Transparent composite Lutetium aluminum garnet (LuAG) ceramics were successfully synthesized by thermal diffusion bonding method. Three isothermal holding temperature of 1450°C, 1600°C, 1780°C for 10h under vacuum were used to
study the changes of bonding interface morphology, Optical microscope, SEM and laser interferometer (GPI-XP,zygo) study show that diauxic growth of grain interface appears when the thermal bonding holding temperature increased. The sintering mechanism of diauxic growth of grain interface during the thermal diffusion bonding was also discussed using diffusion theory. The diauxic growth of grain interface provides us the possibility to get high quality composite laser ceramics as we designed.
In order to mitigate the dopant concentration gradient by post-growth diffusion method, high optical quality Cr2+:ZnSe ceramics had been prepared by hot-pressing method with powders being diffusion doped in a previous step, which reduced the concentration gradient down to a grain size level. A optimal combination of sintering parameters, including
temperature, pressure, dwell time, have been determined (1050°C/150MPa/2h) according to background absorption
intensity. Comparison with diffusion doped CVD-grown ZnSe showed a stronger background absorption and blueshifted
emission peak, both indicating scattering sources inside material. Micro-structure observation proved the
inference above as being residual pores and inclusions, which could be eliminated or reduced by, as suggested here,
preliminary treatment of powders and enhancement of densification pressure and dwell time.
The relationship between optical scattering losses and microstructure, especially inside pores distribution, was studied in
transparent Nd:YAG and Yb:YAG ceramics. Specimens with different transmittance values were fabricated by vacuum
sintering from 1730°C to 1760°C for 30 to 50 h through a solid-state reaction method. Light scattering losses were
calculated from transmittance values measured by UV-Vis-IR spectrophotometer. Micromechanism, including inside
pores and grains on etched surfaces, was characterized via high magnification optical microscope. The porosities were
also counted in microscope observation. Curves of the relations between scattering losses (or transmittances) and
porosities were obtained. In addition, the genesis of inside pores and the process of exhaust were discussed in this paper.
Composite YAG/2.0at%Nd:YAG transparent ceramic was fabricated by solid-state reactive sintering a mixture of
commercial α-Al2O3, Y2O3, and Nd2O3 powders with tetraethoxysilane (TEOS) and MgO as sintering additives. A fully
dense YAG/2.0at%Nd:YAG ceramic with an average grain size of ~20μm was obtained by vacuum sintering at 1750°C
for 50h. There are almost no pores or second phases present at grain boundaries or inner grains. The in-line transmittance
reached 83.6% at the lasing wavelength of 1064nm and 82.0% at 400nm. The porosity of the sample was at the level of
several vol ppm. The composite YAG/2.0at%Nd:YAG transparent ceramics are promising to generate high-energy laser.
In this paper, the absorption and Fluorescence spectra of Cr4+,Nd3+:GGG (Cr,Nd:GGG) crystal, Nd:GGG crystal and Cr4+:GGG crystal are reported. In the absorption spectra there are big absorption bands at 400 and 520nm, which correspond to the 4A2→4T1 and 4A2→4T2 transitions. The luminescent spectra of Cr,Nd:GGG and Nd:GGG show that the luminescent center of Cr,Nd:GGG is at 1.062um, but the intensity is 6 times lower than that of Nd:GGG. The luminescent lifetimes of Cr,Nd:GGG is shorter than that of Nd:GGG. These may be caused by the existence of ground state absorption of Cr4+ which quenches the Nd3+ emission intensity. These Cr,Nd:GGG crystals may be potential materials for compact, efficient, high stability diode- laser-pumped passive Q-switched solid state laser.
We report on functional color centers and waveguide formed by using 800nm, 120fs, 200kHz pulse laser in alkali halide crystals such as KCl and LiF. These crystals are transparent in the wavelength ranging from 250-1000nm. After irradiated by the 800nm tightly focused femtosecond laser, the crystal changed to dark and color centers have been formed. Some of these color centers are useful and alkali halide crystal with these color centers is one type of laser crystal (color center laser crystal). And also photoinduced refractive index changes have been formed by focusing the laser beam.