Optical Coherent Transients and Hole Burning of the Elemental FLUORINE-7 - Elemental DEUTERIUM-5 Transition in Europium-Hydroxide

The narrowest inhomogeneous optical linewidth ever seen in a solid has been observed in Eu(OH)(,3). This transition is quadratically enhanced in a magnetic field and the results are explained completely in terms of second order perturbation theory and the coupling of crystal field energy levels. Optical coherent transients are reported here for the first time in this optically pure, stoichiometric material. The optical dephasing time, T(,2), is shown to be greater than 2 microseconds for the ('7)F(,0)-('5)D(,0) zero phonon transition. Hole burning, attributed to optical pumping of nuclear-quadrupole levels, has been used to measure the quadrupole splittings in the excited, ('5)D(,0), state. Due to the small magnetic moment, conventional magnetic resonance techniques have failed to make this measurement in all Europium compounds. The new technique developed and used in these hole burning measurements yields the quadrupole coupling coefficients, (VBAR)P(VBAR) = 11.6 MHz and (VBAR)P(VBAR) = 4.5 MHz for the 153 isotope and the 151 isotope, respectively. The qualitative behavior of line narrowing in Doubly-resonant two-photon-absorption induced four-wave mixing is explained in terms of the anomalous dispersion. The implications of this dispersion regarding the measurement of the homogeneous linewidth and hyperfine levels hidden within the inhomogeneous profile are discussed with regard to the particular example of LiTbF(,4).