Real-space imaging of transient carrier dynamics by nanoscale pump–probe microscopy

Terada, Yasuhiko; Yoshida, Shoji; Takeuchi, Osamu; Shigekawa, Hidemi

doi:10.1038/nphoton.2010.235

Cited by 208 publications

(219 citation statements)

References 29 publications

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“…This light source with arbitrary waveform control at the nanoscale is of a fundamentally new quality compared to both conventional far-and near-field sources. It allows for the systematic extension of near background-free scanning probe microscopy [22,26,30] to the nanoscale implementation of many forms of nonlinear and ultrafast spectroscopies for spatio-temporal imaging [31].…”

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confidence: 99%

Femtosecond Nanofocusing with Full Optical Waveform Control

et al. 2011

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The spatial confinement and temporal control of an optical excitation on nanometer length scales and femtosecond time scales has been a long-standing challenge in optics. It would provide spectroscopic access to the elementary optical excitations in matter on their natural length and time scales [1] and enable applications from ultrafast nano-opto-electronics to single molecule quantum coherent control [2]. Previous approaches have largely focused on using surface plasmon polariton (SPP) resonant nanostructures [3] or SPP waveguides [4, 5] to generate nanometer localized excitations. However, these implementations generally suffer from mode mismatch [6] between the far-field propagating light and the near-field confinement. In addition, the spatial localization in itself may depend on the spectral phase and amplitude of the driving laser pulse thus limiting the degrees of freedom available to independently control the nano-optical waveform. Here we utilize femtosecond broadband SPP coupling, by laterally chirped fan gratings, onto the shaft of a monolithic noble metal tip, leading to adiabatic SPP compression and localization at the tip apex [7, 8]. In combination with spectral pulse shaping [9, 10] with feedback on the intrinsic nonlinear response of the tip apex, we demonstrate the continuous micro-to nano-scale self-similar mode matched transformation of the propagating femtosecond SPP field into a 20 nm spatially and 16 fs temporally confined light pulse at the tip apex.Furthermore, with the essentially wavelength and phase independent 3D focusing mechanism we show the generation of arbitrary optical waveforms nanofocused at the tip. This unique femtosecond nano-torch with high nano-scale power delivery in free space and full spectral and temporal control opens the door for the extension of the powerful nonlinear and ultrafast vibrational and electronic spectroscopies to the 2 nanoscale [11, 12].In order to achieve the goal of an efficient nanometer confined femtosecond light source with independent spatial localization and temporal control of the optical field, and which can freely be manipulated in 3D, the use of the unique properties of surface plasmon polaritons (SPP's) has long been discussed as a potential solution. It is well established that the strong surface field localization and size and shape dependent resonances of SPP's as electromagnetic surface waves associated with collective charge density oscillations at noble metal-dielectric interfaces allow for sub-wavelength spatial control of even broadband optical fields [13]. Elegant solutions to overcome the SPP diffraction limit [14] and achieve nano-focusing based on interference of localized SPP modes exist in the form of specially arranged cascaded, percolated, or self-similar chains of metal nanostructures as optical antennas [3,15,16]. However, the achievable optical waveforms at the nano-focus are often constrained by the phase relationship between the spectral modes already necessary to achieve the 3D nano-focusing [5]. This limits ...

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Femtosecond Nanofocusing with Full Optical Waveform Control

et al. 2011

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“…Knowledge of the pulse profile reaching the tunnel junction is applied to optimize the experiment's time response by actively shaping the incident pulses. Scanning probe microscope studies focus increasingly on measuring fast time-dependent processes at atomic dimensions, such as spin [1][2][3][4] and charge 5,6 dynamics or molecular motion. [7][8][9][10] Heterodyne frequency mixing 11 and pump-probe excitation schemes 2,[12][13][14][15] have been put forward as techniques to measure repetitive variations of the tunnel current in a scanning tunneling microscope (STM).…”

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Quantitative mapping of fast voltage pulses in tunnel junctions by plasmonic luminescence

Große

Etzkorn

Kuhnke

et al. 2013

Applied Physics Letters

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“…We believe that it is possible to perform this experiment with present day technology because latest ad-vances in ultrafast pump-probe techniques enable to measure the transients down to femtosecond timescale 27,28 . The entire set-up shown in Fig.1 is kept in a dilution refrigerator in order to access the ambient temperatures around T K .…”

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Transient thermoelectricity in a vibrating quantum dot in Kondo regime

Goker¹,

Uyanik²

2012

Physics Letters A

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We investigate the time evolution of the thermopower in a vibrating quantum dot suddenly shifted into the Kondo regime via a gate voltage by adopting the time-dependent non-crossing approximation and linear response Onsager relations. Behaviour of the instantaneous thermopower is studied for a range of temperatures both in zero and strong electron-phonon coupling. We argue that inverse of the saturation value of decay time of thermopower to its steady state value might be an alternative tool in determination of the Kondo temperature and the value of the electron-phonon coupling strength. Keywords: A. Quantum dots; D. TunnelingInvestigation of time-dependent electron transport in single electron transistors has gained considerable traction lately as a result of tremendous advances in the burgeoning field of nanotechnology and their perceived potential to replace MOSFET transistors 1 one day. Development of quantum computers 2 and single electron guns 3 are expected to benefit from advances in detection of electrons in real time too 4 .Transient current ensuing after sudden shifting of the gate or bias voltage 5,6,8 displays different time scales 9,10 . For an asymmetrically coupled system, interference between the Kondo resonance and the sharp features in the contacts' density of states gives rise to oscillations in the long time scale 11 . Modeling the contacts' density of states in a realistic fashion via ab initio calculations yielded accurate predictions about transient current 12,13 .Measurement of thermopower (Seebeck coefficient) S can provide additional insight into transport experiments because its sign is a valuable tool to determine the alignment of orbitals of the impurity with respect to the Fermi levels of the contacts. To this end, significant progress has been achieved in performing thermoelectric measurements in molecular junctions [14][15][16][17] .Theoretical studies focused on incorporating strong correlation effects into this prototype. Kondo effect, arising from a hybridization between the net spin localized within the impurity and the electrons in the contacts, is a prime example of strong electronic correlations. Schemes employing Ng's ansatz 18 and Wilson's numerical renormalization group 19 both found that the sign of the thermopower can be adjusted by tuning the energy level of the quantum dot in the presence of Kondo correlations. When the electrodes are ferromagnetic, it was found that the thermopower is suppressed at low temperatures in parallel configuration and asymmetrically coupled antiparallel configuration 20 .Nevertheless, all of the aforementioned studies only took into account the steady state behaviour of thermoelectric transport and there was very little understanding of the temporal evolution of thermopower until now. Indeed, a recent work made the first attempt to elucidate the time-dependent behaviour of the Seebeck coefficient for a noninteracting system 21 . In this paper, we will take a step forward and study the transient response of thermopower for an interacting q...

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Real-space imaging of transient carrier dynamics by nanoscale pump–probe microscopy

Cited by 208 publications

References 29 publications

Femtosecond Nanofocusing with Full Optical Waveform Control

Femtosecond Nanofocusing with Full Optical Waveform Control

Quantitative mapping of fast voltage pulses in tunnel junctions by plasmonic luminescence

Transient thermoelectricity in a vibrating quantum dot in Kondo regime

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