Pulse formation and amplification in an absorbing medium by optical phase switching

B. Macke, J. Zemmouri, Bernard Ségard

Yury V. Kistenev

Petr P Vasil'ev

An analysis is made of the conditions for the generation of superfluorescence pulses in an inverted medium of electron—hole pairs in a semiconductor. It is shown that strong optical amplification in laser semiconductor amplifiers characterised by α L ≫ 1 (α is the small-signal gain and L is the amplifier length) leads to suppression of phase relaxation of the medium during the initial stages of evolution of superfluorescence and to formation of a macroscopic dipole from electron—hole pairs. Cooperative emission of radiation in this system results in generation of a powerful ultrashort pulse of the optical gain, which interacts coherently with the semiconductor medium. It is shown that coherent pulsations of the optical field, observed earlier by the author in Q -switched semiconductor lasers, are the result of superfluorescence and of the coherent interaction between the optical field and the medium.

M. I. Demchuk, I. A. Manichev, V. P. Mikhailov

A system of partial differential rate equations for a population inversion in a medium and for the intensity of radiation propagating this medium is used in a numerical analysis of a single trip of a Gaussian pulse through a two-level two-component saturable absorber. Relationships governing the formation of regions of efficient compression of ultrashort pulses are identified and the possibility of controlling the maximum degree of reduction of pulse duration is considered. Two-component absorbers selected with the proposed recommendations can ensure the maximum efficiency of pulse compression in a trip when the input intensity is fixed and the input durations can vary within a wide range. The last circumstance makes such absorbers very promising as passive switches for solid-state lasers with passive mode locking and stabilization of the intensity of ultrashort pulses in order to minimize the duration of the output radiation.

Rafael V Ambartsumyan, Nicolai G. Basov, V. S. Zuev +2 more

Md. Aminul Islam Talukder