High-inversion densities in Nd:YAG-upconversion and bleaching

• Published in: IEEE journal of quantum electronics Vol. 34; no. 5; pp. 900 - 909
• Main Authors: Guy, S., Bonner, C.L., Shepherd, D.P., Hanna, D.C., Tropper, A.C., Ferrand, B.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.1998; Institute of Electrical and Electronics Engineers
• Subjects: Bleaching; Diodes; Doped-insulator lasers and other solid state lasers; Efficiency, stability, gain, and other operational parameters; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Laser excitation; Laser optical systems: design and operation; Lasers; Neodymium; Optical materials; Optics; Physics; Planar waveguides; Pump lasers; Resonators, cavities, amplifiers, arrays, and rings; Semiconductor laser arrays; Stationary state; Waveguide lasers; Auger effect; Solid state lasers; YAG laser; Theoretical study; Optical amplifier; Thermal load; Gain; Neodymium lasers
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.668778

We report on the investigation of upconversion in Nd:YAG and its implications for intensely pumped devices. Analysis of lifetime measurements and the performance of a 1 at.% Nd-doped YAG amplifier give an Auger upconversion rate of 7/spl times/10/sup 3/ s/sup -1/. This is significantly smaller than previously reported, but modeling of the performance of Nd:YAG devices with high-inversion densities shows that even this rate can still seriously degrade the small-signal gain and significantly increase the thermal load. The variation of cross-relaxation and upconversion rates with doping level is also described. Finally, it is found that the effect of bleaching of the Nd:YAG absorption can lead to a reduced spatial overlap between the signal and inversion profiles and thus can also significantly reduce the gain.