Using confocal Raman and fluorescence spectroscopic imaging in 3-dimensions, we show direct evidence of inhomogeneous Nd(3+) distribution across grain boundaries (GBs) in Nd(3+):YAG laser ceramics. It is clearly shown that Nd(3+) segregation takes place at GBs leading to self-fluorescence quenching which affects a volume fraction as high as 20%. In addition, we show a clear trend of increasing spatial inhomogeneities in Nd(3+) concentration when the doping levels exceeds 3 at%, which is not detected by standard spectrometry techniques. These results could point the way to further improvements in what is already an impressive class of ceramic laser materials.
Particle accelerators require precise phase control of the electric field through the entire accelerator structure. Thus a future laser driven particle accelerator will require optical synchronism between the high-peak power laser sources that power the accelerator. The precise laser architecture for a laser driven particle accelerator is not determined yet, however it is clear that the ability to phase-lock independent modelocked oscillators will be of crucial importance. We report the present status on our work to demonstrate long term phaselocking between two modelocked lasers to within one dregee of optical phase and describe the optical synchronization techniques that we employ.
We demonstrate an optical technique, called laser-gain scanning microscopy (LGSM), to map dopant concentration profiles in engineered laser gain-media. The performance and application range of this technique are exampled on a Nd(3+) concentration profile embedded in a YAG transparent ceramic sample. Concentration profiles measured by both LGSM and SIMS techniques are compared and agree to within 5% over three-orders of magnitude in Nd(3+) doping level, from 0.001 at.% to 0.9 at.%. One of the unique advantages of LGSM over common physical methods such as SIMS, XPS and EMPA, is the ability to correlate optical defects with the final doping profile.
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