Up-conversion Luminescence in Dye-Doped Crystals of Potassium Hydrogen Phthalate


  • We are grateful for support from the National Science Foundation and the Petroleum Research Fund of the American Chemical Society. We are appreciative of stimulating discussions with Prof. Alex Jen.


Optically nonlinear single crystals of potassium hydrogen phthalate were grown in the presence of a variety of laser dyes. Up-conversion fluorescence (as shown in the Figure) in the visible part of the spectrum was observed as a result of two excitation mechanisms involving trapped, oriented luminophores: two-photon absorption in general orientations, and absorption of the second harmonic of the fundamental beam at 800 nm, when aligned with the phase-matching direction.