H. Manaa

Spectroscopic investigation of the chromium-doped LiNbGeO5 laser crystal

Abstract Polarized absorption and emission spectra, and temperature dependences of the fluorescence lifetimes and intensities for the chromium-doped LiNbGeO5 laser crystal are presented. Crystal symmetry and comparison with the infrared fluorescence properties of the Cr-doped Mg2SiO4 and Y3Al5O12 laser crystals seem to identify the active center as a Cr4+ ion in a tetrahedral site.

Spectroscopic study and laser operation of Cr4+-doped (Sr,Ca)Gd4(SiO4)3O single crystals

Abstract Cr-doped oxyapatite single crystals with formula AGd 4 (SiO 4 ) 3 O and A = Sr or Ca were grown and studied. The shape and the intensity of their optical absorption and fluorescence bands as well as the values and the temperature variations of the fluorescence lifetimes are characteristic of those of tetrahedrally coordinated Cr 4+ ions. Gain measurements show their potential wavelength tunability between about 1.2 and 1.5 μm. Room temperature laser action is demonstrated at 1.37 and 1.44 μm in the Ca- and Sr-compounds, respectively.

Saturable and excited state absorption measurements in Cr4+:LuAG single crystals

Abstract The performance of a Q-switched Nd-YAG laser using Cr4+:Lu3Al5O12 (LuAG) as a passive shutter is demonstrated with 35% conversion efficiency between the free-running and the Q-switched mode. From the transmission saturation curves, the ground state and the excited state absorption cross-sections were evaluated. Furthermore, the excited state absorption spectrum of Cr4+:LuAG in its absorption and emission domains was obtained and characterized. Pulsed laser emission of Cr4+:LuAG pumped at 1.064 μm was also obtained, though for a short period of time.

Excited state absorption in Mn5+: Sr5(VO4)3F

Abstract We report measurements of the excited state absorption (ESA) spectra of Mn:SVAP for both σ and π polarizations upon laser excitation at 700 nm. The results indicate that strong ESA with cross sections of the order of 10−18 cm2 covers most or all of the visible spectral region and extends to about 1150 nm. An even stronger ESA band exists in the blue and near ultraviolet region. The polarizations of the observed bands are not adequately explained by intraionic Mn5+ transitions, indicating that molecular orbital states lie at least as low as 24500 cm−1.

Excited-state absorption of Co2+ in MgF2 and KZnF3

We report on measurements of excited-state absorption spectra and absolute cross-sections in Co2+-doped KZnF3 and MgF2 at room temperature in the near-infrared domain. The data are compared with the predictions of the single-configuration co-ordinate model.

Luminescence properties, crystal growth and laser capability of Cr3+ -doped LMA

Abstract This paper reports on the crystal growth conditions, the fluorescence decays and the time resolved emission spectra obtained for different excitation wavelengths of Cr 3+ -doped lanthanum-magnesium hexa-aluminate LaMgAl 11 O 19 . An estimate of the stimulated emission cross-section is given and the experimental conditions of the numerous laser tests which have been unsuccessfully carried out by using various excitation pump sources (laser and flash lamps) are described.