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We demonstrate a fibre laser with a mirrorless cavity that operates via Rayleigh scattering amplified through the Raman effect. The properties of such random distributed feedback laser appear different from those of both traditional random lasers and conventional fibre lasers.
In this paper we review some recent results related to the application of ultra-long Raman fibre laser (URFL) cavities to quasi-lossless optical signal transmission. In an URFL, the transmission fibre itself is contained inside a laser cavity delimited by two fibre Bragg gratings, allowing for a more efficient distribution of the Raman gain to the transmitted signal. We explore the unique properties...
We study the effect of fibre base and grating profile on the efficiency of ultra-long Raman lasers. We show that for the studied parameters, FBG profile does not affect the performance when operating away from the zero-dispersion wavelength.
Supercontinuum generation in ultra-long Raman fibre laser cavities is compared for a range of fibre dispersions in the anomalous and normal regimes. For normal dispersion improved performance and efficiency is achieved using dual wavelength pumping.
We study the impact of the shape of fibre Bragg gratings spectral reflectivity on spectral broadening in a 10 km Raman fibre laser. We show that, at high powers, spectral characteristics are determined by intra-cavity processes rather than by the gratings profile.
Supercontinuum generation in a multi-fibre ultra-long Raman fibre laser cavity is investigated experimentally. By using this cavity configuration we demonstrate improved spectral flatness and supercontinuum generation efficiency.
We present the first experimental demonstration of true (not loss managed) soliton pulse transmission in conventional optical fibre. Experimental FROG spectrograms and numerical simulations confirm the soliton pulse evolution dynamics.
We present the first experimental demonstration of a Raman fibre laser operation with a resolvable ~0.6 kHz mode spacing operating at 1551 nm. Our laser has a record cavity length of 165 km.
Performance optimization of ultra-long Raman laser links is studied theoretically and experimentally. We demonstrate that it is possible to reduce the signal power excursion by adjusting FBG reflectivity without compromising pump efficiency. Furthermore, we experimentally demonstrate an OSNR improvement of 4.3dB in our system after 4000km transmission by switching from conventional erbium-doped fibre...
In this paper we have experimentally demonstrated for the first time that the mode structure can be resolved up to the record laser cavity length of 84 km. Very narrow RF peaks reveal that the relative phase fluctuations between the neighbouring modes are very small even propagating through such a long span, but with increasing power they broaden significantly due to nonlinear interaction. Thus, our...
The turbulent nature of the generation of multiple cavity modes in ultra-long Raman fiber lasers is demonstrated in this study. Observations show turbulence-induced broadening of the intra-cavity spectrum and formation of clearly pronounced exponential tails at the power level as small as ~0.1 W. This broadening is likely to occur due to nonlinear four-wave mixing.
Intra-cavity spectra of ultra-long (up to 84 km cavity length) Raman lasers have been measured and simulated. The results demonstrate FWM-induced turbulent-like (involving up to 108 modes) broadening of the spectrum with clear exponential tails.
Performance optimisation of ultra-long Raman laser links is studied theoretically and experimentally. We observe that it is possible to reduce signal power excursion by adjusting FBG reflectivity without compromising pump efficiency.
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