| The AgGaGesSe12 is an excellent infrared nonlinear optical crystal duo to its wide transparency range(0.63-16μm),large nonlinear coefficient(d31=30pm/V),laser damage threshold(225MW/cm2)and so on.It is expected to output 8-14 μm laser by pumped with Nd:YAG@1.064μm solid-state laser,which supplies the demands in military and civil fields.However,there are some problems in AgGaGesSe12 crystal preparation.(a)It’s difficult to synthesize high purity polycrystals by single-temperature zone method and double-temperature zone method.(b)The poor quality and many defects of single crystal is caused by volatile decomposition and segregation of components.In view of the above difficulties,the main contents of this paper are listed as follows:(a)In order to solve the problems of quartz crucible explosion and component deviation,we explore new synthetic methods like high-pressure-assisted method and 300g high purity single-phase polycrystal material is synthesized in one step.(b)Then we use seed-assisted vertical Bridgeman method to grow AgGaGesSe12 crystal.After we master the key control parameters such as heating rate,cooling rate and constant temperature time,the no-cracking AgGaGe5Sei2 single crystal with size of Φ20mm×100mm is obtained.And when we test the structure,composition and chemical properties of single crystal.we find that the single crystal has high quality,good uniformity and high thermal stability.The transmittance of 2.8mm uncoated crystal is up to 60%in the transmittance range,and the laser induced damage threshold of 5×5×2mm3 crystal is 220MW/cm2.(c)In addition,we simulate tuning curve of frequency conversion and calculate the phase matching angle,walk-off angle,allowable angle and interaction length of the crystal and so on,which can provide reference for the preparation of single crystal elements and laser experiment.We have prepared high quality AgGaGe5Se12 crystal by the improved high temperature Bridgeman method,which lays a foundation for the output of 8～14μm far-infrared laser. |
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