Polarization coherent

Cheng, J.-X., Book, L., and Xie, X. S. 2001a. Polarization coherent anti-Stokes Raman scattering microscopy. Opt. Lett. 26 1341-43. 

When the interface between a thin ( 50nm) film of free-electron metal (e.g., Au, Ag, or Al) and a glass prism is irradiated with a TM polarized coherent light, correlated motion of free electrons in the metal leads to the formation of oscillating charge at the metal/glass interface (Fig. 9.16)... 

Figure 1. Interaction geometry for two-pulse studies of polarization coherence.

To complete the comparison with the previous results obtained in Sections IV.C and IV.E, let us average the cosine operator in (114) over the states with two circularly polarized coherent modes a+, a ). We get... 

Finally, what is the role of IVR in photodissociation Very recently, we monitored the photodissociation of t-stilbene-He(Ar) complexes in real time (see Fig. 53)71 using polarized (coherent) excitation and analyzed product state distribution. The surprising finding was that the dissociation process, occurring subsequent to IVR, leaves bare t-stilbene in coherent rotational states (see Fig. 54 and compare the results with those in Fig. 47 for bare t-stilbene). The initial coherence induced in the... 

In all these time-resolved experiments the principles of pump-probe laser spectroscopy are the key element in the experimental design. A laser pulse is optically split into two components of unequal amplitude. The intense fraction, acting as a pump piilse, is directed towards the target or sample cell to trigger the molecular event under study. The much attenuated probe pulse monitors the absorption, raman scattering, polarization, coherence, or phase shift, which is linked explicitly to the dynamical observable under investigation. Extremely precise time... 

For most laser spectroscopy applications involving stimulated transitions of quantum systems between energy levels, the laser-light wave may be represented in the form of a linearly polarized coherent wave with frequency a and amplitude E,... 

Spontaneous nonlinear as well as coherent nonlinear Raman methods are considered here. These are based on the contributions of the nonlinear part of the induced dipole moment (spontaneous effects) or the induced polarization (coherent effects) to the intensity of the frequency shifted light. In the first case, the Raman signal is generated in a spontaneous, incoherent but nonlinear optical process, whereas in the second case the Raman information is contained in a coherent laser beam whereby the nonlinear polarization acts as a coherent light source. 

Cascini L, Ferlisi S, Peduto D, Fomaro G, Manunta M (2007) Analysis of DInSAR Data via geotechnical criteria. Rivista Italiana di Geotecnica 4 50-67 Cloude SR (2006) Polarization coherence tomography. 

Figure 9.4. Sinusoidal optical intensity profile produced by interference of two co-polarized coherent lasers.

Moreover, radiation which is polarization coherent possesses a finite component of angular momentiun at right-angles to the magnetic field B ahd this angular momentum is also transferred to the atoms at the moment of excitation. 

This calculation makes it clear that light beats are associated with the time evolution of the off-diagonal elements of the excited-state density matrix. Consequently they can only be observed in pulsed experiments if the light which excites the atoms of the sample is also polarization coherent. Only then is the necessary Hertzian coherence created in the excited-state density matrix. The theory predicts that modulation at the angular frequencies and will be detectable depending on the geometry and polarization used in the experiment. 

The central dynamical object that enters mto the polarization are the coherences of the fonn ( / t) p vj/ i(t)) and etc. These quantities are overlaps between wavepackets moving on different potential... 

The coherences can be written compactly using the language of density matrices. The total polarization is given by... 

A connnon teclmique used to enliance the signal-to-noise ratio for weak modes is to inject a local oscillator field polarized parallel to the RIKE field at the detector. This local oscillator field is derived from the probe laser and will add coherently to the RIKE field [96]. The relative phase of the local oscillator and the RIKE field is an important parameter in describing the optical heterodyne detected (OHD)-RIKES spectrum. If the local oscillator at the detector is in phase with the probe wave, the heterodyne mtensity is proportional to... 

This is followed by two field actions which again create a vibrational coherence but, now, with opposite phase to the first coherence. Hence one obtains a partial rephasing, or echo, of the macroscopic polarization. The final field action creates the seventh order optical polarization which launches the signal field (the eighth field). Just as for the spin echo in NMR or the electronic echo in 4WM, the degree of rephasing (tlie... 

Figure Bl.3.7. A WMEL diagram for the seventh order Raman echo. The first two field actions create the usual Raman vibrational coherence which dephases and, to the extent that inliomogeneity is present, also weakens as the coherence from different cliromophores walks oflP. Then such dephasing is stopped when a second pair of field actions converts this coherence into a population of the excited vibrational state / This is followed by yet another pair of field actions which reconvert the population into a vibrational coherence, but now one with phase opposite to the first. Now, with time, the walked-oflP component of the original coherence can reassemble into a polarization peak that produces the Raman echo at frequency oi = 2(o - (O2...

Figure Bl.3.8. A WMEL diagram for die three-colour fifth order qiiasi-Ramaii echo . As usual, the first pair of field actions creates the Raman coherence which is allowed both to dephase and walk off with time. This is followed by a second pair of field actions, which creates a different but oppositely phased Raman coherence (now hf) to the first. Its frequency is at oi - oij = Provided that frequencies are identified with an inliomogeneous distribution that is similar to those of the frequencies, then a quasi-rephasing is possible. The fifth field action converts the newly rephased Raman polarization into the quasi-echo at co = 2(b, — CO, = CO, + CO,...

Oudar J-L, Smith R W and Shen Y R 1979 Polarization-sensitive coherent anti-Stokes Raman spectroscopy Appi. Rhys. Lett. 34 758-60... 

Okamoto H and Yoshihara K 1990 Femtosecond time-resolved coherent Raman scattering under various polarization and resonance conditions J. Opt. Soc. B7 1702-8... 

Called CYCLCROP (cyclic cross polarization) [24], the method works by first exciting all magnetization. Cross polarization pulses are then applied at the specific Lannor frequencies of the H- C pair of interest so as to transfer coherence from to C. The transfer pulses must satisfy the Hartmaim-Halm condition... 

An alternative approach to obtaining microwave spectroscopy is Fourier transfonn microwave (FTMW) spectroscopy in a molecular beam [10], This may be considered as the microwave analogue of Fourier transfonn NMR spectroscopy. The molecular beam passes into a Fabry-Perot cavity, where it is subjected to a short microwave pulse (of a few milliseconds duration). This creates a macroscopic polarization of the molecules. After the microwave pulse, the time-domain signal due to coherent emission by the polarized molecules is detected and Fourier transfonned to obtain the microwave spectmm. 

The importance of laser light, in brief, is tliat its base characteristics, coherence, spectral and polarization purity, and high brilliance allow us to manipulate its properties. Gain switching [i, 10] and mode locking [16] are prime examples of our ability to very specifically control tire laser output. It is easy to see why lasers are tire ideal sources for optoelectronic applications. 

Calculations within tire framework of a reaction coordinate degrees of freedom coupled to a batli of oscillators (solvent) suggest tliat coherent oscillations in the electronic-state populations of an electron-transfer reaction in a polar solvent can be induced by subjecting tire system to a sequence of monocliromatic laser pulses on tire picosecond time scale. The ability to tailor electron transfer by such light fields is an ongoing area of interest [511 (figure C3.2.14). 

From these relations it follows that is related to the angular momentum modulus, and that the pairs of angle a, P and y, 8 are the azimuthal, and the polar angle of the (J ) and the (L ) vector, respectively. The angle is associated with the relative orientation of the body-fixed and space-fixed coordinate frames. The probability to find the particular rotational state IMK) in the coherent state is... 

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