Three-level laser system

The active medium also determines the pumping scheme. Commonly, two types of operational schemes are used to describe laser operation /oMr-/cvc/ and three-level laser systems ... 

Three-electrode system, 9 573 300-series stainless steels, 13 510-511 Three-level lasers, 14 666, 696 inversion in, 14 669 3M Corporation... 

U. Boscain, G. Chariot, J.-P. Gauthier, S. Guerin, and H.-R. JausUn. Optimal control in laser-induced population transfer for two- and three-level quantum systems. J. Math. Phys. 43(5) 2107-2132(2002). 

To understand these phenomena we first consider a three-level A system, compc of a lowest energy state E]), coupled radiatively to an intermediate state [A0),1 in turn is coupled radiatively to a third state E2) where E0 > E2 > E1. The coup1 is due to the combined action of two laser pulses of central frequencies co, ahd We assume (see Fig. 9.1) that oq, the pump pulse (labeled P), is in near rescin with a transition from to the bound state 2T0) and that co2, the dump pulse... 

EIT is based on the phenomenon of coherent population trapping [Harris 1997 Scully 1997 Liu 2001], in which the application of two laser fields to a three-level A system creates the so-called "dark state", which is stable against absorption of both fields. Dark states are also found in several other... 

Population inversion cannot be achieved in a two-level system, a material with two electronic states. At best, a nearly equal population of the two states is reached, resulting in optical transparency, when absorption by the ground state is balanced by stimulated emission from the excited state. An indirect method of populating the emitting excited state must be used. In a three-level laser (Figure 3.6, left), irradiation of the laser medium pumps an upper level 2, which is rapidly depleted by a nonradiative... 

Figure C2.15.4. (a) A three-level laser energy level diagram and (b) the ruby system.

Describe the advantage of a four-level laser system over a three-level type. 

Here we extend the simple three-level EIT system to mote complicated and versatile configurations in a multi-level atomic system coupled by multiple laser fields. We show that with multiple excitation paths provided by different laser fields, phase-dependent quantum interference is induced either constractive or destractive interfereiKe can be realized by varying the relative phases among the laser fields. Two specific examples are discussed. One is a three-level system coupled by bichromatic coupling and probe fields, in which the phase dependent interference between the resonant two-photon Raman transitions can be initiated and controlled. Another is a four-level system coupled by two coupling fields and two probe fields, in which a double-EIT confignration is created by the phase-dependent interference between three-photon and one-photon excitation processes. We analyze the coherently coupled multi-level atomic system and discuss the control parameters for the onset of constructive or destructive quantum interference. We describe two experiments performed with cold Rb atoms that can be approximately treated as the coherently coupled three-level and four-level atomic systems respectively. The experimental results show the phase-dependent quantum coherence and interference in the multi-level Rb atomic system, and agree with the theoretical calculations based on the coherently coupled three-level or four-level model system. 

Stimulated emission (SE) and lasing effects are found in plasma of atoms of elements from the 13th and 14th groups of the periodic table. Atoms of A1 and In in laser-induced plasma both possess a three-level lasing system. In T1 plasma both... 

It was shown above that the normal two-level system (ground to excited state) will not produce lasing but that a three-level system (ground to excited state to second excited state) can enable lasing. Some laser systems utilize four- or even five-level systems, but all need at least one of the excited-state energy levels to have a relatively long lifetime to build up an inverted population. 

Fig. 1. Pumping methods for lasers where is the pump light frequency and is the laser frequency, wavy lines represent radiationless transitions, and the dashed line collisions (a) optical pumping in three-level systems (b) optical pumping in four-level systems (c) pumping by electron impact and...

Figure 2. Representations of two- (left), three- (middle), and four-level (right) laser systems. Key GS, ground state ULL, upper laser level and LLL, lower laser...

J. R. Kuklinski, U. Gaubatz, F. T. Hioe, and K. Bergmann. Adiabatic population transfer in a three-level system driven by delayed laser pulses. Phys. Rev. A, 40(11) 6741-6744(1989). 

Figures 6a-c show the population dynamics encountered in a three-level system (see Fig. 4) interacting resonantly with two Fourier-transform-limited laser pulses with three different delay times between the two pulses. The calculation was done assuming that the chosen Rabi frequencies fulfill the relation > 1/pulse duration) in all three cases. This relation ensures that the typical time for a Rabi oscillation of the population in an isolated two-level system is shorter than the pulse duration. Ionization from level 2 was introduced as a fast laser intensity-dependent decay of level 2 [6, 60], and resonant laser frequencies were assumed.

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