Coherent optical effects

There is another way of measuring of an optical transition which is not based on a coherent optical effect but also employs a coherence property of the laser, namely, its monochromaticity. In the hole-burning technique, as in the OFID method, a cw dye laser is used to create a hole in the absorption spectrum. When this hole is transient, its width, being determined in the low-intensity limit by 2( 7 ) , may be probed by side-band modulation as first demonstrated by Szabo on ruby. When the hole is permanent, as is the case in photochemical hole-burning, the width may be easily measured by means of a narrow-band excitation spectrum as first performed by de Vries and Wiersma on dimethyl j-tetrazine in durene. ... 

As the spacing ofthe real part ofthe eigenvalues Ej—Ef) is uncorrelated, one expects severe destructive interference effects for p(t), when more than a single ME is driven by the field. Thus, coherent optical effects such as photon echoes or free induction decay experiments can be conducted only under special excitation conditions as follows ... 

Jortner, J. and Kommandeur, J. (1978) Some features of coherent optical effects in large molecules. Chem. Phys., 28, 273. 

In a heavy fermion compound Yb MnSbn, the dephasing rate of the coherent optical phonons decreased with lowering temperature above Curie temperature Tc, but increased below Tc- The results were attributed to the coupling between an optical phonon mode and the Kondo effect [100]. 

In conclusion, we have presented a reliable method for selective production and detection of high-order atomic polarization moments based on the nonlinear magneto-optical effects with frequency modulated light. This method can be used for the selective control of higher order atomic coherences in multilevel systems exploiting large Kerr nonlinearities for the construction of all-optical quantum phase gates. 

Finally, it is important to realize that the development and improvement of characterization techniques rely heavily on instrumental developments, a fact that can not be overemphasized. After all, nonlinear optical effects were not known until the invention of a highly coherent and powerful enough light source, the laser. 

A good introduction to electro- and magneto-optical effects can be found in the book by Harvey on Coherent Light [158]. The main effects and the relationship between them are indicated in table 4.1. Many atoms are readily produced as vapour columns, using standard laboratory methods [159]. The natural mode in which to conduct experiments on unperturbed free atoms is therefore in transmission. As table 4.1 emphasises (the reason is given below), the Faraday effect contains equivalent information to the Zeeman effect in transmission. Actually, what Harvey calls the Zeeman effect in transmission is usually referred to as the inverse Zeeman effect [160], to distinguish it from the Zeeman effect observed in emission.5... 

There are several classes of optical effects induced by an internal perturbation, such as saturation of absorption, coherent Raman spectroscopy, multi-photon absorption processes, coherent transient spectroscopy (see Table 0.3). Section 5.1 of this chapter deals with saturation of absorption and multi-photon absorption processes. Section 5.2 outlines the principles of coherent anti-Stokes Raman spectroscopy (CARS), Raman-induced Kerr effect spectroscopy (RIKES), four-wave mixing (FWM), and photon echo. 

In the introduction to this chapter we gave an intuitive explanation of the origin of nonlinear optical effects and stressed the key role played by high power lasers and coherent light beams. These two concepts are defined here. We will describe one specific characteristic of laser light, namely the absorption saturation, and finally we will discuss susceptibility and frequency conversion of light. 

In the section on photochemical hole-burning it has become clear that in all photoexcitation experiments the role of the triplet state needs to be investigated. In Section IV we have presented a density matrix equation which is able to describe coherent optical transients effects in a system of coupled states. This equation is ... 

Near Infrared. Wavelength range from about 750 nm to 3 pm. Optical Parametric Oscillator. Uses nonlinear optical effects in a crystal to split the pump beam into two coherent output beams of tuneable wavelength. The sum of the reciprocal output wavelengths is equal to the reciprocal input wavelength. 

M.M. Kash, V.A. Sautenkov, A.S. Zibrov, L. Hollberg, G.R. Welch, M.D. Lukin, et al., Ultraslow group velocity and enhanced nonlinear optical effects in a coherently driven hot atomic gas, Phys. Rev. Lett. 82 (1999) 5229. 

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