Abstract
Tooth whitening or bleaching is one of the most common dental procedures that optimize the white color of the teeth and minimize the simultaneous damage to the tooth structure. Light can ...speed up the whitening process with halogen lamps, light-emitting diodes, plasma arc lamps, and lasers. Our results show that combinations of a teeth whitening agent with laser light irradiation with a 0.44
µ
m blue laser diode or a 1.7
µ
m near-IR laser diode accelerate the whitening process not only during tooth irradiation but also within two weeks after the procedure.
Zn0.85Mn0.15Se crystals co-doped with Cr2+ and Fe2+ ions are investigated. Concentration quenching of Cr2+ and Fe2+ ions with an increase in Cr2+ ion concentration is demonstrated. The parameters of ...Cr2+ → Fe2+ ions nonradiative energy transfer are determined. It is shown that for the given Fe2+ doping level of ∼4 × 1018 cm−3 increasing the concentration of Cr2+ ions above 9.5 × 1018 cm−3 is inefficient.
•Concentration dependence of Cr2+→Fe2+ nonradiative energy transfer is analyzed.•Existence of optimal Cr2+ to Fe2+ ions ratio is demonstrated.•Excessive Cr2+ concentration leads to both Cr2+ and Fe2+ fluorescence quenching.
A new effect of the pulse shortening of the parametrically generated radiation down to hundreds of picosecond via depletion of pumping of intracavity Raman conversion in the miniature passively ...Q-switched Nd:
SrMoO
4
parametric self-Raman laser with the increasing energy of the shortened pulse under pulsed pumping by a high-power laser diode bar is demonstrated. The theoretical estimation of the depletion stage duration of the convertible fundamental laser radiation via intracavity Raman conversion is in agreement with the experimentally demonstrated duration of the parametrically generated pulse. Using the mathematical modeling of the pulse shortening quality and quantity deterioration is disclosed, and the solution ways are found by the optimization of the laser parameters.
The absorption cross-section of Cr
2+
ions in a range of cubic Zn
1–
x
Mn
x
Se (
x
= 0–0.3) solid solutions was determined using nonlinear transmission measurements. The maximum absorption ...cross-section of about 1.04 × 10
–18
cm
2
was determined and shown to be practically independent of the Mn content (
x
) in the solid solution.
We report efficient continuous-wave laser operation of a laser-diode pumped Pr:YAlO3 crystal in a power-scaled resonator arrangement. Using two pumping GaN-laser diodes emitting at 448 nm wavelength ...with maximum output power of 1 W each and a 5 mm long Pr(0.6 at.%):YAlO3 crystal, 290 mW of output power in the near-infrared spectral region (747 nm) with an oscillation threshold of about 500 mW has been reached. The maximum absorbed pump power was 1.5 W, resulting in the slope efficiency of 28%. Moreover, laser emission at two transitions in the visible part of the electromagnetic spectrum (747 and 720 nm) has been demonstrated employing the broadband laser resonator mirrors in connection with the tuning element (Lyot filter).
The temperature influence on the lasing properties of Pr:YLF crystal at orange laser transition is reported. The output characteristics were investigated at different active medium temperatures ...within the range of 80-300 K. Using a 1-W InGaN pump laser-diode, 350 mW of continuous-wave output power at 604 nm wavelength at 80 K crystal temperature is demonstrated. The corresponding slope efficiency related to the absorbed pump power was 46%.
The main goal of this work was to prove Er:YAlO3 laser generation at 1623 nm wavelength pumped by fiber coupled 1453 nm or 1461 nm laser diodes. The investigation concerned the influence of ...temperature ranging from 80 K to 300 K on the spectroscopic and laser properties of an Er:YAlO3 crystal in the eye-safe spectral region. For Er:YAlO3 active medium doped with 1.0% of Er/Y, laser emission was obtained in the temperature range from 80 K to 200 K. A maximal output peak power of 0.9 W and slope efficiency up to 27.4% with respect to the absorbed peak pump power were reached at a temperature of 80 K for resonant pumping at 1453 nm.
We report on the influence of temperature on the spectroscopic and lasing properties of alexandrite (Cr3+:BeAl2O4) crystal. The fluorescence lifetime, polarization-resolved absorption and emission ...spectra, and laser characteristics at 750 nm are described in detail within a 78-400 K temperature range. As a pumping source, a 3.5 W InGaN blue laser-diode operating at a wavelength of 444 nm was used. The best results achieved were at a crystal temperature of 353 K with 326 mW of continuous output power at a wavelength of 750 nm with a slope efficiency near 20% (related to absorbed pump power). At cryogenic temperatures, alexandrite laser generation at the so-called R-line, i.e. not in the vibronic mode, has been observed.
Mode-locking of a praseodymium based solid-state laser by a nonlinear mirror is reported, for the first time to the best of our knowledge. Pr:YAlO3 crystal having 0.6 at.% of Pr3+ ions was used as an ...active medium. For mode-locking, a nonlinear BBO crystal together with a properly designed dichroic mirror were employed to form an output coupler with intensity dependent reflection. A continuous-wave mode-locked laser operation with a mean output power of 100 mW was achieved under 3.5 W InGaN laser diode pumping. The laser emitted 250 ps pulses with a repetition rate of 105 MHz at a center oscillation wavelength of 747 nm.
The room-temperature spectroscopic properties of Cr2+ ions in Zn0.7Mn0.3Se and Zn0.7Mg0.3Se crystals co-doped with Cr2+ and Fe2+ ions were investigated and compared to Cr2+-only-doped ones. The ...“blue” shift of both absorption and fluorescence lines of Cr2+ ions in positions with nearby Fe2+ ions was demonstrated to be 350 cm−1 and 250 cm−1 for Zn0.7Mn0.3Se and Zn0.7Mg0.3Se crystals, respectively. This shift was shown to have a serious influence on the Cr2+-Fe2+ energy transfer process due to the worse energy resonance between Cr2+ and Fe2+ ions.
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