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

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

3. 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

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

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

6. 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 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

7. 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

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

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

10. 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

11. Thanks for your attention!
Questions?

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