Abstract
We demonstrate Raman oscillation at a wavelength of 1158 nm using a new vibrational mode in a phosphosilicate-glass system when pumped at a 1060-nm wavelength. The lower energy P-O vibration located at 640 cm-1 associated with pure phosphate glass system is comparatively weaker and is shifted to higher energy at 800 cm-1 in the phosphosilicate binary glass. Despite the relative weakness of this vibrational mode, we obtained an efficient Raman fiber laser with the use of fiber Bragg gratings used to select laser oscillation using this mode. The measured slope efficiency with respect to the launched pump power was 60.4% and a maximum laser power of 1.8 W was produced.
Highlights
Stimulated Raman scattering is an efficient nonlinearity in germanosilicate or phosphosilicate glass optical fibre and can be used to effectively generate downshifted wavelengths
We demonstrate Raman oscillation at a wavelength of 1158 nm using a new vibrational mode in a phosphosilicate-glass system when pumped at a 1060-nm wavelength
We show that in the binary phosphosilicate glass system, in contrast to the pure phosphate glass system, the lower energy P-O vibration is comparatively weaker and is shifted to higher energy
Summary
Stimulated Raman scattering is an efficient nonlinearity in germanosilicate or phosphosilicate glass optical fibre and can be used to effectively generate downshifted wavelengths. The phosphosilicate glass system is generally used to construct fibres for Raman fibre lasers (RFL’s) [1,2,3,4] because of the large Stokes shift, which scatters an incident photon to lower energy by 1330 cm-1 [5,6,7]. One way of achieving this end is to utilize the lower energy P-O vibration relevant to phosphate glass in a RFL arrangement comprising of a single Stokes shift. Other Stokes emissions, related to the Si-O vibration (at 420 cm-1 and 490 cm-1) have been been generated simultaneously in a Raman fibre laser arrangement
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