title: Quasi-Resonant Nonlinear Absorption for Optical Power Limiting: solgel-Processed Er(3+)-Doped Multicomponent Silica Glass.
abstract: 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 Er(3+)-doped multicomponent silica glass. In this system the nonlinear absorption process is achieved because the resonant excited-state ((4)I(13/2) ? (4)S(3/2)) absorption cross section is larger than the quasi-resonant ground-state ((4)I(15/2) ? (4)I(9/2)) absorption cross section.
authors.forename: G S
authors.initials: GS
authors.lastname: Maciel
authors.forename: A
authors.initials: A
authors.lastname: Biswas
authors.forename: C S
authors.initials: CS
authors.lastname: Friend
authors.forename: P N
authors.initials: PN
authors.lastname: Prasad