π - Pulse propagation in nonlinear amplifiers

George L. Lamb

Masataka Nakazawa, Kazunori Suzuki, Yasuo N. Kimura +1 more

Coherent \ensuremath{\pi}-pulse propagation with pulse breakup has been observed in an erbium-doped fiber waveguide amplifier. The waveguide was pumped by a 1.48-\ensuremath{\mu}m ${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ga}}_{\mathit{x}}$${\mathrm{As}}_{\mathit{y}}$${\mathrm{P}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$ laser diode. The waveguide had an erbium ion concentration of 8900 ppm and was cooled to 4.2 K. The pulse source was a 1.53-\ensuremath{\mu}m mode-locked Er-doped glass laser with a pulse width of 400 ps. A pulse advance of approximately 130 ps was observed between a low-intensity transmitted pulse with a low pump power and an amplified \ensuremath{\pi} pulse in a 1.5-m-long fiber.

M. B. Krylov, С. В. Сазонов

The effect of transverse perturbations on the propagation of electromagnetic π pulses in an amplifying two-level medium is studied. The cases of quasi-monochromatic and extremely short pulses are considered. The equations describing the behavior of the transverse size of the pulse during its propagation in the medium are derived. It is shown that, if the ratios of the diffraction length to the length of dispersion spreading are smaller than certain critical values, self-focusing regimes are realized for both types of pulses. Otherwise, at a finite distance, blowup of defocusing occurs, after which the amplified pulse propagates as if it is a one-dimensional pulse, with the velocity equal to the velocity of light in vacuum. Similarities and distinctions in the dynamics of propagation of extremely short and quasi-monochromatic pulses are indicated.

Erwin Louis Hahn

S. Kh. Shavratskii

An analysis is made of the propagation of 2π pulses in an amplifying medium exhibiting polarization relaxation and nonresonant linear losses. It is shown that the combined influence of such relaxation and losses may stabilize 2π pulses. Changes in the pulse parameters and their asymptotic values are considered. The distance in which there is a characteristic change in the pulse parameters is estimated for ruby laser radiation.