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Emission of Terahertz Electromagnetic Radiation

#4049


Emission of Terahertz Electromagnetic Radiation from Nanoscale High-Tc Josephson Junctions

Tech Area / Field

  • INF-ELE/Microelectronics and Optoelectronics/Information and Communications
  • INS-MEA/Measuring Instruments/Instrumentation
  • PHY-RAW/Radiofrequency Waves/Physics

Status
3 Approved without Funding

Registration date
24.03.2010

Leading Institute
Russian Academy of Sciences / Institute of Radioengineering and Electronics, Russia, Moscow

Collaborators

  • CNRS / Institut Neel / Département: Matière Condensée et Basses Températures, France, Grenoble\nForschungszentrum Jülich GmbH / Institut für Festkörperforschung, Germany, Jülich\nTechnical University of Denmark, Denmark, Copenhagen

Project summary

A goal of the project. It is supposed to study feasibility and parameters of emission of terahertz electromagnetic radiation in naturally nanostructured high-Tc materials and artificially nanostructured high- Tc Josephson junctions, like stacked single crystals of Bi2Sr2CaCu2O8 and bicrystal YBa2Cu3O7-x thin-film junctions, correspondingly.

Present status of research area. Terahertz frequency range, spreading from 0.1 THz to 10 THz between microwave and near infrared spectral regions, attracts growing attention by researchers in information technology, solid state physics, biology, medicine and security. Conventional approaches to emission, detection and spectroscopy of electromagnetic radiation, used at microwave and near infrared ranges, are ineffective in “terahertz gap”. On the one hand, output power of coherent microwave sources falls down at terahertz frequencies, due to increased electromagnetic losses in resonators and decrease of frequency conversion efficiency of nonlinear elements. On the other hand, application of quantum oscillators at THz frequency range has a number of obstacles. The energies of THz phonons are comparable with thermal energy kT at room temperature, so it is necessary to use cryogenic temperatures to cool down THz quantum oscillators. In addition, most of quantum oscillators have a narrow interval of frequency tuning. According to recently published scientific results, application of the ac Josephson effect in nanostructured high-temperature superconductors (high-Tc) for emission of electromagnetic radiation at terahertz frequency band is supposed to be promising. In general, it is possible to excite electromagnetic wave in these structures, which can be tuned in wide frequency range, varying only a voltage bias across a Josephson junction. Participants of this project achieved outstanding results, which are highly recognized by world scientific community and show great potential of high-Tc Josephson junctions for THz detection and spectroscopy. These results indicate on and logically related with a new research field, THz emission by high-Tc Josephson nanostructures.

The influence of the project proposed on a progress in research area. After successful fulfillment of the project, optimal conditions of THz emission by high-Tc thin-film bicrystal Josephson junctions will be determined. Efficiency of terahertz emission in a presence of positive feedback, when junction is placed into external resonance structure will be analyzed. Applications of the intrinsic ac Josephson effect in stacked single crystals of Bi2Sr2CaCu2O8 for terahertz emission will be considered.

Skills of project participants in research area. The project is presented by a group of research scientists of Kotel’nikov Institute of Radio Engineering and Electronics of the Russian Academy of Sciences with broad experience (for 20-30 years) of research and development of weak-linked superconductor structures; high sensitive receivers and spectral devices of millimeter, submillimeter and far infrared wave length bands; computer systems of data acquisition and processing. Participants of the project obtained a number of outstanding results, which were published and presented at international conferences and were recognized by world scientific community.

Expected results and their application in the project. The experience of project participants will be used in fabrication of low-ohmic YBa2Cu3O7-x thin-film Josephson junctions, high-quality stacked Bi2Sr2CaCu2O8 crystals and analysis of generation of terahertz electromagnetic radiation in these objects. In the case of successful fulfillment of the project, the results can be applied in terahertz electronics, telecommunications and information technologies. Data obtained can be used in development of terahertz sensors and imaging devices for airport security and medical scanning as well as new experimental technologies for a basic research in solid state physics, chemistry and biology.

Meeting ISTC goals and objectives. This project corresponds completely to the goals of ISTC. Its realization makes possible for IRE RAS research group members, which have knowledge and skills in military research and development, to exclude involuntary activity on contracts, related to development of new military technology (which provides IRE RAS with additional financing) from their work plans. Realization of the project will make possible IRE RAS research group members, participated in the project, to enforce reorientation of their activity from military to peaceful sphere; to quicken their integration into international scientific community owing to expansion and consolidation of international contacts and participation into international scientific conferences and symposia; to develop technological, fundamental and applied research in the peaceful aims, especially in the field of preservation of the environment. This project has solely peacful orientation, so it meets completely the goals and objectives of ISTC.

Scope of activities. According to aforesaid, the main goals of the project proposed are the following:

  • Further development of methods of Josephson nanostructure fabrication, which provides high-quality low-resistance junctions by dc sputtering in high-pressure oxygen atmosphere and additional oxygenation after patterning.
  • Aanalysis of THz emission in bicrystal Josephson junctions by synchronization with external probe signal and Josephson impedance spectroscopy in frequency region of 50 GHz - 5THz. Study of Josephson linewidth and its dependence on junction parameters, voltage bias, temperature and electromagnetic environment.
  • Theoretical analysis of conditions and requirements, which Josephson junctions and their electromagnetic environment should meet to provide effective terahertz emission. In particular, junctions in external resonant system with positive feedback will be considered.
  • Study of THz emission by the intrinsic ac Josephson effect in stacked crystals of Bi2Sr2CaCu2O8.
  • Analysis of application options for high-Tc nanostructures in development of THz electromagnetic radiation devices for real-life practice.
  • Presenting of the results achieved to the international scientific community.

Role of foreign collaborators and partners. Prof. J. Mygind (Danmark Technical University), Dr. U. Poppe (Institute of Microstructures, Juelich Research Center, Germany), Prof. P. Monseau (Neel Institute, France) are kindly consented to be collaborators of the project. Prof. J. Mygind is well-known as an author of a number of works on nonstationary Josephson effect and its microwave applications. Dr. U. Poppe is a recognized expert in high-Tc thin-films and its application in mm-wave diagnostics and magnetometry. Prof. P. Monseau is well-known researcher in physics of quasi-one-dimensional conductors and stacked high-Tc single crystals (whiskers). Participants of the project have close long-term relations with Prof. J. Mygind, Dr. U. Poppe, Prof. P. Monseau.

Technical Approach and Methodology. Special Josephson junctions will be used for study of THz emission. Thin epitaxial high-Tc films from YBa2Cu3O7-x, will be fabricated on bicrystal NdGaO3 substrate by the method of dc sputtering at high oxygen pressure. Josephson structures will be formed by ultraviolet lithography. A quality of HTSC cation ordering at bicrystal boundary will be controlled by transmission electron microscopy. Additional oxygen loading will be provided to obtain low-ohmic junctions for THz emission. Furthermore, participants of the project have a unique technology of growing stacked single crystals (whiskers) from high-Tc material Bi2Sr2CaCu2O8 and patterning nanostructures from them by focused ion beam.


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