This BRITE project has permitted to bring to an industrial level the crystal growth process of a new laser host.
a.axis LNA crystals of 50 mm in diameter and more than 200 mm in length have been grown in a reproducible industrial process.
Rods and slabs of great dimensions have been cut and polished achieving specifications comparable to those of Nd:YAG.
A full characterization of this new laser crystal has been carried out for all the thermomechanical as well as optical properties. Two prototypes of high power laser sources using rods and slabs geometry have been designed and built.
The main drawbacks of this study are:
1. It has been proved that c.axis LNA crystals were impossible or at least very difficult to grow in a reproducible way. This forbids to cut long rods along the optical axis which is the best orientation in respect to the anisotropic thermal conductivity of LNA. It gives a strong limitation to the maximum thermal load of the rod thus lowering the output power of the laser source.
2. The energy transfer between chromium and neodymium does not seem to be really efficient in LNA. Only a small smoothing of the thermal gradients inside of the rods can be observed due to STON effect. This is not enough to improve the laser efficiency which remains lower than the efficiency of YAG.
3. The thermal load limit of LNA is lower than expected severely limiting the output power.
In this way, the objectives of the project have not been achieved, and we can say that LNA is not the material of choice for high power solid state laser.
THE PROJECT AIMS TO REALIZE A POWER SOLID STATE LASER IN THE RANGE OF 1 KW USING A MATERIAL ALTERNATIVE TO THE YAG, THE LANTHANUM-NEODYMIUM HEXA-ALUMINATE (LAMGAL11O19 : ND OR LNA).
THE MAIN OBJECTIVE OF THIS RESEARCH IS TO INCREASE THE YIELD OF THE LASER BY STUDYING THE EFFECT OF A SENSITIZER ON THE EMISSION OF THE NEODYMIUM. SEVERAL POSSIBLE SENSITIZERS WILL BE TRIED. A COMPLETE CHARACTERIZATION OF THE MATERIAL WILL BE PERFORMED BY MEASURING ALL THE THERMAL, MECHANICAL AND OPTICAL PARAMETERS WHICH ARE NEEDED FOR THE DESIGN OF A HIGH POWER AND HIGH BEAM QUALITY LASER HEAD. A PREDESIGN OF THE RESONATOR WILL PERMIT TO STUDY THE FLASH PUMPING OF THE MATERIAL FOR A CW, PULSED OF SWITCHED LASER EMISSION.
AT THE SAME TIME, THE LASER DIODE PUMPING WILL BE STUDIED WITH THE SMALL RODS AVAILABLE AT THE BEGINNING OF THE RESEARCH. AT THE END OF THE PROJECT, TWO LASER HEADS WILL BE BUILT IN THE RANGE OF 1 KW FOR THE ROD LASER AND IN THE RANGE OF 300 W FOR THE SLAB LASER.
Funding SchemeCSC - Cost-sharing contracts
20090 Segrate Milano
91941 Les Ulis