High performance widely tunable chromachip lasers

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As part of the "High performance widely tunable chromachip lasers" research project we have investigated new types of solid-state microchip lasers and nonlinear wavelength conversion by the Quasi-Phase-Matching process as follows :(1) We have demonstrated highly efficient laser oscillation using highly concentrated Nd-doped YAG ceramics by grain boundary controlling. The spectrum bandwidth was controlled by changing the composition structure : Nd : YSAG ceramics that have Al sights partially replaced by Sc has 5 times wider the gain band width compared with Nd : YAG.(2) A new model that describes theoretically the thermal birefringence in high power state lasers by changing the orientation of crystal axis from <111> to <110> or <100>-axis cut without any other internal optics into the optical resonator was developed. Moreover, a new pumping method that reduces the heat generation was proposed and experimentally proved.Directly pumping into the emitting level of Nd : YAG lasers improves … More the quantum defect but the absorption efficiency is poor for low concentrated Nd : YAG (1.0-at.% Nd, usually used in construction of lasers). We demonstrated that highly Nd-doped YAG ceramics has the potential to overcome this disadvantage, assuring high absorption efficiency for this new pumping scheme. Finally, simulation source code by FEM that estimate the heat generation and its thermal problem was developed.(3) We have developed an 'in-situ' poling system that optimizes the QPM fabrication process of MgO : LiNbO_3 that is characterized by a high damage threshold. Then we have realized a periodically poled 3-mm thick MgO : LiNbO_3. Moreover, we found the way for broadening the acceptance bandwidth by using d_31 (= d_32) instead of the normal d_33 coefficient.(4) During this research project were published 25 scientific papers and 6 review papers, 33 presentations were given at international meetings and 24 at domestic meetings, as well as 12 invited talks. Finally, we have received 4 awards. Less