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Quantum interference control of current in bulk semiconductors is analyzed using a simple three-band model. Universal scaling rules and polarization dependence are analytically derived.
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... interference control QUIC of current in semiconductors is a subject of current interest dealing with the manipulation of the magnitude and the direction of a photo-current. 1–4 It is an example of a class of phenomena involving quantum interference between optical transitions that have been studied in atomic media. 5–7 In all cases, interference between single-photon absorption ͑ SPA ͒ and two- photon absorption ͑ TPA ͒ produces directional photoelectrons in the continuum of conduction band states. The directional- ity of the photogenerated electrons results from the fact that the two pairs of initial and final states involved in the single- and two-photon transitions are degenerate but contain different parity. Device applications based on QUIC in semiconductors have now been proposed, including the generation of short ͑ single cycle ͒ bursts of terahertz frequency radiation. 3,8,9 A calculation of the QUIC current density tensor J i jkl in bulk semiconductors was given by Atanasov et al. 4 for GaAs using a numerical model which uses a full band structure of GaAs within the local density approximation. Khurgin 8 em- ployed a simple parabolic band structure to show that QUIC and third-order optical rectification are the ‘‘real’’ and ‘‘vir- tual’’ manifestations of the same nonlinear process. In this paper, a three-band model will be presented that, in analyti- cal form, describes the QUIC scaling as well as its polarization dependence. Simple theoretical models leading to ana- lytical solutions allow for a generality that is descriptive of a large class of materials. A simple model also provides a clear physical picture that is often difficult to extract from numerical treatments. The system studied here is a zinc-blende semiconductor characterized by a conduction band and two valence bands in Kane’s theory. 10 The two valence bands are a heavy-hole ͑ hh ͒ and a light-hole ͑ lh ͒ band as depicted in Fig. 1. The starting formalism is described in Refs. 11 and 12 where initial ͑ valence ͒ and final ͑ conduction ͒ states are taken as dressed Bloch functions where the acceleration of the electrons and holes are taken into account by considering the first order ͑ i.e., time-dependent ͒ Stark shift of the energy states due to the applied ...
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Citations
... where I ω and I 2ω describe the intensities of the ω and 2ω components of the incident light [8,27]. Our sample is a 630 µm thick LT-InGaAs substrate [ Fig. 5 (a): BATOP GmbH, bPCA-100-05-10-1060-0]. ...
A single-cycle light source in the near infrared is demonstrated enabling sensitive applications of ultrafast optical field control of electronic transport. The compact Er:fiber system generates passively phase-locked pulses with broadband spectra covering 150 THz to 350 THz at a duration of 4.2 fs and 40 MHz repetition rate. A second output arm is equipped with an electro-optic modulator (EOM) that switches the arrival time of the pulses by 700 ps at arbitrary frequencies up to 20 MHz, enabling timing modulation of the pump pulse without changing the average intensity. As a benchmark demonstration, we investigate the carrier relaxation dynamics in low-temperature-grown InGaAs (LT-InGaAs) using quantum interference currents (QuICs).
... In addition, quantum interference of oneand two-photon resonant absorption pathways enables all-optical injection of ballistic charge and spin currents in bulk [10][11][12] and lowdimensional [13][14][15] semiconductors. Together with coherent control of molecular anisotropies [16], all those examples are governed by the resulting polar asymmetry in the envelope of the hybrid pulse [13,[17][18][19][20]. On the other hand, non-perturbative light-matter interactions in attosecond [21][22][23] or solid-state [24] physics require asymmetry on sub-cycle timescales which can also be accomplished via harmonic synthesis [9,25,26]. ...
We demonstrate synthesis of super-octave-spanning and phase-locked transients
in the multi-terahertz frequency range with amplitudes exceeding 13 MV/cm.
Sub-cycle polar asymmetry of the electric field is adjusted by changing the
relative phase between superposed fundamental and second harmonic components.
The resultant broken symmetry of the field profile is directly resolved via
ultrabroadband electro-optic sampling. Access to such waveforms provides a
direct route for control of low-energy degrees of freedom in condensed matter
as well as non-perturbative light-matter interactions.
... For example, such a long high precision stage as in the prototype setup is not necessary; a much cheaper piezo stage with a travel range of a few tens of micrometers corresponding to the pulse duration should be sufficient. Choosing appropriate semiconductors for current injection with another band gap than GaAs [108], could extend the method to other optical wavelengths ranges. ...
This thesis gives new insights into the physics and practical applications of coherently controlled current injection (QUIC) in the prototypical direct band gap semiconductor GaAs. QUIC is a nonlinear optical process that allows to inject electrical currents into solids by all-optical means using two-color laser pulse pairs. The direction of the induced current can be controlled by the relative phase of the pulses. Theoretical calculations predict significant deviations from the original perturbative description of QUIC at elevated excitation intensities. The first part of the thesis presents a collaborative experimental and theoretical study of this regime. In the second part it is demonstrated that QUIC can be utilized to characterize the temporal profile of ultrashort laser pulses. The last part of this thesis discusses the experimental implementation of a proposed QUIC-based current detection scheme.
... at different wavevectors. 25,26 The carrier distributions due to 2PA and 1PA at 2ω have been previously calculated. 11 Here we present the result of the ERS contribution and its interference with 1PA at ω. ...
We consider quantum interference effects in carrier and photocurrent
excitation in graphene using coherent electromagnetic field components at
frequencies and . The response of the material at the
fundamental frequency is presented, and it is shown that one-photon
absorption at interferes with stimulated electronic Raman scattering
(combined absorption and emission) to result in a net
contribution to the current injection. This interference occurs with a net
energy absorption of and exists in addition to the previously
studied interference occurring with a net energy absorption of
under the same irradiation conditions. Due to the absence of a bandgap and the
possibility to block photon absorption by tuning the Fermi level, graphene is
the perfect material to study this contribution. We calculate the polarization
dependence of this all-optical effect for intrinsic graphene and show that the
combined response of the material at both and leads to an
anisotropic photocurrent injection, whereas the magnitude of the injection
current in doped graphene, when transitions at are Pauli blocked, is
isotropic. By considering the contribution to coherent current control from
stimulated electronic Raman scattering, we find that graphene offers tunable,
polarization sensitive applications. Coherent control due to the interference
of stimulated electronic Raman scattering and linear absorption is relevant not
only for graphene but also for narrow-gap semiconductors, topological
insulators, and metals.
... Therefore, an asymmetric optical transition process in k space is essential. The optical quantuminterference process QUIC between one-and two-photon absorption is such a process, which has been used to inject charge current and spin current [17][18][19][20][21][22][23]. And as a detection technique, the Faraday rotation in QUIC has also been proposed to detect the amplitude and direction of the spin current [24]. ...
... To reveal the relation between the electron distribution function and the QUIC-AB, we calculate the transition rate of QUIC using the Volkow-type wave function [22][23][24]. In optical QUIC, the total vector potential of ω and 2ω laser pulse is given by A = a 1 A 1 cos(ωt + ϕ 1 ) + a 2 A 2 cos(2ωt + ϕ 2 ). ...
The two-color optical coherence absorption spectrum (QUIC-AB) of semiconductors in the presence of a charge current is investigated. We find that the QUIC-AB depends strongly not only on the amplitude of the electron current but also on the direction of the electron current. Thus, the amplitude and the angular distribution of current in semiconductors can be detected directly in real time with the QUIC-AB.
... In recent years, induced by harmonically related twocolor light beams with ω below and 2ω above the bandgap, the so-called "injection current" has been predicted [1][2][3] and observed [4,5] in semiconductors. It is known as the quantum interference in the oneand two-photon absorption processes (SPA and TPA) [1][2][3][4][5] and has been shown to be a resonanceenhanced third-order nonlinear process [4,6]. ...
... In recent years, induced by harmonically related twocolor light beams with ω below and 2ω above the bandgap, the so-called "injection current" has been predicted [1][2][3] and observed [4,5] in semiconductors. It is known as the quantum interference in the oneand two-photon absorption processes (SPA and TPA) [1][2][3][4][5] and has been shown to be a resonanceenhanced third-order nonlinear process [4,6]. As this current occurs on the timescale of the duration of the femtosecond laser pulse, this process can generate electromagnetic radiation at terahertz frequencies. ...
... It provides a convenient way to research the fast dynamics of carriers in semiconductors and can be used as a coherently controlled broadband terahertz source. However, the current injection efficiency is predicted to sharply decrease with increasing bandgap [3,10]. That is, wide bandgap materials are not suggested for terahertz generation using this concept. ...
We have observed terahertz generation via injection current induced by harmonically related two-color beams in an unbiased ZnSe bulk at room temperature using a femtosecond Ti:sapphire oscillator. The terahertz intensity is just several times smaller than that obtained via optical rectification and further enhancements are believed possible. Experimental results demonstrate that the terahertz radiation is mainly attributed to the transition from the split-off band. This conclusion provides a novel approach to effectively generate a broadband and coherently controlled terahertz radiation, which leads to practical applications of terahertz radiation via this mechanism.
... The angular dependences of these factors yield different results on integration depending on the specifics of the bands considered. However, a total contribution from heavy-hole and light-hole bands can be calculated for degenerate 2PA [30] and the results were shown to better match the experimental data. ...
The strive for efficiency in the generation of terahertz (THz) waves motivates intense research on novel field–matter interactions. Presently, THz generation via quadratic crystals remains the benchmark thanks to its simple and practical deployment. An interesting problem is whether new mechanisms can be exploited to elicit novel generation approaches and forms of control on the THz output in existing systems. THz generation via quantum interference (QI) leverages a third‐order nonlinear response under resonant absorption, and it has been recently explored to access surface generation in centrosymmetric systems. Its deployment in standard THz quadratic sources can potentially create a physical setting with the concurrence of two different mechanisms. Here, THz generation via QI in noncentrosymmetric crystals concurrent with phase‐matched quadratic generation in a bulk‐transmission setting is demonstrated. Beyond investigating a new physical setting, it is demonstrated that conversion efficiencies much larger than those typically associated with the medium become accessible for a typically adopted crystal, ZnTe. An inherent control on the relative amplitude and sign of the two generated THz components is also achieved. This approach provides disruptive boost and management of the optical‐to‐THz conversion performance of a well‐established technology, with significant ramifications in emerging spectroscopy and imaging applications.
