Laboratory of Optical and Quasioptical Investigation and Optoelectronic Devices Design for Infocommunication Systems
Achievments
TECHNOLOGY OF MOST EFFECTIVE AND STABLE USE OF CRYSTALLINE MATERIALS FOR ELECTRO-, PIEZO- AND ACOUSTO-OPTICAL DEVICES TO CONTROL A LASER RADIATION
Description
The technology includes:
- measurement of all existing components of tensor for electro-, piezo- or elastooptic and related (e.g. piezoelectric or elastic) effects in crystalline materials under investigation (all necessary experimental equipment is available (see "Equipment") and corresponding techniques for measurements of crystals of all symmetry classes are developed);
- building of indicative and extreme surfaces for investigated effects as the only effective mean of geometric representation of 3rd and higher ranks tensors, and on this basis performing the 3D- analysis of spatial anisotropy corresponding effect (for this purpose special software was developed for building a three-dimensional images of surfaces);
- search of the global maximum for investigated effect and setting on the appropriate geometry of the sample with the highest value of electro-, piezo- or acousto-optic effect (also implemented on the basis of the developed software);
- calculations for increasing the efficiency and stability of the investigated crystalline material when it is used at the point of corresponding global maximum effect.
Innovative Aspect and Main Advantages
The proposed technology makes it possible to significantly improve the stability and efficiency of using of new or existing crystalline materials as working elements in solid-state optoelectronic devices that operate on the principles of electro -, piezo- or acousto-optic modulation of laser radiation. For many investigated by us crystals it was revealed that the direction of the electric field, uniaxial pressure, polarization and propagation of light and acoustic waves, which provides the most electro-, piezo- and acousto-optical parameters of crystalline materials in general do not coincide with the main crystal physical axes. Thus for the most efficient geometry corresponding to the global maximum of piezooptic effect with the angular coordinate Θ=42°, φ=30° and Θ=49°, φ=30°, it was possible to receive the increase of efficiency in 5 and 4 times in the piezooptical converters on crystals of lithium niobate and beta barium borate, respectively. Similarly, for lithium niobate crystals the maximum electroinductive path difference is almost 3 times greater (for Θ=54°, φ=90°), and the extreme value of the acousto- optical quality parameter for isotropic diffraction of light is 2.4 times greater (for Θ=60°, φ=7°), compared with the corresponding parameters for the standard geometry of straight cuts of these crystals. This enables to increase in the same amount of times the efficiency of lithium niobate crystals as working elements in corresponding devices for laser radiation control.
In addition, the use of crystalline materials at the point of their maximum electro-, piezo- or acousto-optic effects also guarantees a significant increase in stability values of investigated working parameter of the sample and thus the increase of stability of technical characteristics of the device.
Areas of Applications
The proposed technology can be successfully used in the development of electro-, piezo- or acousto-optical cells for the cases where the working elements of these devices are novel or already existing crystalline materials. In addition, the results of the development can be implemented in those areas of the economy where the crystalline materials used as sensitive elements of optical sensor devices or as components in various optoelectronic and laser devices in various scientific and industrial equipment, in particular, to improve the modulation of optical signal in modern information and communication systems.
Stage of Development
Experimental samples are available for demonstration and are laboratory tested.
DEVELOPMENT OF OPTICAL AND QUASI-OPTICAL (SUB-TERAHERTZ) TECHNOLOGY FOR CHARACTERIZATION OF BASIC FUNDAMENTAL PARAMETERS OF ISOTROPIC AND ANISOTROPIC MATERIAL
The development of optical and quasi-optical (sub-terahertz) technology to characterize the basic fundamental parameters, namely refractive indices of isotropic and anisotropic materials based on developed and created by us two experimental setups (general view and setup schemas see «Equipment»).
This setup corresponds to the best world analogues (or even exceed them).
The Main Advantages of Created Setups:
- simplification of the measuring process and the experimental data processing that guarantee the accuracy improvement of refractive index measurement;
- automation that provides express-analysis with high accuracy on the refractive indexes of plane-parallel samples of optical materials;
- the possibility of non-destructive testing, which provides a complete conformity of measuring parameters of samples for their further practical application;
- the possibility of measuring the refractive indices of all anisotropic media, including uniaxial and biaxial crystals of any symmetry class on one cut, thus saving expensive crystalline material;
- the possibility to determine the dispersion coefficients of optical refraction through the use of multiple sources of coherent radiation.
Theoretically calculated accuracy of refractive index measurement on the optical experimental setup is 3.5x10-6=0.0000035. Based on the experiment such results were achieved: n0=2.2868±0.0002, ne=2.2032±0.0002 - LiNbO3 crystals and n0=1.5436±0.0005, ne=1.5527±0.0005 - for crystalline quartz.
Industries and Applications
The proposed setup can be successfully used both for research and for non-destructive express-measurements of refractive indices of plane-parallel plates from isotropic and anisotropic materials in industrial laboratories or for those companies and firms that are engaged in growing crystals and creation optoelectronic devices on their basis.
COMPLETED DEVICE WITHIN PREVIOUS GRANTS
Based on the developed technology for more efficient use of anisotropic materials of solid state optoelectronics the experimental model of highly efficient acousto-optic cell to modulate powerful input information signal for optical-fiber transmission system was designed and fabricated.
As the material for acoustofiber LiNbO3:MgO crystal was used. This crystal was grown, cut and trimmed by "Carat". The orientation of the sample is selected according to the geometry found to be most effective for acousto-optic interaction, providing more than twice higher the value of the acousto-optical quality compared to traditionally-used acousto-optical geometry. Light box cell has a dimension of 6x9 ìì2.