Fibers for Raman Amplifiers
Lasers & Amplifiers Fibers
Overview
The IXF-PDF & IXF-PDF-PM fiber series are Phosphorous P-Doped fiber especially designed to achieve very high Raman gain at 1.48 micron for high-power pumping of Erbium doped fibers. P-Doped Fiber offers a Raman shifted gain that is three times higher than the germanium-doped fibers.
The main application is to produce high-power sources at 1240 and 1480 nm that can be used as pump lasers in O-band and C-band fiber amplifiers respectively. Indeed, laser diodes are limited to ~200mW of optical output power while Raman lasers can generate 1W. (For 1310 nm Raman fiber amplifiers, the Raman Fiber features very low loss, as it’s a good alternative to the 1480 nm laser diode sources that are limited to 100 to 200 mW output power compared to the 1 watt Raman laser alternative.)
IXF-PDF fibers are efficiently pumped by several 10s of watts Ytterbium PM Double-clad fiber laser with operating wavelength between 1040 to 1120 nm. See also Our FBG and Ytterbium PM product pages.
With Germanium Raman fibers, the necessity to get the third (1240nm) and the sixth Stokes (1480nm) strongly complicates the design by multiplying the number of internal cavities. When pumping the IXF-PDF-PM series with a high power Ytterbium 1060 nm laser, the 1240 and 1480 nm laser are obtained directly at the first and the second Stokes making the design simpler.
Due to the Raman scattering peak at 1320 cm-1, the IXF-PDF series P-doped fibers can also be used to generate signal band light centered at 1.5 µm via stimulated Raman scattering with a 1.3 µm pump light source. The Raman gain is related to the power transfer from the optical pump power to the optical power at signal wavelengths (Stokes wavelengths) and is strongly dependent to the effective Area, to the intrinsic fiber losses and to the Dopants concentrations.
The IXF-PDF series have been optimized to offer the best trade-off between a small effective area, a high level of Phosphorous P2O5 dopants in the core of the optical fiber and an optimized Numerical A to increase the overlap of the fundamental mode with the fiber core increasing also Raman amplification efficiency.
