Free induction decay optical measurements

Both measurements show a fast rising beat structure at negative delaytimes. The origin of this signal results from optical coherence generated by the linearly polarized probe pulse and corresponds to a first-order Free-Induction-Decay. An interpretation of this signal is found in ref. [2]. 

This optical induction free decay can be measured with a beat technique at time r = 0 the frequency cu of a cw laser is switched from co = con to aJ o) 2 out of resonance with the molecules. The superposition of the damped wave at o) 2 emitted by the coherently prepared molecules with the wave at co gives a beat signal at the difference frequency Aco = co 2— o), which is detected [12.70]. If Aco is smaller than the Doppler width, the laser at cu interacts with another velocity subgroup of molecules and produces optical nutation, which superimposes the free-induction decay and which is responsible for the slowly varying envelope in Fig. 12.21b. 

Dephasing can be studied either in the time domain (photon echo PE [171,172], optical free induction decay (OFID) [173, 174] or in the frequency domain (hole burning) [175-177]. With these techniques, the homogeneous broadening can be circumvented and the pure homogeneous width can be measured. 

This free optical induction decay can be measured with a beat technique at time t = 0 the frequency w of a CW laser is switched from w =... 

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