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Lithium Niobate Crystals

#A-1033


Periodically and Chirped Periodically Poled Lithium Niobate Crystals with Strong Suppressed Photorefraction for Advanced Quantum Electronics

Tech Area / Field

  • MAT-OTH/Other/Materials
  • PHY-OPL/Optics and Lasers/Physics
  • PHY-SSP/Solid State Physics/Physics

Status
8 Project completed

Registration date
28.05.2003

Completion date
17.04.2008

Senior Project Manager
Endrullat B

Leading Institute
Institute for Physical Research, Armenia, Ashtarak-2

Collaborators

  • San Jose State University / College of Science, USA, CA, San Jose\nMontana State University / Department of Physics, USA, MT, Bozeman

Project summary

The goal of this project is development of an advanced technology for the growth of periodically and chirped-periodically-poled lithium niobate crystals with strong suppressed photorefractive effect doped with nonphotorefractive (Hf) and co-doped with rare-earth impurity ions. Such crystals will have a wide range of applications in various fields of quantum electronics, particularly in wavelength pision multiplexing and optical telecommunication systems.

Introduction and Overview

Improved methods in preparing lithium niobate (LN) crystals with periodically poled domain structures (PPLN) have led to an increase in its use in devices that depend on quasi-phase matching techniques. Such structures provide a reliable and promising approach for the development of efficient photonic systems that rely on second-harmonic generation in the blue-green spectral region and optical parametric oscillation. Through recent advancements on the engineering of chirped-periodically-poled lithium niobate (CPPLN) crystals, additional application possibilities, such as broadband second harmonic generation, multi- and difference frequency generation, etc are apparent.

Currently, PPLN structures are formed either during or after the growth cycle is complete. The most extensively used post-growth methods allow a domain inversion depth of no more than 1 mm. For thicker samples of PPLN crystals, the periodic domain structures must be formed directly during the growth process using methods such as the laser-heated pedestal technique, or the Czochralski method via rotation-induced growth striations. The last method despite of some disadvantages is the most promising among these methods. At last, by the author of the current proposal, recently it has been shown, that an external periodic electric current applied to the crystal-melt system during the growth process can result in the formation of high quality periodic structures in LN crystals. The mentioned method was successfully used for the growth of pure as well as doped with various transitional metal and rare-earth impurity ions PPLN and CPPLN crystals. The controlled formation of 4-50 mm wide domains along the a-axis of the crystals in lengths of 20 mm without interruptions or modulations in domain size was possible. A very important problem connected with the photorefractive effect, which still exists in PPLN crystals during high average-power operations will be solved by doping the crystal with recently discovered new nonphotorefractive Hf ions, which already at relatively low concentrations guarantees photorefraction stability of crystals to laser radiation.

Effect of the proposed project on progress in the given area

The development of an advanced technology for the growth of high “optical damage” resistance PPLN and CPPLN crystals with greater usable areas and domain inversion depths and beneficial combination of excellent non-linear properties of the material as well as the favorable optical processes originated by the incorporated impurity rare-earth ions will lead to obtaining of very promising integral-optical elements with high degree of integration.

Investigation of relevant nonlinear optical, optical, photorefractive and spectroscopic properties of grown doped PPLN and CPPLN crystals will determine possibilities for various applications of these crystals in advanced quantum electronics.

The competence of the participants of the project

The key personnel of the project are widely experienced in the fields of crystal growth, nonlinear optics laser physics and spectroscopy. They are actively engaged in the growth and investigation of various oxide crystals including doped ferroelectrics. Many aspects of the influence of physic-chemical peculiarities of synthesis, growth conditions, impurities and post-growing procedures has been thoroughly investigated on the stoichiometry and various physical properties of mentioned crystals.

Expected Results and their Application

Development of an advanced technology for the growth of high optical quality large periodically poled and chirped-periodically-poled lithium niobate crystals with strong suppressed photorefraction doped with various rare-earth impurity ions.

Investigation of relevant nonlinear, nonlinear optical and spectroscopic characteristics of grown crystals will allow to determine possibilities for their application in various fields of advanced quantum electronics, particularly as wavelength converters in wavelength pision multiplexing systems and as integral-optical elements with a high degree of integration for “all-in-one crystal” devices.

The fulfillment of the proposed research will lead to new knowledge on physic-chemical processes accompanying the growth of PPLN and CPPLN crystals as well as on activated non-linear materials.

Scope of Activities

The project is planned for 24 months and will be performed in the following consequence:


- Growth and manufacturing of PPLN and CPPLN crystals doped with various concentrations of nonphotorefractive (Hf) and rare-earth ions.
- Investigation of physic-chemical processes accompanying the growth of these crystals by the Czochralski technique with applied to the crystal-melt system of an electric current.
- Investigation of the influence of the type and concentration of impurity ions as well as growth conditions on the formation of periodic poled structures in these crystals.
- Investigation of photorefractive, non-linear optical and electro-physical properties of crystals under study.
- Theoretical and experimental study of spectroscopic characteristics of grown crystals.
- Development of optimal growth conditions of an advanced technology for the growth of PPLN and CPPLN crystals with strong suppressed photorefraction doped with rare-earth impurity ions and elaboration of recommendations for subsequent applications of obtained crystals in various branches of advanced quantum electronics.

Meeting ISTC Goals and Objectives

The project meets to the purposes ISTC and its execution will allow:

- To integrate the efforts of highly qualified scientists and engineers who possess knowledge and skills related to weapons on the solution of national and international technical peace problems;

- The development of these crystals will excite well-defined commercial interest for laser material producers in Armenia and neighboring countries and will promote creation of new job opportunities in Armenia, as well as will increase possibilities in participation of defense scientists in the civilian projects.

Role of Foreign Collaborators:

The cooperation with collaborator implies:


- information exchange during the realization of the project;
- joint discussion of project results;
- comments to the ISTC technical reports;
- sharing of scarce materials and obtained samples;
- joint investigations.

Technical Approach and Methodology

The following will be utilized for implementation of the goals of the project:


- Improved Czochralski technique via rotation-induced growth striations and a new method developed by the author of the project based on application of an external rectangular electrical current to the crystal-melt system during the growth process.
- Experimental methods for investigations of absorption, excitation and luminescence spectra of doped polar materials as well as methods of a theoretical spectroscopy.
- Experimental methods for investigation of second harmonic generation and photorefractive processes.
- Experimental method for wavelength conversion based on the cascading of two second-order processes.


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The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.

 

ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.

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