Carbon electronics and photonics

Diamond surpasses all known semiconductors in basic parameters, second only to gallium arsenide and graphene (a quasimetallic form of carbon) in electron mobility. For a long time, the widespread use of diamond in electronics was limited by the high cost and poor quality of both natural and synthetic raw materials. Currently, the technology of synthesis and doping of diamond has reached the necessary level for the breakthrough of diamond into electronics and photonics [1, 2]. In the first place, diamond based electronic devices will ensure long term and efficient operation in high temperature conditions and high levels of ionizing radiation, in the subterahertz frequency rang

Changes in the exciton cathodoluminescence spectra of diamond at elevated temperatures

The study of exciton cathodoluminescence in diamond is not only scientific but also practical importance. Ultraviolet radiation at a wavelength of 235 nm can be used for disinfection, activation of surface reactions, photochemistry, and more. Thus, diamond is a promising material for creating a cathodoluminescent source of ultraviolet radiation

Prototype of a diamond based UV source as an emitter

The report deals with the results of a study of the exciton cathodoluminescence of diamond, as well as the creation of a prototype of a cathodoluminescent ultraviolet source based on it

Solar wind detector based on Cherenkov radiation in diamond

To date a relevant task is the development of miniature Cherenkov detectors that could be placed on microsatellites for studying near Earth space, in particular, for observing the charged particles flows (solar wind) captured by the Earth's magnetic field. Solar activity can negatively affect the exploration of outer space, in particular, lead to the failure of the electronic equipment of spacecraft, which leads to significant financial losses. Therefore, the problem of monitoring and space weather forecasting is a very important task

Excitonic absorption and emission in diamond near the edge of fundamental absorption

The study of optical absorption of CVD diamond near the fundamental absorption edge was performed in the temperature range of 87-296 K. At temperatures lower than 195 K the absorption was practically constant. At higher temperatures the sharp increase of absorption took place. This sharp increase was attributed to the sharp enrichment of the phonon spectrum. Same phonon modes have different contributions to the negative and the positive branches of freeexciton absorption. For the negative branch (phonon absorption) the TA-mode dominated. For the positive branch (phonon emission) the TO-mode dominated. The possibility of diamond-based cathodoluminescent UV-sources at 235 nm was demonstrated

Amplified spontaneous emission at nv centers in diamond under optical pumping

NV – centers in diamond – a unique quantum object, which potentially implements singlephoton sources for quantum cryptography problems, physical implementation of q-bits (quantum logic elements), magnetometric sensors, etc. [1–3]. The creation of photonic integrated circuits based on diamond involves the creation of optical analogs of elements implemented in existing integrated circuits, that is, in the process of growing a diamond processor, it is necessary to create optical fibers, splitters, interferometers and integrated laser sources. But if the creation of a passive element base based on diamond does not cause difficulties, the implementation of laser sources was hampered by the presence of two diamond charge states (NV0 and NV-). As shown by recent studies [4], the neutral charge state (NV0 – center) is a negative factor for the generation of laser radiation

Contact complete integrability

Complete integrability in a symplectic setting means the existence of a Lagrangian foliation leaf-wise preserved by the dynamics. In the paper we describe complete integrability in a contact set-up as a more subtle structure: a flag of two foliations, Legendrian and co-Legendrian, and a holonomy-invariant transverse measure of the former in the latter. This turns out to be equivalent to the existence of a canonical $\R\ltimes \R^{n-1}$ structure on the leaves of the co-Legendrian foliation. Further, the above structure implies the existence of $n$ contact fields preserving a special contact 1-form, thus providing the geometric framework and establishing equivalence with previously known definitions of contact integrability. We also show that contact completely integrable systems are solvable in quadratures. We present an example of contact complete integrability: the billiard system inside an ellipsoid in pseudo-Euclidean space, restricted to the space of oriented null geodesics. We describe a surprising acceleration mechanism for closed light-like billiard trajectories

Transient Shear Wave Propagation in a Viscoelastic Gel Cylinder: Comparison of Theory to MRI-Based Measurements

ABSTRACT Shear strain patterns in a cylindrical gelatin sample under transient angular acceleration were measured by tagged magnetic resonance imaging (MRI). Measured strain fields were compared to theoretical strain fields obtained by finite element (FE) simulation. Agreement between theory and experiment is very good. The current results support the utility of the experimental approach for tasks such as measurement of shear waves in brain tissue during angular acceleration of the skull. The results also show that a simple viscoelastic model is suitable to describe rapid shear deformation of a gel biomaterial

High-vacuum-compatible high-power Faraday isolators for gravitational-wave interferometers

Faraday isolators play a key role in the operation of large-scale gravitational-wave detectors. Second-generation gravitational-wave interferometers such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo will use high-average-power cw lasers (up to 200 W) requiring specially designed Faraday isolators that are immune to the effects resulting from the laser beam absorption–degraded isolation ratio, thermal lensing, and thermally induced beam steering. In this paper, we present a comprehensive study of Faraday isolators designed specifically for high-performance operation in high-power gravitational-wave interferometers