AC-Stark effect

Tamarat P, Lounis B, Bernard J, Orrit M, Kummer S, Kettner R, Mais S and Basche T 1995 Pump-probe experiments with a single molecule ac-Stark effect and nonlinear optical response Phys. Rev. Lett. 75 1514-17... 

Figure 6.9 Generic five-state system for ultrafast efficient switching. The resonant two-state system of Figure 6.6 is extended by three target states for selective excitation. While the intermediate target state 4) is in exact two-photon resonance with the laser pulse, both outer target states 3) and 5) lie well outside the bandwidth of the two-photon spectrum. Therefore, these states are energetically inaccessible under weak-field excitation. Intense femtosecond laser pulses, however, utilize the resonant AC Stark effect to modify the energy landscape. As a result, new excitation pathways open up, enabling efficient population transfer to the outer target states as well.

The AC Stark effect is relevant, not only in atomic spectroscopy, but also in solid state physics. The biexciton state (or excitonic molecule), where two Wannier excitons are bound by the exchange interaction between electrons, occurs in various semiconductors (see section 2.22). Various experiments on the AC Stark effect of excitons have been reported, but the clearest example to date is probably the observation of the Rabi splitting of the biexciton line in CuC reported by Shimano and Kuwata-Gonokami [477]. It is very interesting to consider how Bloch states in solids, which themselves are delocalised and periodic, are dressed or modified by the electromagnetic field, since their properties are rather different from those of purely atomic states, which are by definition completely localised. 

The error is a systematic error arising from ac Stark effect, second order Doppler shift, a frequency offset between the cw dye laser oscillator and the high-powered pulsed amplifier output and laser metrology. Substantial improvement in the accuracy of this measurement appears technically feasible. The current theoretical value is(6,15)... 

In Section 1.3 the shift of the single molecule excitation line under the influence of a static electric field, the DC Stark effect, is discussed. The interaction of molecular electronic energy levels with a strong optical field is also expected to lead to level shifts and splittings and additionally to a change of relaxation rates. The shift of energy levels under optical excitation is called light shift or AC Stark effect where... 

The strong inhomogeneous broadening of optical transitions in solids at low temperature prevented the observation of the AC Stark effect within an ensemble of molecules. In this case also line narrowing techniques did not provide a solution to realize the experiment. With the advent of single molecule spectroscopy the proper means to perform experiments of the piunp-probe type on absorbers in solids without excessive interfering backgrounds were available. Due to the favourable photo-... 

In the case of measurements at a cavity temperature of 2K [15], a reduction of the signal could be clearly seen for atomic fluxes as small as 800 atoms/s. An increase in flux caused power broadening and finally an asymmetry and a small shift (Fig. A). This shift is attributed to the ac Stark effect, caused predominantly by virtual transitions to the 6ld level, which is only 50MHz away from the maser transition (Fig. 3). the fact that the field ionization signal at resonance is independent of the particle flux (between 800 and 22 x 10 atoms/s) indicates that the transition is saturated. This, and the observed power broadening show that there is a multiple exchange of photons between Rydberg atoms and the cavity field. 

Prineas JP, Zhou JY, Kuhl J et al. Ultrafast ac Stark effect switching of the active photonic band gap from Bragg-periodic semiconductor quantum wells. Applied Physics Letters 2002 Dec 2 81(23) 4332-4334. 

External electric field applied to a medium shifts the energy levels. It results in a change of absorption spectrum (blue shift) and this phenomenon is called DC or AC Stark effect. The same effect one observes at optical frequencies. The shift of optical absorption spectrum is... 

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