• Ji, J.
• Codemard, C. A.
• Nilsson, Johan
• Sahu, Jayanta Kumar

Abstract

In recent years, rare-earth doped silica fiber lasers have become a popular medium to generate very high-power laser source, in particular in the 1 µm range where up to 10 kW single-mode ytterbium doped fiber (YDF) laser source has been reported and up to 0.9 kW from Tm doped fiber. The powers from other wavelengths are much lower typically between 10 to 100 W. An alternative to produce gain and power in optical fiber is to use nonlinear effect such as stimulated Raman scattering (SRS). SRS is wavelength agile, limited only by the transparency range of the fiber and the pump power wavelength. In addition, SRS sources benefit from low quantum defect, in particular at shorter wavelengths making them extremely efficient. However, because these effects rely on strong optical intensities to take place, fibers with small core size are typically used with core pumping scheme, limiting the scope for power scaling. Therefore, no very high power Raman fiber laser (RFL) has been reported and little progress has been made to increase the output power of those. As far as we are aware, the highest reported power from a core pumped RFL is about 68 W. There are several challenges in power scaling core-pumped Raman fiber laser, mainly the power handling capacity of single-mode fiber and the careful adjustment of the fiber length to avoid spurious 2nd order Stokes generation in the laser cavity.

Topics

• impedance spectroscopy
• defect
• Ytterbium