Colin Diehl & Jered Richter

High Power Double-Clad Fiber Laser

Single-Mode Fiber6 µm core / 125 µm cladding

+ High Beam Quality+ Low Propagation Loss- Lower Power Pumping- Expensive Pumping

Multimode Fiber50 µm core / 125 µm cladding

+ Higher Power Pumping+ Inexpensive Pumping- Poor Beam Quality- High Propagation Loss

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

Pump Laser – 50 W 915 nm Laser Diode

Protection Circuit

Erbium-Ytterbium Co-Doped Fiber

Optical Fiber Modes

Mode Scrambling

Experimental Results

• Maximum output power of 1.384 W

• Slope efficiencies increased 10% 13% 15%

Experimental Results

• Small changes due to inconsistent polish quality

• Coupling optimization not crucial

Linewidth

• Monochromator resolution of 0.3 nm

• FBG bandwidth of 0.1 nm

Beam Profile

•M2 = 1.10

•Rayleigh length = 3.3 mm

Beam waist = 86 µm

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