RESUMO
We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064â nm pulsed beams propagate from wider (122â µm) into smaller (37â µm) diameter. In the passive mode, increasing the input beam peak power above 20â kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600â nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length.
RESUMO
A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.
Assuntos
Tecnologia de Fibra Óptica/instrumentação , Lasers de Estado Sólido , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestrutura , Refratometria/instrumentação , Transferência de Energia , Desenho de Equipamento , Análise de Falha de EquipamentoRESUMO
The experience of intensive therapy of 23 patients with infiltrative pulmonary tuberculosis is presented. The complex approach that permits to solve the problem of resistant Mycobacterium tuberculosis and chemotherapy poor tolerance is substantiated.