State-of-the-art diffraction-limited fiber lasers are presently capable of producing kilowatts of power. Power levels
produced by single elements are gradually increasing but beam combining techniques are attractive for rapidly scaling
fiber laser systems to much higher power levels. We discuss both coherent and spectral beam combining techniques for
scaling fiber laser systems to high brightness and high power. Recent results demonstrating beam combination of 500-W
commercial fiber laser amplifiers will be presented.
Slab-coupled optical waveguide lasers (SCOWLs) and amplifiers (SCOWAs) are inherently low-confinement structures
with large nearly-circular modes that are easily coupled to optical fibers or collimated for free-space applications.
Recently SCOWL powers have increased to 3 W by increasing the cavity length to 1 cm and improving the heat
removal. SCOWAs are coherently combined using active phase control to achieve a very high-brightness source. Our
coherent beam combining system consists of single-pass amplifiers with angled-facet SCOWAs that suppress feedback.
Single-pass, 5-mm long, SCOWAs have now been demonstrated with 1.5 W CW output with only 50 mW seed power.
Arrays of 47 SCOWAs have demonstrated a raw power of 57 W with 50 mW of seed power per element. A coherent
beam combining demonstration is currently being assembled.