Surface selectivity in four-wave mixing: transient gratings as a theoretical and experimental example

Fishman, I. M.; Marshall, Christopher D.; Meth, Jeffrey S.; Fayer, M. D.

doi:10.1364/josab.8.001880

Cited by 38 publications

(19 citation statements)

References 26 publications

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“…R is proportional to the spatial average of the quasiparticle concentration, whereas TG is proportional to the component of the quasiparticle concentration at the fundamental period of the grating, λ g [15]. In Fig.…”

Section: Resultsmentioning

confidence: 99%

Recombination and propagation of quasiparticles in cuprate superconductors

Gedik

2004

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In these experiments, the nonequilibrium state is prepared by the absorption of short (less than 100 fs) laser pulses, typically in the near-infrared, that perturb the density and energy distribution of quasiparticles. The evolution of the nonequilibrium state is probed by timeresolving the changes in the optical response functions of the medium that take place after photoexcitation. Ultimately, the goal of such experiments is to understand not only the nonequilibrium state, but to shed light on the still poorly understood equilibrium properties of these materials.We report nonequilibrium experiments that have revealed aspects of the cuprates that have been inaccessible by other techniques. Namely, the diffusion and recombination coefficients of quasiparticles have been measured in both YBa 2 Cu 3 O 6.5 and Bi 2 Sr 2 CaCu 2 O 8+x 2 using time-resolved optical spectroscopy. Dependence of these measurements on doping, temperature and laser intensity is also obtained.To study the recombination of quasiparticles, we measure the change in reflectivity ∆R which is directly proportional to the nonequilibrium quasiparticle density created by the laser. From the intensity dependence, we estimate β, the inelastic scattering coefficient and γ th thermal equilibrium quasiparticle decay rate. We also present the dependence of recombination measurements on doping in Bi 2 Sr 2 CaCu 2 O 8+x . Going from underdoped to overdoped regime, the sign of ∆R changes from positive to negative right at the optimal doping. This is accompanied by a change in dynamics. The decay of ∆R stops being intensity dependent exactly at the optimal doping. We provide possible interpretations of these two observations.To study the propagation of quasiparticles, we interfered two laser pulses to introduce a spatially periodic density of quasiparticles. Probing the evolution of the initial density through space and time yielded the quasiparticle diffusion coefficient, and both inelastic and elastic scattering rates. Measured diffusion coefficient suggests that the quasiparticles induced by the laser occupy primarily states near the antinodal regions of the Brillouin zone. Professor Joseph Orenstein Dissertation Committee Chair iiiTo everyone who supported me iv

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Section: Resultsmentioning

confidence: 99%

Recombination and propagation of quasiparticles in cuprate superconductors

Gedik

2004

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“…This retains the essential features necessary for understanding the signal spatial origin without any unnecessary complexity. Thus relation (2.51) is reduced to Although this limiting case was discussed in detail previously, 28 we summarize some of the important features of vacuum-surface transient holographic diffraction here for completeness.…”

Section: Theorymentioning

confidence: 97%

“…The authors take this opportunity to correct the following typographical errors contained in a previous paper 28 :…”

Section: Appendix Amentioning

confidence: 99%

Transient grating diffraction from an interface between two materials: theory and experimental application

et al. 1993

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A general theory for transient grating diffraction from both sides of a single interface is developed. The grating is assumed to have an arbitrary amplitude on both sides of a bound interface with the grating wave vector parallel to the interface. The specific spatial origin of the diffracted light is described for both the reflected and the transmitted geometries of diffraction. In the reflected geometry the signal is dominated by diffraction from a region near the interface that is a small fraction of an optical wavelength wide. The transmitted geometry signal measures primarily the mean bulk properties of the sample. An experimental example of thermal-transient grating diffraction from a YBa 2 Cu307-, /SrTiO3 interface is presented. Model calculations for the experimental data are performed to demonstrate that the approach can be used to monitor spatially nonuniform transient grating temporal relaxation.

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“…2,3,[5][6][7][8] In most cases, the transient grating experiments have been done in the transmission diffraction geometry. Even though it is technically more challenging, the transient grating experiments can be done in the reflection diffraction geometry for probing dynamics near a surface.…”

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confidence: 99%

“…Even though it is technically more challenging, the transient grating experiments can be done in the reflection diffraction geometry for probing dynamics near a surface. 9,10 A recent paper by Fishman et al 8 has deduced that in the reflection geometry, the scattering signal is equivalent to that from a grating with a /4ͱn 2 ϩk 2 thickness, which is much shorter than the light penetration depth of /4k in most cases, and thus gives a much higher surface sensitivity ͑ is the wavelength of the scattered light͒.…”

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confidence: 99%