14 research outputs found
Observation of Replica Symmetry Breaking in the 1D Anderson Localization Regime in an Erbium-Doped Random Fiber Laser
The analogue of the paramagnetic to spin-glass phase transition in disordered
magnetic systems, leading to the phenomenon of replica symmetry breaking, has
been recently demonstrated in a two-dimensional random laser consisting of an
organic-based amorphous solid-state thin film. We report here the first
demonstration of replica symmetry breaking in a one-dimensional photonic system
consisting of an erbium-doped random fiber laser operating in the
continuous-wave regime based on a unique random fiber grating system, which
plays the role of the random scatterers and operates in the Anderson
localization regime. The clear transition from a photonic paramagnetic to a
photonic spin glass phase, characterized by the probability distribution
function of the Parisi overlap, was verified and characterized. In this unique
system, the radiation field interacts only with the gain medium, and the fiber
grating, which provides the disordered feedback mechanism, does not interfere
with the pump
Turbulence Hierarchy in a Random Fibre Laser
Turbulence is a challenging feature common to a wide range of complex
phenomena. Random fibre lasers are a special class of lasers in which the
feedback arises from multiple scattering in a one-dimensional disordered
cavity-less medium. Here, we report on statistical signatures of turbulence in
the distribution of intensity fluctuations in a continuous-wave-pumped
erbium-based random fibre laser, with random Bragg grating scatterers. The
distribution of intensity fluctuations in an extensive data set exhibits three
qualitatively distinct behaviours: a Gaussian regime below threshold, a mixture
of two distributions with exponentially decaying tails near the threshold, and
a mixture of distributions with stretched-exponential tails above threshold.
All distributions are well described by a hierarchical stochastic model that
incorporates Kolmogorov's theory of turbulence, which includes energy cascade
and the intermittence phenomenon. Our findings have implications for explaining
the remarkably challenging turbulent behaviour in photonics, using a random
fibre laser as the experimental platform.Comment: 9 pages, 5 figure
Structural and optical properties of Nd:YAB-nanoparticle-doped PDMS elastomers for random lasers
ABSTRACT: We report the structural and optical properties of Nd:YAB (NdxY1−x Al3(BO3)4)-nanoparticle-doped PDMS elastomer films for random lasing (RL) applications. Nanoparticles with Nd ratios of x = 0.2, 0.4, 0.6, 0.8, and 1.0 were prepared and then incorporated into the PDMS elastomer to control the optical gain density and scattering center content over a wide range. The morphology and thermal stability of the elastomer composites were studied. A systematic investigation of the lasing wavelength, threshold, and linewidth of the laser was carried out by tailoring the concentration and optical gain of the scattering centers. The minimum threshold and linewidth were found to be 0.13 mJ and 0.8 nm for x = 1 and 0.8. Furthermore, we demonstrated that the RL intensity was easily tuned by controlling the degree of mechanical stretching, with strain reaching up to 300%. A strong, repeatable lasing spectrum over ~ 50 cycles of applied strain was observed, which demonstrates the high reproducibility and robustness of the RL. In consideration for biomedical applications that require long-term RL stability, we studied the intensity fluctuation of the RL emission, and confirmed that it followed Lévy-like statistics. Our work highlights the importance of using rare-earth doped nanoparticles with polymers for RL applications