SELECTIVE EXCITATION OF A 3-LEVEL ATOMIC SYSTEM - MODULATION EFFECTS OF ENERGY DENSITY AND DURATION OF PULSED LASERS TUNED NEAR 2-PHOTON RESONANCE

In the situation of a three-level atomic system, where two coherent pu lsed lasers are tuned near the two-photon resonance to completely achi eve a population transfer from the first level to the third one, the m odulation effects of the laser-pulse power and the duration on the sel ective excitation are examined numerically using the Bloch equation. A s a result, it is found that an analytic expression for the homogeneou s bandwidth of the optimal detunings is useful to obtain information c oncerning the effects, irrespective of the pulse-shape. It is remarkab le that the selectivity of specific isotopes in a medium can be signif icantly enhanced by a reduction of the pulse duration though it can be nearly independent of the laser power. The selective excitation using the optimal detuning method is compared with that using another metho d, the so called the pulse-time-ordering.