Laser Forsterite

From these vievqjoints, we have developed a femtosecond NIR laser microscope with a home-built cavity dumped chromium forsterite (Cr F) laser as an excitation light source whose output wavelength is centered at 1260 run. In the following the set-up of the NIR laser microscope and its application to multiphoton imaging are presented. 

Confocal Microscope with a Chromium Forsterite Ultrafast Laser as an Excitation Source... 

Fig. 4.69. Laser-induced time-resolved luminescence spectra of in forsterite...

The femtosecond fluorescence up-conversion setup has been described elsewhere [13,14]. Briefly, a second harmonic (SH) of a home-made chromium-forsterite femtosecond laser tunable from 610 to 660 nm was used to excite the sample (Fig.2) [14]. The pulse duration of the SH pulses was about 50 fs at the full width at half maximum (FWHM). We were successful in the cavity-dumping operation of this laser [14] and kept the repetition rate as low as 4 MHz. Reduction of the repetition rate was necessary to avoid multiple hits of the same location of the sample as small as possible. The excitation intensity, controlled by a neutral density filter before the sample cell, was (0.5-l)xl012 photons/cm2/pulse. Special care was taken to work at the lowest excitation light intensity so that the effect of the exciton-exciton annihilation process was negligible. 

Fig. 2. A home-made chromium-forsterite femtosecond laser with a cavity dumper [14].

The assumption of local equilibrium at Alta has been tested by detailed laser fluorination analysis of in forsterite at one layered outcrop of the periclase and forsterite zones (Bowman and Valley 1999). Figure 17 is based on analysis of carbonates from the earlier work of Bowman and co-workers (Bowman et al. 1994 Cook et al. 

Petricevic, V, Gayen, S. K., and Alfano, R. R. (1989). Continuous-Wave Laser Operation of Chromium-Doped Forsterite, Opt. Lett. 14, 612. 

P.T. Guerreiro, S. Ten, N.F. Borrelli, J. Butty, G.E. Jabbour, N. Peyghambarian PbS quantum-dot doped glasses as saturable absorbers for mode locking of a Cr forsterite laser, Appl. Phys. Lett. 71, 1595-1597 (1997)... 

Visible luminescence of many centers, such as Cr ", Mn " and Ni ", has been found and interpreted in the visible range in synthetic forsterite excited with electrons and laser. The polarized absorption spectra and time-resolved luminescence spectroscopy of Cr"activated forsterite led to the discovery of at least two different kinds of Cr " emitting centers (Moncorge et al. 1991) that correspond to Cr " ions in two different sites of six-fold coordination. There are Cr " ions, probably substituting for Mg " ions in both the Ml and M2 sites, which form medium-field systems giving rise to " E-" T2 sharp line emissions at low temperatures with millisecond lifetimes around 700 nm and " T2, thermalized short-... 

Numerous spectral data appeared on natural forsterite as result of its continuous wavelength (CW) Raman spectra study under 532 and 780 nm laser excitations where Raman signals are accompanied by multiple luminescence lines and bands. Those luminescence spectral data exhibit much more emission centers than the... 

Fig. 4.171 (a-d) Laser-induced time-resolved luminescence spectra of Mn with zero phonon line at 100 K (a-b) and possibly Ni (c-d) in forsterite... 

The forsterite minerals in our study consisted of nine sample. Concentrations of several potential impurities luminogens are presented in Table 4.22. Laser-induced time-resolved technique enables to detect Mn " with zero phonon fine at low temperatures (Fig. 4.171a, b), possibly Ni " (Fig. 4.171c, d), Cr " in strong CF (Fig. 4.172a-c), Cr " in weak CF (Fig. 4.172d, e) and possibly (4.172f). 

Fig. 4.173 (a-f) Laser-induced cw luminescence spectra of several forsterite samples under 532 nm excitation (http //rruff.info)... 

Mohler R, White W (1995) Influence of structural order on the luminescence of oxide spinels Ci " activated spinels. J Electrochem Soc 142 3923-3927 Moncorge R, Cormier G, Simkon D, Capobianco J (1991) Fluorescence analysis of chromium doped forsterite (Mg2Si04). IEEE J Quantum Electron 27 114-120 Moncorge R, Manaa H, Boulon G (1994) Cr and Mn active centers for new solid state laser materials. Opt Mater 4 139-144... 

Fig. 5.60 (a-c) Laser-induced time resolved luminescence at 300 K (a), 100 K (b) and luminescence excitation (c) of green forsterite... 

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