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Kukushkin Vladimir Alexeevich Education: Scope of professional interests: Professional career: Membership in professional organizations: Awards, prizes, grants: Pedagogical activities: Publications: Most significant papers and results: V.A. Kukushkin, "Indirect exciton superradiant recombination in diamond: Theory and the perspectives of observation", Journal of Luminescence, v. 138, pp. 164-169 (2013). V.A. Kukushkin, "Simulation of Ultraviolet_ and Soft X_Ray_Pulse Generation as a Result of Cooperative Recombination of Excitons in Diamond Nanocrystals Embedded in a Polymer Film", Semiconductors, v. 47, ¹. 11, pp. 1442-1446 (2013). V.A. Kukushkin, “Radiative lifetime of Wannier-Mott excitons in nanoclusters of semiconductors with direct and non-direct band structures”, Radiophysics and Quantum Electronics, v. 56, ¹. 7, pp. 1-10 (2013). V.A. Kukushkin, "Calculation of the radiative lifetime of Wannier-Mott excitons in nanoclusters", Advances in Nano Research, v. 1, ¹ 3, pp. 125-131 (2013). V.A. Kukushkin, “Intersubband Rabi Oscillations in Asymmetric Nanoheterostructures: Implications for a Tunable Continuous-Wave Source of a Far-Infrared and THz Radiation”, Journal of Nanoscience and Nanotechnology, v. 12, ¹ 6, pp. 4650-4657 (2012). A tunable continuous-wave source of a far-infrared and THz radiation based on a semiconductor nanoheterostructure with asymmetric quantum wells is suggested. It utilizes Rabi oscillations at a transition between quantum well subbands excited by external femtosecond pulses of a mid-infrared electromagnetic field. Due to quantum well broken inversion symmetry the subbands possess different average dipole moments, which enables the creation of polarization at the Rabi frequency as the subband populations change. It is shown that if this polarization is excited so that it is periodic in space, then, though being pulsed, it can produce continuous-wave output radiation. Changing the polarization space period and the time intervals between the exciting pulses, one can tune the frequency of this radiation throughout the far-infrared and THz range. In the present work a concrete multiple quantum well heterostructure design and a scheme of its space-periodic polarization are suggested. It is shown that for existing sources of mid-infrared femtosecond pulses the proposed scheme can provide a continuous-wave output power of order the power of far-infrared and THz quantum cascade lasers. Being added to the possibility of its output frequency tuning, this can make the suggested device attractive for fundamental research and various applications. V.A. Kukushkin, “Analytical description of the Stokes coherent cooperative Raman scattering by a subwavelength sample”, Journal of Modern Optics, v. 59, issue 13, pp. 1142-1148 (2012). V.A. Kukushkin, “Generation of a frequency-tunable far-infrared and terahertz radiation by optical nutations at intraband transitions in asymmetric semiconductor nanoheterostructures”, Semiconductors, v. 46, issue 12, pp. 1487-1492 (2012). V.A. Kukushkin, “Numerical simulation of a far-infrared fountain laser on modulation doped nanoheterostructures with quantum wells”, Nanotechnologies in Russia, v. 7, issues 9-10, pp. 527-530 (2012). V.A. Kukushkin, “Proposal for an unstrained nanoheterolaser generating a mainly TM-polarized radiation”, Optics Communications, v. 285, pp. 734-737 (2012). V.A. Kukushkin, “Far-Infrared Fountain Laser on Intraband Transitions in Semiconductor Nanoheterostructures”, Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, v. 6, no. 3, pp. 518–523 (2012). V.A. Kukushkin, “Theoretical analysis of quantum well fountain and Raman laser schemes for far-infrared and THz generation”, Journal of Optics, v. 13, 035001, 7 pages, (2011) V.A. Kukushkin, “Proposal for an inversionless tunable THz laser driven by room-temperature mid-infrared quantum cascade lasers", Semiconductor Science and Technology, v. 25, 125008, 8 pages (2010). V.A. Kukushkin, “Inversionless Amplification in Semiconductor Nanostructures: A Way to Create a Frequency-Tunable Laser of Far-Infrared and Terahertz Radiation”, Semiconductors, v. 44, no. 11, pp. 1435–1440 (2010). V.A. Kukushkin, "Proposal for an Inversionless Tunable Far-Infrared and THz Room-Temperature Laser on a Quantum Well Semiconductor Nanostructure”, IEEE Journal of Quantum Electronics, v. 46, no. 5, pp. 666-673 (2010). On the basis of density matrix formalism a mathematical model describing lasing in quantum well semiconductor nanostructures V.A. Kukushkin, “How to achieve lasing in a system with the strong lifetime broadening of working levels?”, Physics Letters A, v. 374, pp. 687-690 (2010). V.A. Kukushkin, “Tunable Inversionless Laser for the Far-Infrared and Terahertz Range Based on Nanoheterostructures with Quantum Wells”, Technical Physics Letters, v. 36, no. 2, pp. 96–99 (2010). V.A. Kukushkin, “Efficient Infrared–Terahertz Pulse Conversion in Waveguide Semiconductor Structures”, Semiconductors, v. 44, no. 1, pp. 106–111 (2010). V.A. Kukushkin, “Generation of Terahertz Radiation in High-Quality Diamond Samples”, Physics of the Solid State, v. 51, no. 9, pp. 1821–1827 (2009). V.A. Kukushkin, “Efficient Inversionless Amplification of Infrared Radiation Using Quantum Dots with Quasi-Discrete Energy Levels”, Journal of Experimental and Theoretical Physics, v. 109, v. 2, pp. 187–192 (2009). V.A. Kukushkin, “Quantum Dot-Based Tunable Inversionless Laser for the Far Infrared and Terahertz Ranges”, Journal of Experimental and Theoretical Physics Letters, v. 89, no. 9, pp. 437–440 (2009). V.A. Kukushkin, “Two-Color Optical and Mid-IR Quantum-Well Laser“, Bulletin of the Russian Academy of Sciences: Physics, v. 73, no. 1, pp. 101–106 (2009). V.A. Kukushkin, “Two-color interband and intraband quantum well heterolaser”, Physical Review A, v. 78, no. 3, 033838, 9 pages (2008). A method of mid-infrared (ir) (the wavelength 50 micrometers) generation at an intraband transition in interband optical (the wavelength 0.6 micrometers) semiconductor quantum well (QW) heterolasers is considered. It is based on partial inversion of the intraband transition due to the electron population of its upper level, stimulated by a strong optical field simultaneously generated in the same device. In previous studies of the problem, the inhomogeneous broadening of this transition (i.e., its frequency dependence on the electron energies in the subbands that form it) was not taken into account. As a result, mid-ir generation was possible only under the condition of total (i.e., integrated over electron energies) inversion. In the present work it is shown that the inhomogeneous broadening of the intraband transition allows one to achieve mid-ir generation when it is inverted only in a narrow spectral range containing the interval where its interaction with the mid-ir mode has resonant character. At the same time, total inversion at this transition is absent. This circumstance makes it possible to significantly (by several times in comparison with previous estimates) reduce the threshold pumping current density for the start of mid-ir generation. As a result, this value proves to be in the experimentally achievable domain even at room temperature. This allows one to hope for the practical realization of a pulsed two-color optical and mid-ir laser based on a heterostructure with just one QW, employing simple and cheap injection pumping only, and working without any cooling. V.A. Kukushkin, "Generation of THz radiation in semiconductors with cyclotron heating of heavy holes", Europhysics Letters, v. 84, pp. 60002p1-60002p6 (2008). A method of THz radiation generation in semiconductors in crossed static magnetic and alternating electric fields is considered. It is based on the inversion of the transition between heavy- and light-hole sub-bands in the THz spectral range. This inversion is created due to cyclotron frequencies of heavy and light holes being different. Under sufficiently low hole density when the hole-hole energy exchange is less efficient than the hole-lattice one, this fact leads to a situation when the resonant with heavy holes pump alternating electric field heats only the heavyhole population thereby inverting the heavy-light holes transition in a narrow spectral range. The optimal parameters of such a scheme were found and it was shown that it can operate even at room temperature (in the pulsed mode). V.A. Kukushkin, “Amplification of mid- and far-IR pulses in synchronously pumped low-dimensional heterostructures”, Quantum Electronics, v. 38, no. 10, pp. 909-916 (2008). V.A. Kukushkin, “Weak-Field Nonlinear Dynamic Conductivity in a Quantum Well with a Transverse Magnetic Field”, Journal of Experimental and Theoretical Physics Letters, v. 88, no. 2, pp. 103–106 (2008). A.V. Andrianov, V.Ya. Aleshkin, A.A. Belyanin, A.A. Dubinov, V.V. Kocharovskii,Vl.V. Kocharovskii, and V. A. Kukushkin, “Mode Locking and Efficient Generation of Pulsed Difference-Frequency Radiation in Two-Color Heterolasers”, Bulletin of the Russian Academy of Sciences: Physics, v. 72, no. 2, pp. 234–237 (2008). V. Kukushkin, “Periodic Transient Inversion at Intersubband Laser Transitions in Quantum Wells in an External Electric Field”, IEEE Transactions on Nanotechnology, v. 7, no. 3, pp. 344-350 (2008). V.A. Kukushkin, “Generation of terahertz pulses from tightly focused single near-infrared pulses in double plasmon waveguides”, Journal of the Optical Society of America B, v. 25, no. 5, pp. 818-824 (2008). V.A. Kukushkin, “Optical Rectification of Highly Focused Near-IR Pulses in the Plasmon Waveguide”, Technical Physics, v. 53, no. 10, pp. 1327–1331 (2008). A.A. Belyanin, V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, A.V. Andrianov, V.Ya. Aleshkin, and A.A. Dubinov, “Mode-Locked Dual-Wavelength Heterolasers for Terahertz Generation via Intracavity Wave Mixing”, Acta Physica Polonica A, v. 113, no. 3, pp. 869-873 (2008). V. Kukushkin, “Proposal for Room-Temperature Generation of Mid-Infrared Radiation in Near-Infrared Quantum-Well Heterolasers”, IEEE Photonics Technology Letters, v. 20, no. 7, pp. 481-483 (2008). V.A. Kukushkin, “Periodic Formation of Transient Population Inversion for Intersubband Laser Transitions in Quantum Wells”, Semiconductors, v. 42, no. 7, pp. 794–799 (2008). V.A. Kukushkin, “Generation of Mid-IR Radiation in Near-IR Semiconductor Lasers Based on Low-Dimensional Heterostructures”, Journal of Experimental and Theoretical Physics, v. 106, no. 3, pp. 450–458 (2008). V.A. Kukushkin, “Efficient amplification of mid- to far-infrared pulses due to optical pulse conversion in waveguiding quantum-well heterostructures”, Physical Review A, v. 76, 023817, 12 pages (2007). A method of efficient mid/far-infrared (IR) pulse amplification via driving optical pulse energy conversion in waveguiding quantum well (QW) heterostructures at room temperature is suggested. It is based on the optical pulse creating transient population inversion at an long-wavelength transition in the three-level scheme formed by QW levels of dimensional quantization. As a result, efficient amplification of a weak mid/far-IR pulse, propagating simultaneously with the driving one, becomes possible. The waveguide and QW heterostructure design, optimal for optical-long-wavelength pulse conversion, is proposed and shown to be much simpler than that used in quantum cascade lasers (QCLs). For the typical input peak power of the picosecond driving pulse and mid/far-IR pulse of about 100 W and 100-0.1 mW respectively the present scheme is able to produce output IR pulses with peak powers of at least several tens of W or several tens of mW in the mid- or far-IR range correspondingly, i.e., to convert an appreciable part of the optical pulse energy into the mid-IR signal. V.A. Kukushkin, V.Ya. Aleshkin, A.A. Belyanin, A.A. Dubinov, V.V. Kocharovsky, Vl.V. Kocharovsky, and M. O. Scully, “Difference-Frequency Pulse Generation in Quantum-Well Heterolasers”, Laser Physics, v. 17, no. 5, pp. 688-694 (2007). It is shown that the mid/far infrared (IR) and terahertz (THz) pulse generation via difference-frequency mixing in quantum-well (QW) dual-wavelength heterolasers can be rather efficient under mode-locking regime for one or both lasing fields even at room temperature. In such a device the long-wavelength field is produced in the process of intracavity difference-frequency mixing of two optical fields: continuous-wave (CW) and pulsed (or both pulsed), due to the resonant intersubband quantum coherence in QWs as well as due to the non-resonant second-order semiconductor bulk nonlinearity. The mode-locking regime of the optical generation allows one to enhance significantly the pulsed driving fields in comparison with those under CW operation, and, therefore, substantially increase the output difference-frequency power. Within a simple model an explicit formula for the intensity and shape of the generated IR or THz pulse is derived. It is shown that this method is capable of producing picosecond pulses at 1 GHz repetition rate with the peak power of the order of 1 W and <0.2 mW at 10 micrometers and 50 micrometers wavelengths, respectively. V.A. Kukushkin, “Efficient generation of terahertz pulses from single infrared beams in C/GaAs/C waveguiding heterostructures”, Journal of the Optical Society of America B, v. 23, no. 12, pp. 2528-2534 (2006). The difference-frequency THz pulse generation from Fourier components of a single infrared laser pulse in waveguiding heterostructures is considered. It is shown that a proper choice of the waveguide parameters allows to significantly reduce the input pulse group velocity dispersion (GVD). In result it is possible to noticeably increase the length of such devices and, consequently, the pump-THz pulse conversion efficiency by employing for their fabrication low absorbing materials with high GVD coefficients. In the present paper I analyze a particular example of such a scheme, a C/GaAs/C waveguiding heterostructure, find corresponding conversion rate and consider ways for its further improvement. V.A. Kukushkin, “Formation of cyclotron-annihilation lines in magnetized vacuum near neutron stars”, Monthly Notices of the Royal Astronomical Society, v. 368, pp. 976-984 (2006). We study the formation of absorption features, called cyclotron–annihilation lines, in spectra of neutron stars (pulsars) owing to the fundamental quantumelectrodynamic effect of one–photon pair creation in magnetized vacuum. As a result we substantiate a new method of the determination of neutron stars magnetic field B based on the evaluation of the interval between the main annihilation and the first cyclotron–annihilation absorption lines. It is found that these lines may be resolved and, consequently, the method may be applicable, if the following conditions are satisfied. 1) A –source has to be compact enough and located near a star, but not close to its magnetic poles. For instance, it may be a disc in the plane of a star magnetic equator with latitudinal angular width less than (B/4,4 1013 G)1/2 and radial extent up to 25 per cent of a star radius. 2) Magnetic field strength must lie in a certain narrow interval with the centre at _ 3–4 1012 G. The width of this interval depends on the star orientation and disc radial extend and in the most favorable case is about 50 per cent of its lower boundary. Finally, the influence of the star rotation on the application of this method is considered and new possibilities arising from forthcomingpolarization observations are briefly discussed. A.A. Belyanin, V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Photon absorption in a magnetized vacuum and formation of cyclotron-annihilation lines in gamma-emission of neutron stars”, Advances in Space Research, v. 33, pp. 620-624 (2004). V.A. Kukushkin, “Slowing down of the relaxation of high-frequency gas polarization in a constant electric field”, Optics and Spectroscopy, v. 91, no. 4, pp. 509-514 (2001). It is established that a sufficiently strong constant electric field can significantly slow down the rate of the gas high-frequency polarization relaxation connected with the resonant dipole-dipole interaction of its molecules. The corresponding reduction of the integral intermolecular Weisskopf collision cross-section is calculated with the use of the two-level approach for the description of the quantum dynamics of internal (oscillatory) degrees of freedom of molecules, whereas their translational and rotation motion was considered classically. It is shown that the effect arises due to the Stark change of the molecular dipole moments and the orientation of molecules in a constant electrical field. In result at a certain value of the latter the contributions from the constant and high-frequency molecular dipole moments into the change of the molecule density matrix after a collision significantly compensate for each other. The conditions necessary for the predicted effect observation are indicated. V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Antiferroelectric phase transition in a thermal gas and self-consistent Gibbs distribution over quasienergies”, Nonlinear Phenomena in Complex Systems, v. 4, no. 1, pp. 13-17 (2001). V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Spontaneous polarization in a gas of two-level molecules and Gibbs distribution over quasienergies”, Radiphysics and Quantum Electronics, v. 44, no. 1-2, pp. 161-175 (2001). We study the possibility of spontaneous formation of a polarization structure in a thermodynamically equilibrium gas of dipolarly interacting two-level molecules. Using the Maxwell--Bloch equations within the framework of the mean-field theory, we find that the antiferroelectric phase transition in a gas with a weak relaxation of the polarization is always a second-order transition. It is shown that if relaxation is neglected, then in the quasi-classical consideration of the translational motion of molecules in the polarization wave, the energy levels of a separate molecule coincide with its quasi-energies that are well known in quantum optics. Thus, to study the statistical properties of the antiferroelectric phase, we apply the generalized Gibbs distribution over quasi-energy states of the molecules. As a result, we determine the characteristic features and the possible parameters of the antiferroelectric state of a gas. In particular, it is found that, owing to the Doppler resonance of part of the molecules with the polarization wave, the properties of the gas antiferroelectrics behind the phase-transition point may radically differ from the properties of the conventional ferroelectrics in the Ginzburg--Landau theory. We also analyze the influence of polarization fluctuations for the case of a ferroelectric transition in a gas. V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Antiferroelectricity in a gas of two-level molecules and self-consistent Gibbs distribution over quasienergies”, Bulletin of the Russian Academy of Science: Physics, v. 64, no. 10, pp. 1643-1648 (2000). V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Coherent gaseous crystal and the antiferroelectric phase transition in isotropic gases”, Journal of Technical Physics, v. 38, no. 2, pp. 239-243 (1997). V.V. Kocharovsky, Vl.V. Kocharovsky, V.A. Kukushkin, “Meissner effect in superconducting cores of neutron stars”, Radiophysics and Quantum Electronics, v. 39, no. 1, pp.18-22 (1996). The evolution of magnetic field under the influence of proton plasma superconductivity in the core of a neutron star (pulsar) is considered. It is shown that for the magnetic fields B0 <1014 G the Meissner effect in a npe-superconductor of the second type cannot expulse the field from a star core. This means that without taking into account other expulsion mechanisms (such as floating of the Abrikosov vortexes and their pinning to the Onsager-Feynman vortexes in a superfluid interior of a rotating star) the magnetic field B0 <1014 G should be frozen in a core for a time >1010 years, i.e., during whole life of a neutron star.
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