SM2E.3.pdf
Advanced Photonics Congress © 2012 OSA
AgBr-TlI, AgBr-KRS-5 photonic crystals and fibers based on them for Middle and Far infrared A. Korsakov,1 A. Chazov,1 L. Zhukova1, N. Terlyga1, D. Vrublevsky ,1 V. Korsakov,1 V. Zhukov1 1 – Ural Federal University named after the first President of Russia B.N.Eltsin, 620002, 19 Mira str., Yekaterinburg, Russia E-mail:
[email protected]
Abstract: Crystals of new composition for manufacturing of photonic fibers for middle and far infrared range are described. Doping of AgCl-AgBr solid solutions with TlI resulted in higher photostability and wider transmission range of grown crystals and extruded fibers. OCIS codes: (160.2290); (160.4330); (160.4760).
Crystalline substances make new class of materials for using them in the field of infrared fiber optics. Basic requirements imposed to such materials are their ability to transmit radiation in a wide range from visible to far infrared and absence of cleavage with simultaneous presence of plasticity. Today basically two kinds of materials posses such properties - AgClxBr1-x and KRS-5 crystals [1]. But AgClxBr1-x crystals have pure photostability, meanwhile KRS-5 ones reveal strong ageing effect due to recrystallization. These disadvantages gave occasion to searching for new crystals with improved properties to be used for extruding optical fibers (including those with microstructure and non-linear properties). AgCl-AgBr and KRS-5 solid solutions have similar physical and chemical properties (melting points, transparency in infrared region) and this fact can be used for their combination. Based on this conclusion thermodynamic research of phase equilibrium diagrams of double systems on the basis of silver bromine and thallium iodine has been performed. Stability of solid solutions according to the energy theory of isomorphous miscibility of components has been evaluated as well [2]. The same has been done for the system AgBr-KRS-5; crystal lattice of this system has also been modeled. Silver halides - AgCl и AgBr – represent ionic crystals with NaCl structure when in solid state. When speaking about lattices of different types in case of AgBr and AgI one can see the other situation. If concentration of AgI in AgBr is low the lattice will remain of cubic structure. Based on theoretic calculations and modeling of crystalline lattices as well as experimental studies, existence of region of substitutional solid solutions has been discovered in AgBr-TlI system (Fig. 1). Concentration of TlI can be up to 14 mol.% in temperature range from 298 K to 763 K. It has been discovered for this system that transition from cubic syngony (NaCl structural type) to hightemperature rhombic modification takes place at 473 K. Melting point of the above mentioned solid solutions is within the range of 601-692 K depending on the composition.
Ag Br
I Tl
Fig. 1. Model of Ag0,86Tl0,14Br0,86I0,14 solid solution lattice
SM2E.3.pdf
Advanced Photonics Congress © 2012 OSA
Using special technological methods and equipment for manufacturing charge and crystal growth we have developed novel photostable crystals of solid solutions with composition Ag 1-xTlxClyIzBr1-y-z (0.003≤x≤0.040; 0.066≤y≤0.246; 0.004≤z≤0.048) и Ag1-xTlxBr1-xIx (0
