Distribution of Pumping Radiation Density in a Laser Crystal

Basem Abdul Ghani, M. Hammadi

A mathematical model describing the dynamic emission of intracavity polarized isotropic Cr 4+ :YAG solid--state saturable absorber was developed.This model considers double pumping laser pulses to simulate the actions of Cr 4+ :YAG as a dual Q-switched crystal (1.06 µm) and lasing medium (1.4 µm).The model describes the time evolution of interaction between the pumping laser pulse, partial polarizer and the polarized saturable absorber.The analysis of the polarization process is based on the assumption that at each moment of lasing evolution, the state of polarization represented by an eigenstate corresponds to the lowest radiation losses state.The model offers a simple mechanism for studying the kinetics of the pulsed lasers and the influence of the variations of the pumping laser power and nonlinear anisotropy parameter on the characteristics of the output laser pulses 1.06 µm and 1.4 µm.The angular rotation of the passive switch Cr 4+ :YAG reveals that the transmission of the polarized 1.06 µm laser radiation is strongly anisotropic in the saturation regime.The suggested model estimates the transmission of pumping laser density of the polarized light 1.06 µm radiation as a function of nonlinear anisotropy parameter, temporal behavior of the relative population inversion of Nd-laser, population inversion of the different polarized levels of Cr 4+ :YAG pulsed laser and the output laser pulse densities under impact of different values of the nonlinear anisotropy which is due to the self-induced anisotropy of its saturated absorption.

Walter E Thirring

P. P. Jauho, D.O. Riska, Stig Stenholm

Lucia Florescu

The emission spectrum of a single-emitter laser in a photonic crystal is presented. We consider a coherently pumped two-level emitter strongly coupled to a high-quality microcavity engineered within a photonic crystal. We show that the cavity spectrum consists of both elastic and inelastic components, for which we derive analytical expressions. Our study reveals enhanced, spectrally narrower emission resulting from the radiation reservoir of the photonic crystal. The cavity field spectral characteristics are fundamentally distinct from those of a corresponding microcavity in ordinary vacuum. At high pump intensities and for large discontinuities in the photon density of states between Mollow spectral components of atomic resonance fluorescence, the emitted intensity originating from the elastic spectral component increases with the intensity of the pump and the elastic component dominates the spectrum. In the case of a vanishing photon density of states in the spectral range surrounding the lower Mollow sideband and no dipolar dephasing, the cavity spectrum is elastic.

Yifan Shen

The effective radiative rate for Cs(6P3/2) resonance level in the presence of Ar is determined.Cs atoms were excited to the 6P3/2 state using a single-mode diode laser(pump laser).The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam(probe laser),tuned to the 6P3/28S1/2 transition which could be translated parallel to the pump beam.In the presence of radiation trapping,the spontaneous radiation rate is multiplied by the transmission factor T6p3/26S1/2,which describes the average probability that photons emitted within the fluorescence detection region can pass through the optically thick vapor without being absorbed.Position dependent 6P3/2 state densities had been combined with the collisional broadening rate 6P3/26S1/2 line due to both Ar and cesium perturbers to yield the T6p3/26S1/2.The effective radiative rates of the Cs D2 line as a function of the Ar pressure PAr were obtained.The fluorescence intensity I852 of the 6P3/26S1/2emission was measured simultaneously.The measured fluorescence ratios determined the ratios of the effective radiative rates at different Ar density.These ratios are in agreement with theoretical evaluation.

Н.С. Руденко, V. G. Konareva