ABSTRACT
A Kerr-lens mode-locked (KLM) thin-disk laser with Yb:LuAG ceramic was demonstrated. Yb:LuAG ceramic is an attractive material for high-power lasers due to its high thermal conductivity and large emission cross section. The highest output power of 17 W with a pulse duration of 130 fs was achieved. Moreover, the pulse duration of 88 fs was also obtained with a high-Q factor cavity. To the best of our knowledge, this is the first demonstration of a KLM thin-disk laser based on Yb:LuAG, including both ceramic and single crystal. The results show the usefulness of ceramic thin disks for high-power ultrashort pulse laser sources.
ABSTRACT
A high-resolution lens-coupled X-ray imaging detector equipped with a thin-layer transparent ceramics scintillator has been developed. The scintillator consists of a 5 µm thick Ce-doped Lu3Al5O12 layer (LuAG:Ce) bonded onto the support substrate of the non-doped LuAG ceramics by using a solid-state diffusion technique. Secondary electron microscopy of the bonded interface indicated that the crystal grains were densely packed without any pores in the optical wavelength scale, indicating a quasi-uniform refractive index across the interface. This guarantees high transparency and minimum reflection, which are essential properties for X-ray imaging detectors. The LuAG:Ce scintillator was incorporated into an X-ray imaging detector coupled with an objective lens with a numerical aperture of 0.85 and an optical magnification of 100. The scintillation light was imaged onto a complementary metal-oxide-semiconductor image sensor. The effective pixel size on the scintillator plane was 65 nm. X-ray transmission images of 200 nm line-and-space patterns were successfully resolved. The high spatial resolution was demonstrated by X-ray transmission images of large integrated circuits with the wiring patterns clearly visualized.
ABSTRACT
In this Letter, we demonstrate, to the best of our knowledge, the first Kerr-lens mode-locked (KLM) ceramic thin-disk laser. Ceramic laser gain media have many advantages for a high-power laser such as high fracture toughness, size scalability, low cost, and short time fabrication. By using the Yb:Lu2O3 ceramic thin disk, the pulse duration of 98 fs with the output power of 3.7 W was demonstrated. The shortest pulse duration was 86 fs with the decreased output power of 0.36 W. From our results, it was proven that a KLM thin-disk laser with ceramic gain media can become a new option for high-power, sub-100 fs pulse laser sources.
ABSTRACT
Yb:LuAG is a promising gain medium for high-power lasers due to its high thermal conductivity and large emission cross section. Although narrowband gain media such as Yb:LuAG are not considered to be suitable for the generation of sub-100 fs pulses, we have achieved generation of 91 fs pulses with Yb:LuAG ceramic by the Kerr-lens mode-locking (KLM) technique. The obtained average power, pulse energy, and peak power were 1.64 W, 20.0 nJ, and 220 kW, respectively. These are, to the best of our knowledge, the first demonstration of KLM and the new records based on both Yb:LuAG ceramic and single crystal.
ABSTRACT
Yb:LuAG ceramic is very promising for thin-disk laser and amplifier architectures since it exhibits a higher thermal conductivity at high doping concentrations and a larger emission cross section than Yb:YAG. In this Letter, we present what we believe to be the first demonstration of a thin-disk laser based on Yb:LuAG ceramic. A maximum output power of 101 W with an optical efficiency of 56% and a slope efficiency of 64% was obtained with a multimode laser resonator. Fundamental-mode laser operation with near diffraction limited beam quality (M2≈1.22) was also achieved. The fundamental-mode laser resonator showed the output power of 49 W, an optical efficiency of 31%, and a slope efficiency of 44%. A linearly polarized output beam was demonstrated in multimode operation using an intracavity Brewster window. The depolarization loss was measured to be as low as 0.15% per round trip.
ABSTRACT
A terbium gallium garnet (TGG) ceramic Faraday rotator (FR) with an isolation ratio of 33 dB was demonstrated at a laser radiation power of 257 W. This FR can be equipped with a large optical aperture by using ceramics technology to prevent laser damage at high-energy pulse operation. The thermal lens of a 257 W laser with a beam diameter of 2.6 mm had a focal length of 9.5 m, which is easily corrected using a spherical lens to suppress the undesirable effects of thermal lensing. The rotation angle of the FR was stabilized by water cooling. The results indicate that the TGG-ceramic-based FR is suitable for high-energy laser systems with high repetition rates.
ABSTRACT
Thermally induced depolarization and thermal lens of three Konoshima Chemical Co. laser-ceramics samples Yb(3+):Lu(2)O(3)(C(Yb) ≈ 1.8 at.%), Yb(3+):Y(2)O(3)(C(Yb) ≈ 1.8 at.%), and Yb(3+):Sc(2)O(3) (C(Yb) ≈ 2.5 at.%) were measured in experiment at different pump power. The results allowed us to estimate the thermal conductivity of the investigated ceramic samples and compare their thermo-optical properties. The thermo-optical constants P and Q and its sign measured for these materials at the first time.
ABSTRACT
The temperature dependence of the thermo-optic effects in single crystal and ceramic TGG were evaluated by using the Fizou interferometer method. The temperature dependence of the refractive index and thermal expansion are significantly improved at low temperature for both ceramics and single crystals. Our estimation using a figure of merit indicated that a TGG ceramics cooled to liquid nitrogen temperature can reduce thermal wave-front distortion by a factor of up to 4.7 with respect to that at 300 K, and can reduce thermal birefringence effects by up to a factor of 12 with respect to those at 300 K.
ABSTRACT
CW laser operation and first mode-locked laser operation of Yb:LuAG ceramic are reported. Efficient CW laser operation was obtained with maximum output power of 2.14 W and a 72% slope efficiency. Femtosecond mode-locked laser operation was achieved with pulse duration of 699 fs and a 200 mW average output power.
ABSTRACT
CW and mode-locked laser operation based on an Yb3+:Y2O3 ceramic thin disk is reported. In CW laser operation, an output power of 70 W with an optical-to-optical efficiency of 57.4% was achieved. A higher slope efficiency of 70% was also obtained with a 50-W pump laser diode with more suitable emission characteristics. In mode-locked laser operation, pulses as short as 547 fs with an average power of 7.4 W were obtained. To our knowledge, this is the first demonstration of a high power CW and mode-locked laser operation based on Yb3+:Y2O3 ceramic thin disks.
ABSTRACT
The temperature dependence of the thermo-optic effect in cryogenically cooled Yb:YAG ceramics was evaluated by measuring the thermo-optic coefficient (the derivative of refractive index with respect to temperature, i.e., dn/dT), thermal expansion coefficient (α), and thermal conductivity (κ) between 70 and 300 K. These parameters significantly improved at low temperature. Observed values indicated that a laser gain medium cooled to 70 K can sustain a thermal load up to 20 times higher than that at 300 K, for comparable thermo-optic effects. To our best knowledge, this is the first quantitative evaluation of the improvement in thermo-optic characteristics of cryogenically cooled Yb:YAG ceramics.
ABSTRACT
The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers.
ABSTRACT
We have successfully developed and demonstrated broadband emission Nd-doped mixed scandium garnets based on laser ceramic technology. The inhomogeneous broadening of Nd(3+) fluorescence lines results in a bandwidth above 5 nm that is significantly broader than that for Nd:YAG and enables subpicosecond mode-locked pulse durations. We have also found the emission cross section of 7.8 × 10(-20) cm(2) to be adequate for efficient energy extraction and thermal conductivity of 4.7 W/mK from these new Nd-doped laser ceramics. The new laser ceramics are good candidates for laser host material in a diode-pumped subpicosecond laser system with high efficiency and high repetition rate.
ABSTRACT
Diode-pumped mode-locked laser operation based on Yb(3+):Sc(2)O(3) and Yb(3+):Y(2)O(3) multi-gain-media oscillator has been demonstrated. 66-fs pulse duration with an average power of 1.5 W and 53-fs pulse duration with an average power of 1 W under 8-W laser diode pumping were achieved. The optical-to-optical efficiency was 18.8%. Additionally, 68-fs pulse duration with an average power of 540 mW from Yb(3+):Y(2)O(3) ceramic was also obtained.
ABSTRACT
A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.
ABSTRACT
Diode-pumped Kerr-lens mode-locked laser operation of Yb(3+):Lu(2)O(3) and nondoped Y(2)O(3) combined ceramics has been achieved; 65 fs pulses with an average power of 320 mW under 5 W of pump power were obtained at the center wavelength of 1032 nm. The spectral bandwidth and the time bandwidth product were 18.9 and 0.345 nm, respectively. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked laser operation based on Yb(3+):Lu(2)O(3) ceramic.
ABSTRACT
Diode-pumped Kerr-lens mode-locked laser operations of Yb3+:Sc2O3 ceramics have been achieved. 92 fs pulses with the average power of 850 mW under 3.89 W incident pump power were obtained at a center wavelength of 1042 nm. The optical-to-optical efficiency was 21.9%. 90 fs pulses with the average power of 160 mW were also obtained at a center wavelength of 1092 nm. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked Yb3+:Sc2O3 laser.
ABSTRACT
Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at.% ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb(3+)-ion lasants.
ABSTRACT
As the first demonstration of Faraday effect in a TGG ceramics, its Verdet constant at 1053 nm is evaluated to be 36.4 rad/Tm at room temperature which is same as that of the single crystal. In addition, the temperature dependence of Verdet constant is obtained experimentally. At liquid helium temperature, it is 87 times greater than that at room temperature.
ABSTRACT
Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb:YAG/Cr(4+):YAG microchip lasers with 0.72 MW peak power has been developed. Lasers with nearly diffraction-limited beam quality (M(2) < 1.09), oscillate at stable single- and multi- longitudinal-modes due to the combined etalon effects in the Yb:YAG and Cr(4+):YAG parts of its binary structure.
