to needs Various doping ions Various media Fiber geometry … and much more ! Basics Research Conclude POF = polymer fiber

Thanks for your attention! Questions?

Core Modes Multimode fiber (step index) (graded index) Single mode fiber 100/140 μm 9/125 μm