


Vol 38, No 6 (2017)
- Year: 2017
- Articles: 11
- URL: https://journal-vniispk.ru/1071-2836/issue/view/15494
Correction



Article
Nonnegative Discrete Symbols and Their Probabilistic Interpretation
Abstract
We review the quantizer–dequantizer formalism of constructing symbols of the density operators and quantum observables, such as Wigner functions and tomographic-probability distributions. We present a tutorial consideration of the technique of obtaining minimal sets of dequantizers (quorum) related to the observable eigenvalues for one-qubit states. We discuss a generalization of the quantizer–dequantizer scheme on the example of spin-1/2 states. We consider the possibilities of extending the results to two-qubit systems using spin tomograms of the state density matrix.



Symplectic Tomography of De Broglie Wave
Abstract
We consider tomograms and quasidistribution functions like the Wigner functions that violate the standard normalization condition and obtain the conditions under which a reconstruction of the density matrix using these tomograms and quasidistribution functions is possible. Then we study an example of the de Broglie plane wave.



Electrons in a Nonideal Partially Degenerated Plasma with Multiple Ionization
Abstract
We consider peculiarities in the behavior of free electrons in an extremely-dense hot plasma with multiple ionization and partial degeneration. In different ways, we exhibit the strong Coulomb coupling of electrons and ions in the behavior of low- and high-kinetic-energy electrons. As a result, a necessity arises to consider, along with classical fast Debye electrons, their complementary cellular group of electrons constantly interacting with central ions of cells. We discuss the distribution of free electrons between the two groups, along with the role of two-group effects, of a not point character of ions in electron-transfer processes, and the consequences of the X-ray emitting X-pinch hot spot for the plasma. The existence of the physical limits for X-pinch plasma compression is among those consequences.



Coherent Phonon-Mode Excitation in Submicron Single-Crystal Diamond Films with a Graphitized Layer Built-In
Abstract
We report the first experimental observation of high-efficient phonon-mode coherent excitation using stimulated low-frequency Raman scattering (SLFRS) in submicron diamond{graphite{diamond heterostructure films with an ion-beam-induced graphitized layer. We show that the SLFRS process in submicron diamond heterostructures has a frequency shift in the gigahertz range and estimate experimentally the SLFRS conversion efficiency and threshold.



Optimization of Diode-Pumped Continuous-Wave Tape-Casting YAG/Nd:YAG/YAG-Ceramic Lasers
Abstract
We demonstrate a diode-laser-pumped solid-state 1.06 μm laser using a novel YAG/Nd:YAG/YAG composite ceramics with a sandwich structure. We optimize the laser performance using different output couplers, pumping beam waists, and cavity lengths. A maximum CW output power of 11 W for the YAG/Nd:YAG/YAG-ceramic laser is obtained at an absorbed pump power of 25 W resulting in a slope efficiency of 49.4%. The excellent output performance shows that the novel YAG/Nd:YAG/YAGceramic material has a great potential in applications with diode-laser pumping.



Performance Analysis and Relay Location Research of OFDM Free-Space Optical Communication Systems Under Moderate and Strong Turbulence
Abstract
In this paper, based on the Gamma–Gamma channel model for describing moderate and strong atmospheric turbulence, we study the relay location of serial decode-and-forward relay systems and parallel decode-and-forward relay systems in free-space optical (FSO) communication. According to the orthogonal frequency-division multiplexing modulation (OFDM) and coherent detection demodulation technology, we develop a novel statistical fading channel model for relay FSO systems by incorporating the atmospheric turbulence, pointing errors, and path loss effects. Based on this channel model, we derive the closed-form expression of the outage probability in the FSO serial relay system and parallel relay system, using the Meijer G-function. The serial decode-and-forward relay system with different relay locations and parallel decode-and-forward relay system, which consider different number of links and different relay locations, are simulation analyzed under moderate and strong atmospheric turbulence. The performance of serial relay systems and parallel relay systems in free-space optical communication can be improved by optimizing the relay location.



Effect of Melting Times on the Down-Shifting Properties in Ce3+-Doped Oxyfluoride Glass Ceramics for a-Si Solar Cells
Abstract
We synthesize Ce3+-doped oxyfluoride glass ceramics (GCs) with different melting times employing the conventional melt-quenching method. We investigate the crystal structure and photoluminescence properties of Ce3+-doped GCs in detail in order to evaluate the effect of melting times on the downshifting properties. The photoluminescence properties revealed that the Ce3+ doped GCs have an intense emission band in the broad region from 480 to 600 nm under 427 nm excitation. We improve the energy-conversion efficiency of a-Si solar cells by 0.41%, from 5.02% to 5.43%, by incorporating the Ce3+-doped GCs with a melting time of 1.5 h. The above results indicate that Ce3+-doped GCs can be a promising candidate as downshifting materials for applications in a-Si solar cells.



High-Power Diode-End-Pumped Slab Composite Tm:YLF Compact Laser
Abstract
We design a continuous-wave Tm:YLF laser with a composite slab crystal end-pumped by two fiber-coupled laser diodes at room temperature. We achieve a maximum continuous wave output power of 105 W for the bonded slab Tm:YLF laser; the corresponding slope efficiency is 47.7% and the optical-to-optical conversion efficiency is 42.0% with respect to the incident pump power. The laser operated at 1,907.5 nm with a beam quality factor of M2∼3.2 at the highest output power.



Repetition Operation of A 447.3 nm Blue–Violet Laser by Intracavity Frequency Doubling of an LD-Pumped Cesium Vapor Laser
Abstract
We investigate experimentally the repetition operation of a 447.3 nm blue–violet lasers pumped by intracavity frequency doubling of an LD-pumped cesium vapor laser. We study the output performance of the 447.3 nm laser using am LBO crystal as an intracavity frequency doubler. We obtain maximum power in the repetition operation of 0.36 mW, and the slope efficiency does not decrease in the range of pump powers from 2 to 16 W. Our results show that the thermal effect can be reduced in the repetition operation. The optimized working temperature of the LBO is ~25°C, with a full width at half maximum (FWHM) of 4.1°C.



A Tm:YLF End-Pumped Acousto-Optic Q-Switched Ho:YAG Laser
Abstract
We report an acoustic Q-switched Ho:YAG laser end-pumped by a 1,908 nm Tm:YLF laser. The doping concentration of Ho:YAG crystal is 2 at.%, and dimensions ø5×20 mm. We measure the pulsedlaser output characteristics of the Ho:YAG laser at different repetition rates (RF). Under optimum experimental conditions, the high-power 2.1 μm output power reaches 4.17 W at a given pump power of 13.25 W and repetition frequency of 8.0 kHz. For a slope efficiency of 16.88%, the corresponding optical-to-optical conversion efficiency reaches 31.47%. We obtain a minimum single pulsed energy of 7.36 mJ and a pulse width of 52.8 ns at a pump power of 10.52 W and repetition rate of 0.5 kHz, with a peak power of 139 kW.


