The evolution of Stokes generation up to the n’th stage and the analytical solutions of commonly used Raman equations including numerical simulation and experimental results is reported. For the experimental work, a 1-km un-doped single-mode fiber was pumped with an ytterbium-doped fiber laser system (FL) in CW regime at 1064 nm in a free running configuration. We showed that it is possible to obtain up to the N’th power thresholds and maximum power for each Stokes by using compact analytical solutions as a first approximation in an arguably simple, quick process.
There are basically five nonlinear phenomena that occur in the optical fiber which limits the power or distort the signal in the data transmission. One of the most important is the phenomenon called Stimulated Brillouin Scattering (SBS) as it only requires relatively low pump power for affecting signal power in single and multiwavelength transmission in DWDM systems, for instance. There are numerous studies of this phenomenon that deal with power threshold determination which represents the limit on the transmit power but many of them are very complex and not very clear. In this work we propose a simple algorithm for the analysis and simulation of Brillouin power threshold by choosing a set-point. The results are obtained via solving the proposed set of coupled differential equations which then are compared to experimental results for Brillouin and Rayleigh scattering and forward power, i.e. residual pump.
In this work, the evolution of the nth analytical solutions of traditional Raman equations including numerical
simulation and experimental results is done. In the experiment an 8.6 Km single mode fiber was pumped with an
ytterbium doped fiber laser system (FL) in CW regime at 1064-nm in a free running configuration. We showed that
it is possible to obtain up to the nth power thresholds and maximum power for each Stokes by using compact
analytical solutions such as first approximations in an arguably simple, quick process.
A simple experimental configuration for measurement of the Raman gain coefficient is demonstrated. The Raman
threshold condition plays a role important to calculate the critical power and the Raman gain coefficient. Analysis of the
Raman threshold for second Stokes shows that the Raman gain coefficient scales with the inverse of the pump
wavelength and the fiber attenuation, the obtained values are approximate to several quantities previously reported. With
those physical properties the single pass evolution of pump and Stokes beams equations are simulated for different fiber
lengths and several coupled pump powers. The numerical simulations show that the fibers losses and the numerical
aperture play a predominant role in the Stokes generation. These results allow designing optical fibers efficient and/or
poor in the Stimulated Raman scattering generation.
The critical power level provides an objective tool for the determination of the maximum power available in a fiber laser based
on physical parameters as: core diameter, temperature, and absorption and emission cross section for both the pump and laser
wavelengths. This work presents a theoretical study of critical power levels when Ytterbium-doped fibers are exposed to
changes of temperature. We found that critical power curves extend their wavelength dependence, ranging from 1 μm to 1.2 μm
when fibers were heated up 300°K. Also we found that critical power values are large than those obtained in conditions of room
temperature. While low critical powers were obtained at lower temperatures (around 77°K) with a reduced interval of
wavelengths from 1 μm to 1.1 μm.