Nonlinear optical effects

Determination of atomic level populations by generation of third-harmonic ultrashort optical pulses

Yu. P. Malakyan, D. G. Sarkisyan, A. S. Sarkisyan


Abstract: A simple method of measuring atomic level populations was implemented by comparing the energies of the third harmonic generated by two identical ultrashort pulses. When the first ultrashort pulse induces a process that removes some of the atoms from the ground (initial) level for third harmonic generation, the energy of the second third-harmonic pulse W_th2 becomes lower than W_th1 as a result of a reduction in the number of atoms. In the experiments К = W_th1 / W_th2 increased as the ultrashort pulse intensity increased. Experimental investigations and theoretical estimates showed that the most probable process causing a reduction in the population of the 6²S_1/2 level of cesium atoms was multiphoton ionization. It was found that the degree of multiphoton ionization could be estimated from K.

UDC: 621.372.632

PACS: 42.65.Re, 42.65.Ky, 32.80.Bx, 32.80.Wr

Received: 10.08.1990

 English version: Soviet Journal of Quantum Electronics, 1991, 21:8, 849–853

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