Optical coherence effects

Wynne K and Hochstrasser R M 1993 Coherence effects in the anisotropy of optical experiments Chem. Phys. 171 179-88... 

Conversely, we may observe an exceedingly narrow spectral line, so that o(x ) is approximated by <5(x ). Now the data i(x) represent the response function. This principle can, in fact, be used to determine the response function of a spectrometer. The laser, for example, is a tempting source of monochromatic radiation for measuring the response function of an optical spectrometer. Coherence effects, however, complicate the issue. We present further detail in Section II of Chapter 2. 

I. Is it possible to observe a shift in coherent Raman scattering in the three-level system with A-type coupling We have done an experiment to obtain a femtosecond Raman gain spectrum in polydiacetylenes. The Raman spectrum is shifted to the red under increased pump (to i) intensity. By changing o>2> the amplification peak signal is to be shifted to lower frequency. If the optical Stark effect is observed, then, in principle, it should be possible to observe the effect of a high field on the coherent Raman spectrum (see Fig. 1). 

Subtenon local injection of a glucocorticoid is effective in the treatment of certain forms of uveitis. Central serous chorioretinopathy, confirmed by optical coherence tomography, developed after a single local subtenon glucocorticoid injection to treat HLA-B27-associated iritis (70). 

The pump induced transient polarisation of the medium modifies the polarisation state of a time delayed probe pulse. Phenomenologically, this process can be regarded as a transient pump induced linear or circular birefringence, also called the Specular Optical Kerr Effect (SOKE) and the Specular Inverse Faraday Effect (SIFE) [18], These are cubic non-linear effects and are predicted to exist from symmetry arguments. Both effects consist of coherent and incoherent parts. For the coherent part, the pump drives the coherent electron-hole pair that affects the probe polarisation. The effect depends upon the probe phase relative to that of the electron-hole pair, and hence, that of the pump. For the incoherent part of the SIFE and the SOKE, the relative pump-probe phase is not important, since the probe pulse polarisation is modified by the pump induced sample polarisation that survives after the decoherence of the electron-hole pair. 

While a large number of coherent, time-domain, low-frequency Raman spectroscopies have been developed (15-18), they all fall under the general category of optical Kerr effect (OKE) spectroscopy (19,20). The Kerr effect is a phenomenon that occurs when a polar liquid is subjected... 

The phenomenon of optical interference is commonly describable in completely classical terms, in which optical fields are represented by classical waves. Classical and quantum theories of optical interference readily explain the presence of an interference pattern, but there are interference effects that distinguish the quantum (photon) nature of light from the wave nature. In this section, we present elementary concepts and definitions of both the classical and quantum theories of optical interference and illustrate the role of optical coherence. 

Theorists have also considered the yet to be tapped capabilities of lasers and have recently centered attention on coherence effects. Consider the probability to observe a set of final states pf following optical excitation of an initial state i> by a weak field. This can be written as... 

Thin Films. When geometric optics cannot be applied, coherence effects require that electromagnetic wave theory be applied until extremely thin films are treated. For example, the normal reflectance R of a thin nonabsorbing film of refractive index n, on a substrate with refractive index n2 is found to be... 

Films that are greater than a few wavelengths in thickness but not yet in the geometric optics region are treated by Chen and Tien [263], and a recent review of thin film and partial coherence effects as well as very thin film effects is in Chen [264]. 

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