Influence of classical pump noise on long-pulse multiorder stimulated Raman scattering in optical fiber (original) (raw)
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Optics Communications, 2001
We present an experimental and theoretical investigation of the eects of pump pulse temporal structure on cascade Raman generation in the quasi-continuous wave regime. The growth and saturation of the Stokes pulse energies depend very strongly on the pump pulse temporal envelope and substructure. Experiments and simulations on the growth of the total Stokes pulse energy and the energy in a narrow central slice highlight the importance of knowing the detailed pump pulse temporal structure. Experimentally measured growth curves for dierent Stokes orders could be transformed by a simple scaling to lie on a universal curve.
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.
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.
Temporal quantum fluctuations in stimulated Raman scattering: Coherent-modes description
Physical Review Letters, 1989
Temporal quantum fluctuations of the intensity of light pulses produced in the linear regime of stimulated Raman scattering are observed. A theoretical description based on the concept of coherent temporal modes is presented. The method makes use of a minimum number of random variables, which are the excitation amplitudes of the temporal modes, and allows an estimate of the probability for generating a Stokes pulse that is likely to form a soliton in the nonlinear propagation regime. PACS numbers: 42.50.p, 42.65.k Several interesting aspects of the generation of macroscopic light fields by quantum-initiated stimulated Raman scattering (SRS) have been clarified in recent years. Using the Heisenberg-picture quantum theory of SRS, ' full-scale fluctuations of macroscopic Stokespulse energies were predicted and observed. 45 The agreement between theory and experiments supports the assertion that the statistics of the spontaneously generated Stokes field are thermal-like (i.e. , Gaussian) in the absence of molecular saturation or pump-laser depletion. In parallel developments, Druhl, Wenzel, and Carlsten
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.
Origin of uniform pump-to-Stokes relative intensity noise (RIN) transfer in Raman fiber lasers
Recently, the uniform pump-to-Stokes relative intensity noise (RIN) transfer has been discovered for cascaded Raman fiber lasers [1]. It was found that peaks of the radiofrequency (RF) spectrum associated with longitudinal mode beating in the pump laser cavity almost uniformly transfer to the 1st and 2nd Stokes RF-spectra. Here we present a detailed derivation of the analytical expression that explains this effect. We show that interaction between the intensity noise fluctuations related to counter-propagating waves in the Raman cavity is negligible comparing with the interaction of co-propagating fluctuations. This feature results in a simple relation between the fluctuation intensities.
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.
2014 International Conference on Electronics, Communications and Computers (CONIELECOMP), 2014
Scattering (SRS) in conventional short fibers (8m) to supercontinuum generation is reported. Here we used short length optical fibers pumped with a microchip laser emitting a pulsed signal at 1064 nm wavelength and 700ps. Moreover was obtained a detailed analysis of spectral evolution of pulses propagated through the fiber. Hence MI is observed as first nonlinear effect unchaining more of those until reach a 293 nm wide spectrum. A comparative analysis was done between 1060XP and SM28 short section optic fibers showing important SRS gaining differences, achieving on SMF28 fiber a higher gain on anti-Stokes wavelength. On the other side was achieved a higher broadening spectral on 1060XP fiber than the one generated on communications optical.
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. #
Stochastic phenomena in a fiber Raman amplifier
Annalen der Physik, 2016
The interplay of such cornerstones of modern nonlinear fiber optics as a nonlinearity, stochasticity and polarization leads to variety of the noise induced instabilities including polarization attraction and escape phenomena harnessing of which is a key to unlocking the fiber optic systems specifications required in high resolution spectroscopy, metrology, biomedicine and telecommunications. Here, by using direct stochastic modeling, the mapping of interplay of the Raman scattering-based nonlinearity, the random birefringence of a fiber, and the pump-to-signal intensity noise transfer has been done in terms of the fiber Raman amplifier parameters, namely polarization mode dispersion, the relative intensity noise of the pump laser, fiber length, and the signal power. The obtained results reveal conditions for emergence of the random birefringence-induced resonance-like enhancement of the gain fluctuations (stochastic anti-resonance) accompanied by pulse broadening and rare events in the form of low power output signals having probability heavily deviated from the Gaussian distribution.