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Bulk crystal growth and characterisation of nonlinear optical crystals by unidirectional growth method |
| Jerome S. Das |
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Department of Physics, Loyola College, Chennai, Chennai 600034, India |
| Abstract |
| In recent years there has been considerable interest to synthesize nonlinear optical materials with excellent second order optical non linearities owing to their potential application in electro-optic and opto-electronics devices. Nonlinear optics (NLO) is at the forefront of current research because of its importance in providing the key functions of frequency shifting, optical modulation, optical switching, optical logic and optical memory for the emerging technologies in the areas such as telecommunications, signal processing and optical interconnections. The rapid development of optical communication systems has led to a demand for nonlinear optical materials with high optical quality. Due to the technological importance of these nonlinear crystals, the need for good quality crystals has grown dramatically in the last few decades. The wide range of applicability of bulk single crystals is evident in the fields of semiconductors, infrared detectors, nonlinear optics, piezoelectric oscillators, photonics and optoelectronic industries. The key factors for materials selection depend not only on the laser condition but also on the physical properties of the crystal, such as transparency, damage threshold, conversion efficiency, phase matching, temperature stability and size of the crystal. Bridgeman-stockbarger method, Czochralski methods etc. are known for bulk crystal growth techniques from melt. However in these methods, the transparency and other mechanical properties of the grown crystals are affected due to thermal stress. The crystals, completely decompose at their melting point, cannot be grown by these methods. And also, growth technology plays a principal role for the non-linear optical susceptibilities. This is a main reason for the modification of the existed technological processes. It is reported that solution growth overcomes these difficulties due to its simplicity and convenience.
The unidirectional Sankaranarayanan - Ramasamy (SR) solution growth method attracted the researchers due to the growth of defect free transparent bulk single crystals along a particular axis. The unidirectional growth of bulk single crystals and their characterization towards device fabrication have assumed great momentum due to their significance in both academic and applied research. Simple experimental techniques, unidirectional growth, 100% solute-solid conversion, minimum thermal stress and prevention of the microbial growth are the interesting features of this technique. Due to these reasons, our interest is focused towards the development of several NLO crystals by Sankaranarayanan – Ramasamy (SR) method. All the grown crystals were subjected to various characterizations such as single crystal X-ray diffraction analysis, FTIR analysis, optical and thermal studies and the results were discussed in detail.
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Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Jerome S. DasSee On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17 Submitted: 2013-03-25 10:05 Revised: 2013-07-19 10:16 |