TY  - JOUR
A1  - Gottscholl, Andreas
A1  - Wagenhöfer, Maximilian
A1  - Klimmer, Manuel
A1  - Scherbel, Selina
A1  - Kasper, Christian
A1  - Baianov, Valentin
A1  - Astakhov, Georgy V.
A1  - Dyakonov, Vladimir
A1  - Sperlich, Andreas
T1  - Superradiance of spin defects in silicon carbide for maser applications
JF  - Frontiers in Photonics
N2  - Masers as telecommunication amplifiers have been known for decades, yet their application is strongly limited due to extreme operating conditions requiring vacuum techniques and cryogenic temperatures. Recently, a new generation of masers has been invented based on optically pumped spin states in pentacene and diamond. In this study, we pave the way for masers based on spin S = 3/2 silicon vacancy (V\(_{Si}\)) defects in silicon carbide (SiC) to overcome the microwave generation threshold and discuss the advantages of this highly developed spin hosting material. To achieve population inversion, we optically pump the V\(_{Si}\) into their m\(_S\) = ±1/2 spin sub-states and additionally tune the Zeeman energy splitting by applying an external magnetic field. In this way, the prerequisites for stimulated emission by means of resonant microwaves in the 10 GHz range are fulfilled. On the way to realising a maser, we were able to systematically solve a series of subtasks that improved the underlying relevant physical parameters of the SiC samples. Among others, we investigated the pump efficiency as a function of the optical excitation wavelength and the angle between the magnetic field and the defect symmetry axis in order to boost the population inversion factor, a key figure of merit for the targeted microwave oscillator. Furthermore, we developed a high-Q sapphire microwave resonator (Q ≈ 10\(^4\)–10\(^5\)) with which we find superradiant stimulated microwave emission. In summary, SiC with optimized spin defect density and thus spin relaxation rates is well on its way of becoming a suitable maser gain material with wide-ranging applications.
KW  - stimulated emission
KW  - maser
KW  - population inversion
KW  - silicon vacancy
KW  - spin polarization
KW  - superradiance
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284698
SN  - 2673-6853
VL  - 3
ER  - 
TY  - JOUR
A1  - Astakhov, Georgy V.
A1  - Kraus, Hannes
A1  - Soltamov, V. A.
A1  - Fuchs, Franziska
A1  - Simin, Dimitrij
A1  - Sperlich, Andreas
A1  - Baranov, P. G.
A1  - Dyakonov, Vladimir
T1  - Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide
N2  - Quantum systems can provide outstanding performance in various sensing applications, ranging from bioscience to nanotechnology. Atomic-scale defects in silicon carbide are very attractive in this respect because of the technological advantages of this material and favorable optical and radio frequency spectral ranges to control these defects. We identified several, separately addressable spin-3/2 centers in the same silicon carbide crystal, which are immune to nonaxial strain fluctuations. Some of them are characterized by nearly temperature independent axial crystal fields, making these centers very attractive for vector magnetometry. Contrarily, the zero-field splitting of another center exhibits a giant thermal shift of −1.1 MHz/K at room temperature, which can be used for thermometry applications. We also discuss a synchronized composite clock exploiting spin centers with different thermal response.
KW  - condensed-matter physics
KW  - quantum physics
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113025
ER  - 
TY  - JOUR
A1  - Astakhov, Georgy V.
A1  - Fuchs, F.
A1  - Soltamov, V. A.
A1  - Väth, S.
A1  - Baranov, P. G.
A1  - Mokhov, E. N.
A1  - Dyakonov, V.
T1  - Silicon carbide light-emitting diode as a prospective room temperature source for single photons
JF  - Scientific Reports
N2  - Generation of single photons has been demonstrated in several systems. However, none of them satisfies all the conditions, e.g. room temperature functionality, telecom wavelength operation, high efficiency, as required for practical applications. Here, we report the fabrication of light-emitting diodes (LEDs) based on intrinsic defects in silicon carbide (SiC). To fabricate our devices we used a standard semiconductor manufacturing technology in combination with high-energy electron irradiation. The room temperature electroluminescence (EL) of our LEDs reveals two strong emission bands in the visible and near infrared (NIR) spectral ranges, associated with two different intrinsic defects. As these defects can potentially be generated at a low or even single defect level, our approach can be used to realize electrically driven single photon source for quantum telecommunication and information processing.
KW  - semiconductors
KW  - inorganic LEDs
KW  - quantum optics
KW  - nanophotonics
KW  - plasmonics
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96308
ER  -