We demonstrate optical power limiting by what we believe to be a new mechanism of nonlinear absorption, which involves a quasi-resonant ground-state absorption that is either phonon assisted or assisted by the presence of defect sites (tail absorption). Such a mechanism provides high transmittance at low intensity yet optical limiting under cw conditions. The sample used was a novel solgel-processed Er3+-doped multicomponent silica glass. In this system the nonlinear absorption process is achieved because the resonant excited-state (4I13/2 → 4S3/2) absorption cross section is larger than the quasi-resonant ground-state (4I15/2 → 4I9/2) absorption cross section.
© 2000 Optical Society of America
[Optical Society of America ]
Glauco S. Maciel, Abani Biswas, Christopher S. Friend, and Paras N. Prasad, "Quasi-Resonant Nonlinear Absorption for Optical Power Limiting: solgel-Processed Er3+-Doped Multicomponent Silica Glass," Appl. Opt. 39, 2433-2436 (2000)