RESUMEN
The complete mitochondrial genome (mitogenome) sequence of Achalinus rufescens was determined by using a PCR-based method. The total length of mitogenome is 17,339 bp and contains 13 protein-coding genes, 22 tRNA genes, 2 ribosome RNA genes and 2 control regions (D-loop). All the protein-coding genes of A. rufescens were distributed on the H-strand, except for the ND6 subunit gene and eight tRNA genes which were encoded on the L-strand. The phylogenetic tree of A. rufescens and 11 other closely species was built. The DNA data presented here will be useful to study the evolutionary relationships and genetic diversity of A. rufescens.
RESUMEN
The theoretical research of supercontinuum (SC) generation in a fiber amplifier system has been seldom reported. For the purpose of further understanding the mechanism of SC generation in fiber amplifiers, we propose a combined numerical model of the laser rate equations and the generalized non-linear Schrödinger equation to simulate the amplification of 1060 nm picosecond pulses and their spectral broadening in an ytterbium-doped fiber amplifier. The calculation results of this model are compared with the experimental results under the same conditions and a good agreement is achieved. We find that the pulse is gain amplified initially, and then dominated by stimulated Raman scattering in the normal dispersion region. In anomalous dispersion region, modulation instability, higher-order soliton fission and soliton self-frequency shift dominates the spectral broadening. It is found numerically and experimentally that the length of the gain fiber and the 976 nm pump power are the most imperative parameters to control the output power, spectral range and flatness of the SC. The pulse width of signal pulse also plays a part in influencing SC generation. The results verify that our model is promising for analyzing the physical processes of pulse evolution and SC generation in a fiber amplifier system.
RESUMEN
We report an all-fiber linearly-polarized (LP) supercontinuum (SC) source with high average power generated in a polarization-maintaining (PM) master-oscillation power-amplifier (MOPA). The experimental configuration comprises an LP picosecond pulsed laser and three PM Yd-doped fiber amplifiers (YDFA). The output has the average power of 124.8 W with the spectrum covering from 850 to 1900 nm. The measured polarization extinction ratio (PER) of the whole SC source is about 85% which verifies the SC an LP source. This work is, to our best knowledge, the highest output average power of an LP SC source that ever reported. The influence of PM fiber splicing method on the LP SC property is investigated by splicing the PM fibers with slow axis parallel or perpendicularly aligned, and also an LP SC with low output power is demonstrated.
RESUMEN
We propose three theoretical models to evaluate the beam quality of the fiber supercontinuum source as a whole. New definitions of spectral centroid and three factors to evaluate the beam quality of supercontinuum source are introduced. Based on the three factors some supercontinuum sources with different output power and spectra obtained from the experiment are calculated numerically. All the results denote that the three models are feasible and useful for the beam quality evaluation and comparison of the fiber supercontinuum sources as a whole with considering the power spectral distribution and propagation modes.
