Laser cooling of doped ferroelectrics
Tech Area / Field
- PHY-OPL/Optics and Lasers/Physics
3 Approved without Funding
Institute for Physical Research, Armenia, Ashtarak-2
- Polytechnique de Montreal / Department of Engineering Physics and Department of Electrical Engineering, Canada, QC, Montreal\nUniversita di Pisa, Italy, Pisa\nUniversity of New Mexico, USA, NM, Albuquerque\nMiguel Hernandez University, Spain, Elche\nUniversitat Freiburg, Germany, Freiburg\nUniversität Konstanz, Germany, Konstanz\nFraunhofer Institute of Physical Measurement Techniques(IPM), Germany, Freiburg
Project summaryThe Project aim. The basic aim of the Project is to considerably increase the efficiency of cooling effect in ferroelectric LiNbO3 (LN) crystals doped with Yb3+, Er3+ and Tm3+ impurity ions for new generation optical solid-state refrigerators. To achieve this goal is planned to beneficially combine in frame of single doped crystal the wide possibilities and advantages of this ferroelectric matrix. By use of the inherent to ferroelectrics pyroelectric effect it is proposed to develop simple temperature monitoring of the samples.
Current status. To date, the physics of the optical cooling effect in doped solids is well established. The main efforts of researchers are focused on studies of materials doped with trivalent rare-earth ions [1-10]. If in first experimental realization of optical cooling effect on the sample of ZBLANP:Yb3+ cooling to 0.3K below room temperature was achieved , now the temperature drops of solids to about of 150 K are realized, leaving far behind the thermoelectric Peltier cooling elements. And the continuous progress towards obtaining ever lower temperatures now more and more accelerated [11-17].
Significant steps towards improving the efficiency of the optical cooling have been made recently in various directions: the cavity-enhancement technique [18, 19], doped crystals with photonic bandgap structures , RE3+ -doped nanocrystalline powders [21-22], the usage of the optical superradiance regime of luminescence [23-25], etc.
Thanks to its photorefractive properties, LN crystal allows the creation of various photonic bandgap structures on it [26-28]. Such structures give the possibility via the Purcell effect directly to control absorption and luminescent properties of impurity ions [28, 29]. On the other hand, this matrix is predisposed to the formation of many-particle RE3+ optical centers, consisting of closely-spaced ions [30-32]. In the presence of such optical centers, the Dicke’s cooperative coherent optical superradiance effect should be substantially enhanced [23-25, 33, 34].
To the best of our knowledge, there are hitherto no experimental works concerning to the favorable combination of photonic bandgap structures of the matrix with the optical superradiance regime of luminescence in frame of single crystal. In case of successful implementation of the presented project such an optical cooler will be developed for the first time. These coolers will be of undoubted practical interest because of their advantages over thermoelectric and mechanical coolers: high reliability, no vibrations and electromagnetic noises, lithe power consumption, etc.
The project’ influence on progress in this area. Implementation of the Project will strongly promote development of both fundamental science in various areas of laser physics, solid-state physics, spectroscopy, etc., and the advanced-technology for creation of new generation optical solid-state refrigerators, as well as different elements of optoelectronics with high level of integration of various functional possibilities in frame of single crystals.
The participants’ expertise. Investigations suggested in the project are developed on base of results and ideas both of the project manager V.G. Babajanyan and key personal involved in the research team. The team of Project participants involves both theoreticians formulating problems and experimenters able to solve these problems. All specialists of our team are competent in those fields of science where they will participate which is confirmed by their publications (see Detailed Project Information).
Expected results and their application. During the Project implementation we expect to get the information about peculiarities and advantages of the optical cooling effect in the LN crystals doped Er3+, Yb3+ and Tm3+ impurity ions. It is planned to reveal necessary conditions for effective realization of the effect on the crystals under study. It is intended to design and create 1D and 2D photonic bandgap structures on the crystals, to obtain optimal conditions for optical superradiance regime, and to favorably combine these possibilities with good spectroscopic characteristics of the impurity ions. We plan to prepare a model of an optical refrigerator and to study its parameters. The fabricated device will be useful in research laboratories, in cosmic investigations, in bioscience, etc.
Meeting the ISTC goals and objectives. Corresponding to the ISTC goals, the proposed Project will enable organizing a new team of scientists and engineers for conducting scientific studies with peaceful purposes. In the framework of the Project the collaboration will be continued between the research groups of USA (NMU) and Armenia (IPR); this will promote the integration of Armenian team members into international scientific community. Experimental arrangements developed during execution of the Project may be used for solving various scientific and technical problems, as well as serve as a basis for organizing small science intensive industries, promoting thus the development of Armenian economics.
Scope of activities. The duration of the Project will be 30 months. The following main activities will be carried out within the project:
- growth and preparation of samples for research,
- design and creation of photonic structures, reveal the features of the “optical confinement” phenomenon,
- investigations of the optical supperradiance regime of luminescence in the samples under study,
- revelation of optimal conditions to combine in frame of single element the advantages obtained both from presence of photonic structures and realization of supperadiant regime of luminescence,
- preparation the mock-up of the optical cooler and investigations of its characteristics.
Role of Foreign Collaborators/Partners. Teams of IPR and University of New Mexico had already collaborated, and we plan in the frame of present Project to develop regular scientific discussions, to exchange data and ideas, to realize meetings and visits from both sides, to carry out joint screening tests, as well as to publish new articles and scientific reports. Since the foreign Collaborator is recognized a leader in this field of laser physics then he will coordinate all works during the whole project and monitor the quarter reports.
Technical approach and methodology. During the Project implementations the combination of standard spectroscopic and low-temperature methods with original techniques of investigations will be used. A large technical potential and vast experience of the low-temperature studies accumulated by U.S. team will be used. It is proposed to develop simple temperature monitoring of the samples on base of the pyroelectric effect inherent to ferroelectrics.
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