Maximum Absorbed Pump Power Research Articles

Solid-state-reaction fabrication and properties of a high-doping Nd:YAG transparent laser ceramic

High-quality neodymium-doped yttrium aluminum garnet (Nd:YAG) transparent ceramic (4.0 mole percent) was fabricated by a solid-state reaction method and vacuum sintering. The microstructure, optical transmittance, spectral properties and laser performance were investigated. The average grain size of the sample is about 10 mm. The transmittance of a 2.8-mm thick sample reaches 79.5% at the laser wavelength of 1064 nm. The highest absorption peak is centered at 807 nm and the absorption coefficient is 13.9 cm−1. The absorption coefficient at the laser wavelength is 0.2 cm−1. The main emission peak is at 1064 nm and the fluorescence lifetime is 102 μs. A laser diode (808 nm) whose maximum output is about 1000 mW was used as a pump source and an endpumped laser experiment was performed. The 1064 nm-CW-laser output was obtained and the threshold is 733 mW. With 998 mW of maximum absorbed pump power, a laser output of 17 mW is obtained with a slope efficiency of 6.1%.

Laminar‐Structured YAG/Nd:YAG/YAG Transparent Ceramics for Solid‐State Lasers

A laminar‐structured YAG/1.0 at.% Nd:YAG/YAG transparent ceramic was fabricated by a solid‐state reaction method and vacuum sintering using high‐purity α‐Al2O3, Y2O3, and Nd2O3 as raw materials with tetraethoxysilane as a sintering aid. The microstructure, the optical property, and the laser performance of the ceramic composite prepared were investigated in this paper. It is found that the sample exhibits a pore‐free structure and the average grain size is about 15 μm. There is no secondary phase both at the grain boundary and at the grain matrix. The optical transmittance of the sample (5.0 mm thick) is 80.2% at 1064 nm. The lasing sample is Φ16.2 mm × 5.0 mm in size, mirror polished on both sides and without a coating. A laser diode (808 nm) was used as a pump source with a maximum output of about 1000 mW, and the end‐pumped laser experiment was demonstrated. With 658 mW of maximum absorbed pump power, a laser output of 8 mW has been obtained with a slope efficiency of 4.0%.

Fabrication, microstructure and properties of highly transparent Nd:YAG laser ceramics

Highly transparent 1.0 at%Nd:YAG laser ceramics were fabricated by solid-state reaction and vacuum sintering. The densification, the microstructure evolution, the optical, the mechanical and the thermal properties of the Nd:YAG ceramics were investigated. Fully dense Nd:YAG ceramic with average grain size of ∼15 μm was obtained by sintering at 1720 °C for 30 h. The grain boundary was clean and no secondary phase was observed. The in-line transmittance was 82.5% at 1064 nm. The absorption coefficients at 808 nm and 1064 nm were 4.52 cm −1 and 0.16 cm −1, respectively. The fluorescence spectrum for Nd:YAG ceramic was almost identical with single crystal and the fluorescent lifetime was 257 μs. With 341 mW of maximum absorbed pump power, laser output of 26 mW has been obtained with an oscillation threshold and a slope efficiency of 100 mW and 11.8%. The Vicker’s hardness, Young’s modulus, bending strength, fracture toughness values were 12.5 GPa, 221 GPa, 229 MPa and 2.21 MPa m 1/2, respectively. The thermal conductivity at room temperature was 9.7 W/m K and the average linear thermal expansion coefficient from 30 to 1000 °C was 8.713 × 10 −6 K.

Laser performance of monolithic Cr,Nd:YAG self-Q-switched laser

The self-Q-switched laser performance of monolithic Cr 4+,Nd 3+:YAG concave-planar resonator with 5-mm length was studied experimentally and theoretically. The slope efficiency is as high as 24% and pump threshold is as low as 64 mW. The pulse width, the single pulse energy and the pulse repetition rate of monolithic Cr,Nd:YAG self-Q-switched laser were measured as a function of absorbed pump power. With the increase of pump power, the pulse width decreases and the pulse energy and the pulse repetition rate increase. The average output power of 91 mW with pulse width of 7 ns at repletion rate of 35.5 kHz was obtained at the maximum absorbed pump power of 440 mW, the peak power is as high as 370 W. The theoretical prediction of pulse energy, pulse width and pulse repetition rate as a function of absorbed pump power based on rate equations is in a good agreement with our experimental data. This can lead to develop the diode laser-pumped monolithic self-Q-switched solid-state microchip lasers.