All-optical scanning vector magnetometry based on fine and hyperfine interactions in spin-32\frac{3}{2} centers in silicon carbide

The possibility of using axial spin color centers with $S=3/2$, oriented along the hexagonal $c$ axis in a silicon carbide (SiC) wafer, has been demonstrated for all-optical measurement of projection of the external magnetic field coinciding with the $c$ axis of the crystal, and the polar and azimuthal angles of the external measured magnetic field at room and significantly higher temperatures. A distinctive feature of spin centers in SiC, in which optically induced spin alignment is carried out, is the presence of a unique system of spin levels in a magnetic field, caused by fine structure interaction and hyperfine interaction with the $^{29}$Si nuclei and there is a wide range of level anticrossings (LACs), leading to an exceptionally strong change in photoluminescence in the region of LAC and the dependence of the LAC spectrum on the orientation of the external measured magnetic field, which made it possible to develop the all-optical vector magnetometry method. Such measurements do not require microwave radiation, it is possible to use single spin center for the all-optical vector magnetometry. The proposed magnetometer is based on an external magnetic field cancellation scheme, which leads to a LAC spectrum observed in a zero external magnetic field, called its reference spectrum, by maintaining a local region of zero magnetic field at the site of optical excitation of spin centers. 4H-SiC plate is placed on the scanning stage of a confocal microscope inside the Helmholtz coils. Sensitivity to a constant magnetic field for $z$ component of the magnetic field ${B}_{z}$ is better than $0.1\mu$T$/\sqrt{\text{Hz}}$ in a volume of $1\times10^{-8}$mm$^{3}$ at room temperature. The sensitivity of determining the angles polar and azimuthal is determined by the sensitivity to determining the perpendicular component of the magnetic field, which is better than $5~\mu$T$/\sqrt{\text{Hz}}$

Structural And Optical Properties Of n-Type and p-Type GaAs(1−x)Bix Thin Films Grown By Molecular Beam Epitaxy On (311)B GaAs Substrates

In this paper, we report on the structural and optical properties of n-type Si-doped and p-type Be-doped GaAs(1−x)Bix thin films grown by molecular beam epitaxy on (311)B GaAs substrates with nominal Bi content x=5.4%. Similar samples without Bi were also grown for comparison purposes (n-type GaAs and p-type GaAs). X-ray diffraction, micro-Raman at room temperature, and photoluminescence (PL) measurements as a function of temperature and laser excitation power (PEXC) were performed to investigate their structural and optical properties. X-ray diffraction results revealed that the Bi incorporation in both n-type and p-type doped GaAsBi was similar, despite that the samples present remarkable differences in the number of Bi related defects, non-radiative centers and alloy disorder. Particularly, our results evidence that the Bi-related defects in n- and p-doped GaAsBi alloys have important impact on the differences of their optical properties

Investigation of the Effect of Substrate Orientation on the Structural, Electrical and Optical Properties of n-type GaAs1-xBix Layers Grown by Molecular Beam Epitaxy

Current-Voltage (I-V), Capacitance-Voltage (C-V), Deep Level Transient Spectroscopy (DLTS), Laplace DLTS, Photoluminescence (PL) and Micro-Raman techniques have been employed to investigate the effect of the orientation of the substrates on the structural, electrically and optically active defects in dilute GaAs1−xBix epilayers structures having a Bi composition x = ~5.4%, grown by Molecular Beam Epitaxy (MBE) on (100) and (311)B GaAs planes. X-ray diffraction results revealed that the in-plane strain in the Ga(As,Bi) layer of the samples grown on (100)-oriented substrate (−0.0484) is significantly larger than that of the samples grown on (311)B-oriented substrate. The substrate orientation is found to have a noticeable impact on the Bi incorporation and the electrical properties of dilute GaAsBi Schottky diodes. The I-V characteristics showed that (100) Schottky diodes exhibited a larger ideality factor and higher barrier height compared with (311)B samples. The DLTS measurements showed that the number of electrically active traps were different for the two GaAs substrate orientations. In particular, three and two electron traps are detected in samples grown on (100) and (311)B GaAs substrates, respectively, with activation energies ranging from 0.12 to 0.41 eV. Additionally, one hole trap was observed only in sample grown on (100) substrates with activation energy 0.24 eV. The observed traps with small activation energies are attributed to Bi pair defects. The photoluminescence (PL) and Raman spectra have evidenced different compressive strain which affects considerably the optical properties. Furthermore, the PL spectra were also affected by different contributions of Bi- related traps which are different for different substrate orientation in agreement with DLTS results

Model of the Method of Autonomous Navigation of Unmanned Aerial Vehicles Based on Infrared Images of the Terrain

В статье представлена описательная модель автономной навигации беспилотных летальных аппаратов по инфракрасным изображениям. Рассмотрен способ и алгоритм реализации модели автономной навигации. Получены численные оценки эффективности автономной навигации по данным многоспектральной разновременной фотографической съемки земной поверхностиThe article presents a descriptive model of autonomous navigation of unmanned aerial vehicles based on infrared images. The method and algorithm for implementing the autonomous navigation model are considered. Numerical estimates of the efficiency of autonomous navigation based on multispectral multi-time photographic survey of the Earth's surface are obtaine

Modeling of the Optimal Flight Route of Unmanned Aerial Vehicles Based on Infrared Video Navigation Data Based on the Upgraded Dijkstra Algorithm

В статье представлена модель построения оптимального маршрута полета беспилотных летательных аппаратов по данным инфракрасной видеонавигации на основе модернизированного алгоритма Дейкстры. Рассмотрен способ и алгоритм реализации модели построения оптимального маршрута полета. Получены численные оценки распределения частоты значений корреляции между опорными (эталонными) и текущими изображениями в инфракрасном диапазоне длин волн в разное время суток. Определен актуальный период времени суток для создания и дальнейшего применения опорных (эталонных) изображений с максимально длительным временем использования в течение следующих суток. Построены оптимальные маршруты с координатами опорного (эталонного) маршрута относительно времени формирования опорного маршрута с учетом распознавания зон блокирования полетов беспилотных летательных аппаратов по алгоритму ДейкстрыThe article presents a model for constructing the optimal flight route of unmanned aerial vehicles based on infrared video navigation data based on the upgraded Dijkstra algorithm. The method and algorithm for implementing the model for constructing the optimal flight route are considered. Numerical estimates of the frequency distribution of correlation values between reference (reference) and current images in the infrared wavelength range at different times of the day are obtained. The actual time period of the day is determined for the creation and further use of reference (reference) images with the longest possible use time during the next day. Optimal routes are constructed with the coordinates of the reference (reference) route, relative to the time of the formation of the reference route, taking into account the recognition of the zones of blocking flights of unmanned aerial vehicles according to the Dijkstra algorith