Imagerie IRM 3D appliquée au phénotypage des semences et des plantules

Rapport de stage du Master 2 de Physique, spécialité Photonique Signal Imagerie, Université d'Angers.&nbsp;</p

Study of a harmonic mode lock stability under external continuous-wave injection

In this paper, we investigate experimentally the effect of an injected continuous external optical laser in a stable passive harmonic mode-locked fiber laser operating in the anomalous dispersion regime. Under specific conditions, the continuous-wave significantly increases the stability of the harmonic mode-locked regime. This occurs for a discrete set of wavelengths and below a critical injected power

Harmonic dissipative soliton resonance square pulses in an anomalous dispersion passively mode-locked fiber ring laser

We demonstrate the generation of dissipative soliton resonance square pulses from a co-doped Er:Yb double-clad fiber ring laser operating in an all anomalous dispersion regime. The obtained pulses have a repetition rate of 672 kHz and a pulse energy of 409 nJ. By carefully adjusting the polarization controllers while increasing the pump power, the square pulse can split into a series of identical equally spaced smaller square pulses up to the 13th harmonic of the fundamental repetition frequency. The average output energy of the square pulses follows a scaling law versus the harmonic orde

Roadmap to high-energy square pulses in anomalous dispersion fiber lasers

Dissipative soliton resonance (DSR) is a soliton formation where the energy in a dissipative system becomes infinite. In the anomalous dispersion regime, this energy is not limited by the soliton area theorem. Since this phenomenon is wave breaking free, it can be useful in designing fiber lasers generating pulses with relatively high energies. Based on this principle, we have demonstrated the emission of high energetic square pulses from Er:Yb double-clad passively mode-locked fiber lasers using different mode-locking mechanisms. We first show the evolution of pulse width, energy and peak power by varying the pumping power of the amplifier, then we control separately the characteristic of the output square pulse by assigning each one to an amplifier. Experimental results exhibit record energies in fiber lasers up to 10 uJ

Spectral dynamics of square pulses in passively mode-locked fiber lasers

We investigate experimentally and numerically the spectral dynamics of square pulses generated in passively mode-locked fiber lasers under the dissipative soliton resonance. The features of the transition from the single-peak spectral profile to the doublet spectrum with increasing pump power are studied. The used master equation takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. Experimental data are obtained for an Er:Yb-doped fiber ring laser. The theoretical and experimental results are in good agreement with each other

Experimental optimization of dissipative soliton resonance square pulses in all anomalous passively mode-locked fiber laser

We investigate experimentally the operational boundaries of dissipative soliton resonance in a double-clad Er:Yb co-doped dual amplifier passively mode-locked figure-of-eight fiber laser. While mode-locking with a nonlinear amplifying loop mirror, we present an exhaustive series of experiments in order to optimize the pulse energy and pulse width tunability. In addition to the pumping power of the amplifiers, several key experimental parameters have been identified such as the net cavity dispersion, the coupling ratio between the two loops of the cavity and the exact position of the long fiber coils. Under optimized conditions, the laser delivers square pulses with an energy varying between 8.5 and 10.1 μJ while the pulse width ranges from 84-416 ns

Identification of Potential Glycoprotein Biomarkers in Estrogen Receptor Positive (ER+) and Negative (ER-) Human Breast Cancer Tissues by LC-LTQ/FT-ICR Mass Spectrometry

Breast cancer is the second most fatal cancer in American women. To increase the life expectancy of patients with breast cancer new diagnostic and prognostic biomarkers and drug targets must be identified. A change in the glycosylation on a glycoprotein often causes a change in the function of that glycoprotein; such a phenomenon is correlated with cancerous transformation. Thus, glycoproteins in human breast cancer estrogen receptor positive (ER+) tissues and those in the more advanced stage of breast cancer, estrogen receptor negative (ER-) tissues, were compared. Glycoproteins showing differences in glycosylation were examined by 2-dimensional gel electrophoresis with double staining (glyco- and total protein staining) and identified by reversed-phase nano-liquid chromatography coupled with a hybrid linear quadrupole ion trap/ Fourier transform ion cyclotron resonance mass spectrometer. Among the identified glycosylated proteins are alpha 1 acid glycoprotein, alpha-1-antitrypsin, calmodulin, and superoxide dismutase mitochondrial precursor that were further verified by Western blotting for both ER+ and ER- human breast tissues. Results show the presence of a possible glycosylation difference in alpha-1-antitrypsin, a potential tumor-derived biomarker for breast cancer progression, which was expressed highest in the ER- samples

Color domains in fiber lasers

We report on the experimental observation of a color domain (CD) phenomenon in a dissipative soliton fiber laser. The CDs are constituted by a wavelength-dependent condensed phase of pulses in motion. Single CD, dual CD, and tricolor domain that occupy all the cavity space are observed. The CDs have flexible tunability of duty cycle, amplitude, wavelength, and wavelength spacing. The CDs derive from the wavelength-dependent slow evolution of gain, and the formation mechanism of multiple CDs can be explained by cross gain saturation

Theory of passively-mode-locked fiber lasers with phase-modulated square pulses

We present results of the analysis of square pulses generated in passively-mode-locked lasers under dissipative-soliton-resonance conditions. The master equation used in this work takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. The phase modulation effects are defined as a perturbation to the solution of this equation that has the form of a square pulse without phase modulation. An analytical dependence of the change in the carrier frequency of the radiation along the pulse is found. Conditions for the occurrence of the singlet and doublet spectra of the square pulse are determined. The mechanisms responsible for the occurrence of this regime are analyzed. The obtained analytical dependencies are in good agreement with the results of numerical simulation