Transient optical polarization response of aluminium at an interband transition

Wilks, Richard J.; Hicken, R. J.

doi:10.1088/0953-8984/16/25/018

Cited by 23 publications

(19 citation statements)

References 16 publications

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“…It seems natural to attribute the ultrafast part of the signal to the nonlinear-optical Kerr effect in the Co nanodots, as free electrons there can exhibit very short response times, down to a few femtoseconds. It is generally believed that in transition metals, both interband and intraband transitions contribute to the ultrafast Kerr effect [32,33]. On this timescale the nanodots act as independent light absorbers.…”

Section: (B) Illustrates the 180mentioning

confidence: 99%

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Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

et al. 2014

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Using pump-probe optical polarimetry we demonstrate that femtosecond laser excitation of a 2D regular lattice of magnetic nanodots effectively changes the optical anisotropy of the array. Study of the dynamics of the femtosecond laser-induced anisotropy reveals four main mechanisms occurring in the electronic, spin, and lattice subsystems. Below 1 ps, a strong Kerr-like nonlinearity causes linear birefringence, with its axis directed along the electric field of the linearly polarized femtosecond laser pump pulse. In addition, a long-living linear birefringence is also induced due to slowly relaxing excitations. Also below 1 ps, ultrafast laser-induced demagnetization of Co leads to a partial breakdown of the circular birefringence of the magnetic nanodots. On the timescale up to 300 ps, optically triggered acoustic modes of the dots drive oscillations of the linear optical birefringence. During this process, the oscillations damp while transferring their energy into acoustic modes of the substrate. On the nanosecond timescale, the signal is dominated by acoustic oscillations at the surface of the substrate.

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Section: (B) Illustrates the 180mentioning

confidence: 99%

“…[33], a Kerr-induced polarization rotation of a linearly polarized probe beam in the case of a linearly polarized pump beam is given by…”

Section: (B) Illustrates the 180mentioning

confidence: 99%

Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

et al. 2014

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“…The peak is associated with the transient linear dichroism induced by the pump pulse. 29 The signal contains oscillations that sit on top of the multiexponential shape. The frequency and amplitude of the oscillations appear to be independent of the pump helicity.…”

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confidence: 99%

Optical excitation of a coherent transverse optical phonon in a polycrystalline Zr metal film

et al. 2007

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Optical pump-probe measurements of transient reflectivity were made on a sputtered polycrystalline thin film of hcp Zr. On top of a slow multiexponential decay, an oscillatory signal was observed with frequency varying from the initial value of f 0 = 2.24± 0.06 THz at zero time delay to a value of 2.56± 0.12 THz after 2 ps, which is similar to that of a transverse optical ͑TO͒ phonon near the ⌫ point of the Brillouin zone. From the data, the TO phonon relaxation time was determined to be 0.67 ps. The excitation of the coherent phonon was identified as being mediated by resonant coherent Raman scattering. DOI: 10.1103/PhysRevB.76.012301 PACS number͑s͒: 78.47.ϩp, 63.20.Ϫe, 78.20.Ϫe Recently, much attention has been drawn to the study of terahertz phonons in semiconductors, semimetals, and metals. The motivation for these studies arises from the need for efficient means by which to quantify the elastic properties of solids, on one hand, and to analyze the integrity of nanoscale structures, on the other. Atomic dynamics determines new phase formation in solids and the kinetics of chemical reactions. The latest advances in ultrafast laser technology have allowed the subpicosecond nonequilibrium dynamics of phonons to be investigated in the time domain. In most of these studies, acoustic modes were investigated. In such modes, neighboring atoms oscillate in phase, and so the characteristic length scale for associated nonuniformities is given by the phonon wavelength. At the same time, in crystals with two ͑or more͒ atoms in the unit cell, there also exist optical phonons. For these modes, the two basis atoms oscillate out of phase, and so by studying optical phonons, one may obtain information about interactions on the atomic length scale, even if the phonon wavelength is not small.In striking contrast to semiconductors and semimetals, 6 there have only been a few reports of the observation of coherent optical phonons by optical pump-probe measurements in metals. 12,13,17,21,25 The observation of coherent longitudinal optical ͑LO͒ phonons in Gd was reported in Refs. 12, 13, 21, and 25. Coherent transverse optical ͑TO͒ phonons in Zn and Cd were observed in Ref. 17. The samples in those studies were single crystals. At the same time, many of the metallic nanostructures that are important for applications are prepared by sputtering and so are polycrystalline. Therefore, a question arises as to whether terahertz optical phonons can be excited and detected and, hence, used for characterization of polycrystalline metallic samples. In this Brief Reports, we show that coherent TO phonons near the center of the Brillouin zone can be optically excited and detected in a sputtered polycrystalline film of Zr.Measurements were performed at room temperature with 90 fs ͑full width at half maximum͒ transform limited pulses with photon energy of 1.575± 0.005 eV from a Ti:sapphire laser with 80 MHz repetition rate. The pump and probe were focused to a 15 m spot size, had energies of 2.25 and 0.04 nJ, and were incident on the sample...

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“…7 Results for the elliptically polarized pump were later given in order to analyze the data of Wilks and Hicken. 8 To apply the theories to a femtosecond pumpprobe experiment, an additional assumption had to be invoked that the signal should have the shape of the pumpprobe intensity cross correlation and the magnitude derived from the continuous wave model. 6,8 Here we explicitly include the electron momentum relaxation within the description of the shape of time-resolved SIFE and SOKE signals obtained from metallic samples.…”

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confidence: 99%

“…8 To apply the theories to a femtosecond pumpprobe experiment, an additional assumption had to be invoked that the signal should have the shape of the pumpprobe intensity cross correlation and the magnitude derived from the continuous wave model. 6,8 Here we explicitly include the electron momentum relaxation within the description of the shape of time-resolved SIFE and SOKE signals obtained from metallic samples. 9 The probability of optical absorption of a photon with energy E = ប can be described as ͐ −ϱ +ϱ N͉͑͒M͑ , + E͉͒H͑ + E͒d, where N͑͒ and H͑͒ are the total numbers of electrons and holes per unit energy at the energy level .…”

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confidence: 99%

Simple theory of hot electron dynamics observed by femtosecond ellipsometry

Kruglyak

Hicken

2006

Journal of Applied Physics

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The dynamics of the linear and angular momenta of hot electrons in metals are of key importance for the design and operation of hot electron devices such as spin and tunnel valve transistors. The corresponding relaxation times are expected to lie in the subpicosecond range and must be studied with experimental techniques of adequate (femtosecond) temporal resolution. Here we report a simple theory of the ultrafast ellipsometric response of metals after excitation with femtosecond optical pulses. Although developed in the relaxation time approximation, the theory allows electron linear and angular momentum relaxation times to be extracted.

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Transient optical polarization response of aluminium at an interband transition

Cited by 23 publications

References 16 publications

Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

Optical excitation of a coherent transverse optical phonon in a polycrystalline Zr metal film

Simple theory of hot electron dynamics observed by femtosecond ellipsometry

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