Hollow optical fibers and W-type fibers for high power sources and suppression of the stimulated Raman scattering
In this thesis, theoretical and experimental studies on hollow optical fibers (HOFs) and depressed clad hollow optical fibers (DCHOFs) for cladding-pumped high power fiber laser sources, operating at a wavelength range 900 - 1100 nm, are reported. In addition, the suppression of the stimulated Raman scattering (SRS) in a single-mode high power fiber-based master oscillator power amplifier (MOPA) source, using W-type Yb The suppression of the stimulated Raman scattering (SRS) in a small and single-mode core becomes an issue when considering the power scaling of a fiber laser. Here a W-type fiber was designed for SRS suppression with the fundamental mode cut-off set, by design, between the signal and the 1st order Raman Stokes wavelengths. SRS suppression was demonstrated in a high peak power fiber MOPA source with a single-mode output. The maximum peak power achieved was 13 kW with a small, and single-mode, core fiber without any evidence of SRS occurring.