Effects of pump pulse temporal structure on long-pulse multi-order stimulated Raman scattering in optical fiber (original) (raw)
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Journal of The Optical Society of America B-optical Physics, 2002
We present a combined experimental and theoretical study of the effect of pump pulse noise on the growth and statistics of multiorder stimulated Raman scattering in optical fiber. Because of the intensity dependence of stimulated Raman scattering, fluctuations in the detailed temporal structure of the pump pulse amplitude strongly affect the growth and statistics of the Stokes orders, even when dispersive effects are not important. By comparing experimental results with a detailed model including the frequency dependence of the Raman gain and the pump pulse temporal structure, we show that the pump pulse temporal fluctuations play a pivotal role in determining the growth and pulse energy statistics of the Stokes orders.
Analysis of spectral broadening dominated by cascaded stimulated Raman scattering in optical fibers
Suplemento de la Revista Mexicana de Física, 2021
In this work, the experimental study of spectral broadening due to stimulated Raman scattering with respect to variation of input power of pulsed laser, as well as a 4 m length high-numerical aperture fiber with 100 and 500 m of non-zero dispersion-shifted fiber is reported. The results showed extreme broadening of spectrum which is known as supercontinuum generation, originated by self-phase modulation, four- wave mixing and dominated by cascaded stimulated Raman scattering. Supercontinuum spectrum achieved by total width of 850 nm and a remarkable flatness in the range of 1500 to 1600 nm. Furthermore, output spectrum showed a total of five Stokes waves. Numerical results are also presented.
Quasi-stationary multiple stimulated Raman generation in the visible using optical fibers
Applied Optics, 1983
Several orders of stimulated Raman scattering (SRS) in monomode and multimode fibers have been observed. The relatively low power in the visible used in the quasi-stationary regime permitted observation of sharply defined Stokes and anti-Stokes spectral lines without any continua. Results of pump-to-Stokes power conversion in a monomode fiber indicate a striking equivalence between pump power and fiber length.
Optics Express, 2005
We report experimental observations of stimulated Raman scattering in a standard fiber using a directly modulated DFB semiconductor laser amplified by two erbium-doped fibers. The laser pulse width was variably controlled on a nanosecond-scale; the laser emission was separated into two distinct regimes: an initial transient peak regime, followed by a quasi steady-state plateau regime. The transient leading part of the pump pulse containing fast amplitude modulation generated a broadband Ramaninduced spectral shift through the modulation instability and subsequent intra-pulse Raman frequency shift. The plateau regime amplified the conventional Stokes shifted emission expected from the peaks of the gain distribution. The output signal spectrum at the end of a 9.13 km length of fiber for the transient part extends from 1550 nm to 1700 nm for a pump pulse peak power of 65 W. We found that the Raman-induced spectral shift is measurable about 8 W for every fiber length examined, 0.6 km, 4.46 km, and 9.13 km. All spectral components of the broadband scattering appear to be generated in the initial kilometer of the fiber span. The Stokes shifted light generation threshold was higher than the threshold for the intra-pulse Raman-induced broadened spectra. This fact enables the nonlinear spectral filtering of pulses from directly modulated semiconductor lasers.
Evolution of the nth Stokes-wave due to stimulated Raman scattering in single-mode fibers
Optical Review, 2014
The evolution of the nth analytical solutions of commonly used Raman equations, analyzed by numerical simulation and experimentally, is reported. In the experiment, a 1 km undoped single-mode fiber was pumped with an ytterbium doped fiber laser system (FL) in continuous wave regime at 1064 nm in a free running configuration. We showed that it is possible to obtain up to the nth power thresholds and the maximum power for each Stokes wave by using compact analytical solutions as a first approximation in a simple, quick process. #
Proceedings of SPIE, 2003
We report a self-starting gigantic pulse generation observed during steady state stimulated Raman scattering (SRS) process in 10 km long telecom fiber. In our rather specific experimental configuration, the fiber was pumped by radiation from a 2.4 W continuous wave (CW) fiber laser source operating at 1455 nm. This pump provided the generation of light at Raman shifted wavelength around 1555 nm. At pumping face, the fiber was spliced with a broadband fiber loop mirror that reflected ~80% of Stokes power back into the fiber. Reflection from the far fiber end face was strongly prevented by the use of an optical isolator. The configuration provided ~30% power conversion from pump to Stokes radiation. Pulsations were observed from both ends of the fiber and occurred in rather stochastic manner with repetition rates in the range from hundreds kilohertz to several megahertz. Gigantic pulses with duration down to ~1 ns and peak power estimated to be above ~1 kW were recorded from the far fiber end. Smaller pulses with duration down to ~50 ns were observed from the pumping side of the fiber. Using a digital oscilloscope we investigated the fine structures of the pulses and determined some consistent patterns of their mutual dynamics. The RF spectrum measurements highlighted the stimulated Brillouin scattering that is suspected to be a main dynamical mechanism initiating pulsations. We observed also other different nonlinear effects caused by propagation of the intensive pulses through the fiber. Corresponding optical spectra were recorded and interpreted. Reported experimental data indicate that Rayleigh, Brillouin and Raman scatterings are all involved in the process of gigantic pulse generation in the fiber.
Journal of the Optical Society of America B, 1999
We analyze the stimulated-Raman-scattering-(SRS) process induced by a linearly polarized multifrequency pump field in a normally dispersive single-mode fiber. We show, by theoretical analysis and numerical simulations, that the SRS process may be either controlled by switching all the generated Stokes radiations to the lowest-frequency pump or suppressed for all the frequency components of the pump field. The suppression process is achieved by an appropriate choice of the frequency separation between the pumps and a particular power distribution among the frequency components of the pump field. We present experimental spectra showing the effectiveness of this suppression process for a dual-frequency pumping configuration.