Self-Pulsing in Laser Amplification of Broadband Noise

Norman Duane Wright, Maurice C. Newstein

Lanqin Liu, Jingqin Su, Luo Bin +4 more

Physical model was established to describe the broadband pulsed laser amplification processes. In this model, Cross relaxation was introduced to study the transformation of homogeneous and inhomogeneous population inversion after laser passage. Hybrid-widened linewidth, homogeneity and inhomogeneity were emphatically considered, which were had not been take into account in other models. Based on the physical model, computer simulation software CPAP for broadband pulse laser amplification process was developed. At last, we discussed the possibility that this broadband physical model can be transfered to the narrow_band physical model under certain conditions.

S. P. Bondarev

I. V. Kuzmin, Sergey Yu. Mironov, E. R. Kocharovskaya

The features of broadband chirped infrared laser pulses amplification by using a numerical solution of the Maxwell-Bloch equations for a four-level medium are considered in this work.

P. L. Knight

Lionel N. Menegozzi, Willis E. Lamb

The amplification of noise in a laser amplifier is treated theoretically. The model for the active medium and its description using density-matrix techniques, are taken from the theory of laser operation. The fundamental concern of this investigation is the spectral behavior of the radiation in the nonlinear regime; hence, the formalism is written from the onset in the frequency domain. The statistics of the light are gradually modified by the nonlinear amplification process, and expressions are derived for the rate of change of fluctuations in intensity as a measure of statistical changes. These expressions should be easily susceptible to detailed experimental observations. In addition, the range of validity of Litvak's Gaussian-statistics approximation is discussed with some detail. In the homogeneous-broadening case, the evolution of initially broadband Gaussian radiation toward quasimonochromatic oscillations with laserlike statistics is extensively explored in several numerical examples. The connections of this study with the time-domain work of Risken and Nummedal, on self-pulsing in a ring-laser configuration, are clearly established. Finally, spectral-narrowing and -rebroadening effects in Doppler-broadened media are discussed both analytically and with numerical examples. These examples show the distinct contribution of pulsations in the population ("Raman-type terms"), and saturation phenomena. The predicted narrowing-rebroadening rate is compared with expressions found in previous literature.