To reduce the effects of stimulated Brillouin scattering (SBS) and photodarkening in silica-based fiber lasers (both factors can reduce achievable output power), the fiber core area can be increased or the fiber length can be decreased. However, large-core bend-sensitive fibers are difficult to handle, and decreased fiber lengths require difficult-to-achieve increased rare-earth-dopant concentrations. Researchers at Stanford University (Stanford, CA) and NP Photonics (Tucson, AZ) have overcome these issues by developing, to their knowledge, the first cladding-pumped continuous-wave ytterbium (Yb)-doped phosphate-glass fiber laser that has a higher photodarkening threshold than silica-based fiber lasers.
Although other Yb-doped phosphate-glass fiber lasers have been fabricated with wavelengths as long as 975 nm, none achieved output power levels above 3 W and none target power-scaling capability in the 1 μm region. In addition to achieving 19.6 W output power at a lasing wavelength of 1070 nm, the fiber laser was fabricated from specially designed phosphate fibers that are more easily doped than silica fibers and can be further optimized to improve pump absorption and increase output power levels. Contact Yin-Wen Lee at [email protected].