A transparent “mixed” 7 at.% Er:(Lu,Sc)2O3 sesquioxide ceramic was fabricated by hot isostatic pressing of commercial sesquioxide powders at 1750 °C/200 MPa in argon atmosphere. It exhibited a cubic ...bixbyite-type structure (a = 10.198 Å), a mean grain size of 5.7 μm and high low-signal transmission of 79.1 % in the near-IR. The spectroscopic properties of Er3+ ions were studied. For the 4I11/2 → 4I13/2 transition, the stimulated-emission cross-section σSE is 1.30 × 10−20 cm2 at 2719 nm, the corresponding luminescence branching ratio B(JJ’) is 19.9 % and the radiative lifetime of the 4I11/2 state is 4.80 ms, as determined using a Judd-Ofelt theory accounting for intermediate configuration interaction. The crystal-field splitting of Er3+ multiplets was studied at 12 K. The ceramic exhibits a significant inhomogeneous broadening of spectral bands. An Er:(Lu,Sc)2O3 ceramic laser generated 342 mW at 2.71 and 2.85 μm with a high slope efficiency of 41.7 % (exceeding the Stokes limit) and a laser threshold of 125 mW.
•Transparent “mixed” 7 at.% Er:(Lu,Sc)2O3 sesquioxide ceramic.•Fabrication by hot isostatic pressing at 1750 °C / 200 MPa in argon atmosphere.•The stimulated-emission cross-section for Er3+ ions is 1.30 × 10-20 cm2 at 2719 nm.•The ceramic exhibits a significant inhomogeneous broadening of the spectral bands.•The ceramic laser generated 342 mW at 2.71&2.85 μm with a slope efficiency of 41.7 %.
Low-energy excitations can provide insight into the basic ultrafast nonequilibrium dynamics of condensed matter. High-energy femtosecond pulses in the long-wavelength infrared are required to induce ...such processes, and can be generated in an optical parametric chirped pulse amplification (OPCPA) system comprising three GaSe stages. A femtosecond Cr:ZnS laser serves as the front-end, providing the seed for the 2.0-µm pump and the 2.4-µm signal pulses without nonlinear conversion processes. The OPCPA system is pumped at 2.05 µm by a picosecond Ho:YLF regenerative amplifier at a 1-kHz repetition rate. The recompressed idler pulses at 11.4 µm have a duration of 185 fs and an unprecedented energy of 65 µJ, corresponding to a pump-to-idler conversion efficiency of 1.2%. Nonlinear transmission experiments in the range of the L2 infrared band of liquid water demonstrate the potential of the pulses for nonlinear vibrational spectroscopy of liquids and solids.
Highly-doped “mixed” transparent sesquioxide ceramics, 10 at.% Yb:(Lu2/3Sc1/3)2O3, are fabricated by vacuum sintering at 1700 °C followed by hot isostatic pressing (HIPing) at 1680 °C and 200 MPa. ...The ceramics are of single-phase nature with a cubic (C-type, a = 10.191 Å) structure and a mean grain size of 0.66 μm. They feature high low-signal transmission of 79.0% at 1.20 μm. The Yb3+ ions in “mixed” ceramics exhibit strong inhomogeneous broadening of the absorption and emission bands, with σSE of 0.43 × 10−20 cm2 at 1079.4 nm and an emission bandwidth of 25.7 nm. The crystal-field splitting for Yb3+ ions is revealed at 12 K. The Yb ceramic laser generated a maximum peak output power of 250 mW at ~1.04 and 1.08 μm with a slope efficiency of 40.3%. The ceramics are promising for mode-locked lasers at ~1.08 μm, including thin-disk geometry.
•Highly-doped “mixed” transparent sesquioxide ceramic, 10 at.% Yb:(Lu2/3Sc1/3)2O3.•Fabrication by vacuum sintering at 1700 °C followed by HIPing at 1680 °C/200 MPa.•The ceramic has a cubic structure (a = 10.191 Å) and a mean grain size of 0.66 μm.•The Yb3+ ions exhibit inhomogeneous broadening: the emission bandwidth is 25.7 nm.•The ceramic laser generated 250 mW at 1.04&1.08 μm with a slope efficiency of 40.3%.
Tm3+-doped cubic potassium yttrium fluoride, KY3F10, is a promising laser crystal for efficient watt-level lasers at ∼1.9 μm because of the relatively easy crystal growth by the Czochralski method, ...advantageous thermo-optical properties, high available Tm3+ doping levels and very efficient cross-relaxation mechanism. A compact diode-pumped 8 at.% Tm3+:KY3F10 laser generated 1.85 W at 1891 nm with a slope efficiency of 65.2% and a laser threshold of 450 mW. A negative thermal lens was detected in this crystal owing to the negative dn/dT coefficient (−8.9 × 10−6 K−1). Passive Q-switching of the Tm3+:KY3F10 laser by single-walled carbon nanotube saturable absorber was demonstrated yielding 13.2 μJ/490 ns pulses at a repetition rate of 58 kHz.
•Czochralski growth of cubic fluorite-type 8 at.% Tm3+: KY3F10 crystal.•Absorption and stimulated-emission cross-sections for Tm3+ ions.•Thermo-optic characterization: dispersion of dn/dT coefficients and thermal lensing.•Tm3+:KY3F10 laser generated 1.85 W at 1891 nm with a slope efficiency of 65.2%.•Passive Q-switching of the Tm3+:KY3F10 laser by single-walled carbon nanotubes.
Stable passive Q-switching of a Tm: LiYF4 laser is obtained using polycrystalline Cr2+: ZnS as a saturable absorber. The achieved maximum pulse energy of 0.9 mJ and peak power of 65 kW for a pulse ...duration of ∼14 ns represent substantial improvement and highest values for a passively Q-switched diode-pumped Tm laser operating at ∼1.9 μm.
We report the generation of mid-infrared (~2 µm) high repetition rate (MHz) sub-100 ns pulses in buried thulium-doped monoclinic double tungstate crystalline waveguide lasers using two-dimensional ...saturable absorber materials, graphene and MoS
. The waveguide (propagation losses of ~1 dB/cm) was micro-fabricated by means of ultrafast femtosecond laser writing. In the continuous-wave regime, the waveguide laser generated 247 mW at 1849.6 nm with a slope efficiency of 48.7%. The laser operated at the fundamental transverse mode with a linearly polarized output. With graphene as a saturable absorber, the pulse characteristics were 88 ns / 18 nJ (duration / energy) at a repetition rate of 1.39 MHz. Even shorter pulses of 66 ns were achieved with MoS
. Graphene and MoS
are therefore promising for high repetition rate nanosecond Q-switched infrared waveguide lasers.
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