High Power Double-Clad Fiber Laser

1. High Power Double-Clad Fiber Laser Colin Diehl & Jered Richter

2. Single-Mode Fiber 6 µm core / 125 µm cladding High Beam Quality Low Propagation Loss Lower Power Pumping Expensive Pumping Multimode Fiber 50 µm core / 125 µm cladding Higher Power Pumping Inexpensive Pumping Poor Beam Quality High Propagation Loss

3. Double-Clad Fiber Laser light propagates in single-mode core Pump light propagates in inner cladding

4. Pump Laser – 50 W 915 nm Laser Diode

5. Protection Circuit

6. Erbium-Ytterbium Co-Doped Fiber

8. Optical Fiber Modes

9. Mode Scrambling

10. Experimental Results • Maximum output power of 1.384 W • Slope efficiencies increased 10%  13%  15%

11. Experimental Results • Small changes due to inconsistent polish quality • Coupling optimization not crucial

12. Linewidth • Monochromator resolution of 0.3 nm • FBG bandwidth of 0.1 nm

13. Beam Profile Beam waist = 86 µm • M2 = 1.10 • Rayleigh length = 3.3 mm

14. Future Improvements • Improve output power: • Increase EYDF length • Pump with 975 nm laser • Additional pump lasers • Improve linewidth • Incorporate Fabry-Perot cavity • Or incorporate diffraction grating