A detailed study of thermo-optic properties of 1.5 at.% Yb:Lu
2
O
3
single crystal is performed. Thermo-optic dispersion formulas are derived for d
n
/d
T
coefficient and thermal coefficient of the ...optical path. At the wavelength of 1.03 μm, d
n
/d
T
= 5.8 × 10
−6
K
−1
. High-precision temperature-dependent measurements of the thermal expansion coefficient
α
are performed. At the room temperature (RT),
α
= 5.880 ± 0.014 × 10
−6
K
−1
. Temperature dependence of the bandgap is analyzed, yielding RT value of
E
g
= 5.15 eV and d
E
g
/d
T
= –3.7 × 10
−4
eV/K. Sensitivity factor of the thermal lens is calculated for a diode-pumped Yb:Lu
2
O
3
crystal versus the pump spot radius and crystal temperature.
We report on the growth, structure, vibronic and spectroscopic properties of novel Yb3+-doped orthorhombic potassium yttrium double molybdate crystal, Yb:KY(MoO4)2. The layered structure of this ...material determines a strong polarization-anisotropy of absorption and emission bands of Yb3+ ions. The maximum stimulated-emission cross-section is 3.7×10-20 cm2 at ∼1.01 μm for light polarization E ∥ b and the lifetime of the 2F5/2 state is 0.46 ms. Naturally cleaved Yb:KY(MoO4)2 plates are suitable for microchip lasers at ∼1 μm.
Transparent glass-ceramics of magnesium aluminum silicate system based on nanosized MgAl2O4 spinel crystals nucleated by TiO2 and doped with Fe2O3 were developed. Their structure and spectroscopic ...properties were studied. The glass-ceramics are important as reference samples in development of saturable absorbers in the short-wave infrared spectral range (2-3 μm).
Compact Yb:KLu(WO
4
)
2
and Yb:LuVO
4
lasers diode-pumped at 978 nm are passively Q-switched by a single-layer graphene saturable absorber. The Yb:KLu(WO
4
)
2
laser generated 165 ns/0.49 μJ pulses ...at 1030 nm with 170 mW average output power and 12 % slope efficiency. With the Yb:LuVO
4
laser, 152 ns/0.83 μJ pulses were achieved. The output power reached 300 mW at 1024 nm, and the slope efficiency was 10 %. Laser operation in a plano-plano cavity is achieved with both crystals with thermal lensing playing a key role in their performance. A model describing graphene Q-switched Yb lasers is developed. Our results indicate the potential of graphene for passive Q-switching of ~1 μm bulk lasers.
Monoclinic Yb-sensitized (Tm, Ho)-doped KLu(WO4)2 nanocrystals of ~100 nm size have been synthesized by the modified Pechini sol-gel method. Their diode laser near-infrared (~980 nm) excited ...upconversion emission properties have been characterized at power densities in the range 30-355 W cm(-2). Bright white light composed of blue ~475 nm, green ~540 nm, and red ~650 nm emissions, corresponding to Tm(3+ 1)G4 → (3)H6, Ho(3+ 5)S2, (5)F4 → (5)I8, and Ho(3+ 5)F5 → (5)I8 electronic transitions, respectively, was generated by adjusting the Yb, Tm, and Ho contents in KLu(WO4)2 nanocrystalline samples. Chromaticity coordinates of the emitted white light can be tuned by modifying the excitation power density. The effect of Tm and Ho on the luminescence dynamics has been described by analyzing the upconverted emission intensity dependence on the excitation power, as well as from Stokes and decay time measurements. The effect on upconversion properties of further codoping with Eu in these (Tm, Ho, Yb)-doped KLu(WO4)2 nanocrystals has also been studied.
A comprehensive experimental investigation has been conducted into the high-power continuous-wave (CW) laser performance of isostructural Yb-doped vanadates, including three ordered crystals of ...Yb:YVO 4 , Yb:GdVO 4 , and Yb:LuVO 4 , and two mixed ones with compositional disorder: Yb 0.007 :Y 0.407 Gd 0.586 VO 4 and Yb 0.015 :Lu 0.52 Gd 0.465 VO 4 . The CW laser operation of the different vanadates is compared under nearly identical experimental conditions by using a high-power diode laser as the pump source. In addition to the output characteristics of the individual vanadate lasers, the polarization properties and optical bistability exhibited in the laser oscillation are also discussed. The spectroscopic properties closely related to the laser performance are compared and summarized for these Yb-doped vanadates.
We demonstrate passive mode locking based on the novel monoclinic double tungstate crystal Yb:KLu(WO4)2. We report the shortest pulses ever produced with an Yb-doped tungstate laser using a ...semiconductor saturable absorber. A pulse duration of 81 fs has been achieved for an average power of 70 mW at 1046 nm. We compare the performance of the polarization oriented parallel to the Nm- and Np-crystallo-optic axes. Results in the femtosecond and picosecond regime are presented applying either Ti:sapphire or diode laser pumping. The great potential of Yb:KLu(WO4)2 as an active medium for ultrashort pulses is demonstrated for the first time, to our knowledge.
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