Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Lithuanian Journal of Physics

Generation of THz-radiation by difference-frequency mixing at one- and two-photon resonances

E. Gaižauskas, Ona Balachninaitė, Oleg Kh Khasanov

Published Oct 21, 2014• 1 citation
Publisher

Abstract

In this work, difference-frequency generation is theoretically analysed for the three-level quantum system, having forbidden in dipole approximation electronic and optically active vibration transitions from the ground state. Excitation of coherent phonon polaritons wave in the terahertz frequency range by an ultrashort optical pulse, being in the visible or near-infrared spectral regions, and injected pulse with frequency almost twice that of the pump is considered. Dynamics of terahertz radiation arising during excitation of both electronic and vibrational coherences at the two-photon and combined resonances in the ensemble of three-level quantum systems was evaluated.

DOI
10.3952/physics.v54i3.2955

Related papers

Generation of Extremely Short Pulses of Terahertz Radiation Based on Superradiation of a Three-Level Resonant Medium

Rostislav M. Arkhipov, Nikolay N. Rosanov

Abstract The possibility of generating extremely short pulses of terahertz (THz) radiation due to superradiance—collective spontaneous emission of a thin layer of a three-level resonant medium excited by a pair of attosecond (or femtosecond) pulses—is studied theoretically. The source of a terahertz pulse is a pulse of stopped nonlinear polarization of the medium, which arises in the interval between its excitation and deexcitation. The case of a three-level medium with equidistant energy levels (as in a quantum harmonic oscillator) the transition frequency of which lies in the THz range is considered. The influence of the populations of the excited levels of the medium on the shape of a terahertz superradiance pulse is discussed.

Optics and Spectroscopy•Mar 1, 2021•4 citations

Theory of Optical Frequency Mixing Using Resonant Phenomena

Ali Javan, A. Szöke

The nonlinear interaction of two intense optical waves with three energy levels of an atomic system is analyzed theoretically. The frequencies of the applied fields are assumed to be on or near two of the resonances involving the three levels. Particular attention is given to the generation of power at the difference frequency of the two applied fields where their frequency separation lies in the far-infrared range of the spectrum. In the limit of large input fields where atomic transitions are driven to saturation, the generated difference-frequency power is no longer proportional to the product of the two input powers. It is shown that, in this limit, the total rate of emission of photons at the difference frequency may, in principle, approach a value given by $\frac{\mathrm{rN}}{T}$, where $N$ is the total number of atoms, $T$ is the average time of coherent interaction of atoms and the radiation field, and $r$ is a factor which in favorable cases approaches unity at low temperatures. Also, a number of additional effects are encountered due to coherent double-quantum transitions among various levels which may be ignored only for weak input powers. These effects are highly dependent on the modes of relaxations of atomic levels and the details of the line shape. The results are applied to several cases, in which the resonance condition yields large efficiency in nonlinear frequency mixing.

Physical Review•Jan 18, 1965•15 citations

Coherent Generation of Short Terahertz Pulses in Doped Optical Crystals

Elena A. Kuznetsova, Yuri V. Rostovtsev, Nikolai G. Kalugin +3 more

Terahertz radiation has unique potential for applications to material diagnostics including semiconductors, chemical compounds, biomolecules and biotissues, imaging for medical and security applications, remote atmospheric sensing and monitoring, astronomy, etc. The search for efficient, high-power, inexpensive, portable and room temperature suitable methods of generation of THz radiation is one of the main topics in modern optoelectronics and photonics. Specifically, coherent solid-state compact efficient THz sources are desirable. Recently we suggested a new approach to the problem of generation of short coherent THz pulses in molecular gases taking advantage of the dramatic enhancement of a nonlinear response of a medium via quantum coherence. Stimulated Raman adiabatic passage (STIRAP) technique was proposed for preparation of maximal molecular coherence by two optical pump fields, which is further used to efficiently scatter off an IR probe beam and generate a Stokes THz field in a double Λ scheme. The central idea of the crystal-based technique is to generate THz radiation by resonantly inducing coherence at the corresponding transition by coherent optical fields. Electronic levels of the THz transition are coupled by a pair of optical fields to a common ground state forming a V scheme of energy levels. Coherence induced by the optical fields at the THz transition gives rise to polarization provided that the corresponding dipole moment is not zero, which will radiate out a THz pulse. We show that coherently driven molecular (such as methanol, H2F2, CH3Cl, etc.) and solid-state (ruby, alexandrite) media can potentially produce strong, controllable, short pulses of THz radiation. The pulses have energies ranging from hundreds pJ to J and time durations from several fs to ns at room temperature.

Frontiers in Optics•Jan 1, 2006•0 citations

Probing electronic coherences by combined two- and one-photon excitation in atomic vapors

E. Gaižauskas, Dionysios Pentaris, Thomas Efthimiopoulos +1 more

Wave mixing in a three-level quantum system induced by two-photon resonant pump and one-photon resonant coupling at lower transition has been studied theoretically and experimentally. Resonantly enhanced difference-frequency generation efficiency was observed clearly dependent on the time delay and its sign between the femtosecond pump and probe. The role of the atomic coherences on the amplification without inversion during different sequences of interaction in a closed three-level system has been also stressed. These findings were confirmed experimentally in atomic potassium, where strong parametric amplification, induced by the pump delayed with respect to the probe, has been observed for the first time.

Optics Letters•Jan 8, 2013•17 citations

Generation of continuous-wave terahertz radiation by use of quantum interference

Eugeny Korsunsky, Dmitry V. Kosachiov

We propose a scheme for the generation of continuous-wave terahertz (THz) radiation. The scheme requires a medium in which three discrete states in a Λ configuration can be selected, with the THz frequency transition being between the two lower metastable states. The propagation of three-frequency continuous-wave electromagnetic (EM) radiation through a Λ medium is considered. Under resonant excitation, the medium absorption can be strongly reduced owing to quantum interference of transitions, whereas the nonlinear susceptibility is enhanced. This leads to efficient energy transfer among the EM waves, providing the possibility of THz generation. We demonstrate that the photon conversion efficiency is approaching unity in this technique.

arXiv:quant-ph/9912062•Journal of the Optical Society of America B•Aug 1, 2000•11 citations

Генерация предельно коротких импульсов терагерцового излучения на основе сверхизлучения трехуровневой резонансной среды

Р. М. Архипов, Н.Н. Розанов

The possibility of generating extremely short pulses of terahertz (THz) radiation due to superradiance - collective spontaneous emission of stopped polarization of a thin layer of a three-level resonant medium excited by a pair of attosecond (or femtosecond) pulses is studied theoretically. The source of a terahertz pulse is a pulse of stopped nonlinear polarization of the medium, which occurs in the interval between its excitation and de-excitation. The case of a three-level medium with equidistant energy levels (as in a quantum harmonic oscillator), the transition frequency of which lies in the THz range, is considered. The influence of the populations of the excited levels of the medium on the shape of the terahertz superradiance pulse is discussed.

Оптика и спектроскопия•Jan 1, 2021•0 citations
In this work, difference-frequency generation is theoretically analysed for the three-level quantum system, having forbidden in dipole approximation electronic and optically active vibration transitions from the ground state. Excitation of coherent phonon polaritons wave in the terahertz frequency range by an ultrashort optical pulse, being in the visible or near-infrared spectral regions, and injected pulse with frequency almost twice that of the pump is considered. Dynamics of terahertz radiation arising during excitation of both electronic and vibrational coherences at the two-photon and combined resonances in the ensemble of three-level quantum systems was evaluated.
Abstract The possibility of generating extremely short pulses of terahertz (THz) radiation due to superradiance—collective spontaneous emission of a thin layer of a three-level resonant medium excited by a pair of attosecond (or femtosecond) pulses—is studied theoretically. The source of a terahertz pulse is a pulse of stopped nonlinear polarization of the medium, which arises in the interval between its excitation and deexcitation. The case of a three-level medium with equidistant energy levels (as in a quantum harmonic oscillator) the transition frequency of which lies in the THz range is considered. The influence of the populations of the excited levels of the medium on the shape of a terahertz superradiance pulse is discussed.
The nonlinear interaction of two intense optical waves with three energy levels of an atomic system is analyzed theoretically. The frequencies of the applied fields are assumed to be on or near two of the resonances involving the three levels. Particular attention is given to the generation of power at the difference frequency of the two applied fields where their frequency separation lies in the far-infrared range of the spectrum. In the limit of large input fields where atomic transitions are driven to saturation, the generated difference-frequency power is no longer proportional to the product of the two input powers. It is shown that, in this limit, the total rate of emission of photons at the difference frequency may, in principle, approach a value given by rNT\frac{\mathrm{rN}}{T}TrN​, where NNN is the total number of atoms, TTT is the average time of coherent interaction of atoms and the radiation field, and rrr is a factor which in favorable cases approaches unity at low temperatures. Also, a number of additional effects are encountered due to coherent double-quantum transitions among various levels which may be ignored only for weak input powers. These effects are highly dependent on the modes of relaxations of atomic levels and the details of the line shape. The results are applied to several cases, in which the resonance condition yields large efficiency in nonlinear frequency mixing.
Terahertz radiation has unique potential for applications to material diagnostics including semiconductors, chemical compounds, biomolecules and biotissues, imaging for medical and security applications, remote atmospheric sensing and monitoring, astronomy, etc. The search for efficient, high-power, inexpensive, portable and room temperature suitable methods of generation of THz radiation is one of the main topics in modern optoelectronics and photonics. Specifically, coherent solid-state compact efficient THz sources are desirable. Recently we suggested a new approach to the problem of generation of short coherent THz pulses in molecular gases taking advantage of the dramatic enhancement of a nonlinear response of a medium via quantum coherence. Stimulated Raman adiabatic passage (STIRAP) technique was proposed for preparation of maximal molecular coherence by two optical pump fields, which is further used to efficiently scatter off an IR probe beam and generate a Stokes THz field in a double Λ scheme. The central idea of the crystal-based technique is to generate THz radiation by resonantly inducing coherence at the corresponding transition by coherent optical fields. Electronic levels of the THz transition are coupled by a pair of optical fields to a common ground state forming a V scheme of energy levels. Coherence induced by the optical fields at the THz transition gives rise to polarization provided that the corresponding dipole moment is not zero, which will radiate out a THz pulse. We show that coherently driven molecular (such as methanol, H2F2, CH3Cl, etc.) and solid-state (ruby, alexandrite) media can potentially produce strong, controllable, short pulses of THz radiation. The pulses have energies ranging from hundreds pJ to J and time durations from several fs to ns at room temperature.
Wave mixing in a three-level quantum system induced by two-photon resonant pump and one-photon resonant coupling at lower transition has been studied theoretically and experimentally. Resonantly enhanced difference-frequency generation efficiency was observed clearly dependent on the time delay and its sign between the femtosecond pump and probe. The role of the atomic coherences on the amplification without inversion during different sequences of interaction in a closed three-level system has been also stressed. These findings were confirmed experimentally in atomic potassium, where strong parametric amplification, induced by the pump delayed with respect to the probe, has been observed for the first time.
We propose a scheme for the generation of continuous-wave terahertz (THz) radiation. The scheme requires a medium in which three discrete states in a Λ configuration can be selected, with the THz frequency transition being between the two lower metastable states. The propagation of three-frequency continuous-wave electromagnetic (EM) radiation through a Λ medium is considered. Under resonant excitation, the medium absorption can be strongly reduced owing to quantum interference of transitions, whereas the nonlinear susceptibility is enhanced. This leads to efficient energy transfer among the EM waves, providing the possibility of THz generation. We demonstrate that the photon conversion efficiency is approaching unity in this technique.
The possibility of generating extremely short pulses of terahertz (THz) radiation due to superradiance - collective spontaneous emission of stopped polarization of a thin layer of a three-level resonant medium excited by a pair of attosecond (or femtosecond) pulses is studied theoretically. The source of a terahertz pulse is a pulse of stopped nonlinear polarization of the medium, which occurs in the interval between its excitation and de-excitation. The case of a three-level medium with equidistant energy levels (as in a quantum harmonic oscillator), the transition frequency of which lies in the THz range, is considered. The influence of the populations of the excited levels of the medium on the shape of the terahertz superradiance pulse is discussed.