Abstract:A gain slab configuration with a low thermally induced wavefront distortion, which is based on heating the edge by the cladding layer, is proposed. The gain slab will be applied to a helium-cooled Nd: glass multislab laser amplifier with an output of 100 J at a repetition rate of 10 Hz. Additionally, a 3D numerical simulation model is developed to analyze the thermo-optic effects in the gain slab. Some parameters, including the absorption coefficient (α) of the cladding layer, the shape of the pump beam, and t… Show more
A systematic design of a 100 J/10 Hz multislab Nd:glass laser amplifier is proposed. A four-dimensional numerical model was developed for exploring the influence of amplified spontaneous emission (ASE) on the stored energy of the laser amplifier. The influences of different parameters, including the doping concentration of the gain slab, pump pulse duration (
T
p
u
m
p
), and pump energy density (
E
p
) absorbed in the gain slab, on the stored energy and storage efficiency were studied in detail. Furthermore, the uniform distribution of the stored energy for a larger aperture of the gain slab and a higher pump energy density of the laser amplifier was determined. In addition, the effects of the slab-to-slab transfer of ASE rays on the stored energy were explored. The results show that the distributions of the stored energy for the 100 J/10 Hz laser amplifier were uniform; furthermore, an average storage efficiency of 60.87% was obtained when the pump energy density absorbed in each slab was
0.9
J
/
c
m
3
and the pump duration was 300 µs.
A systematic design of a 100 J/10 Hz multislab Nd:glass laser amplifier is proposed. A four-dimensional numerical model was developed for exploring the influence of amplified spontaneous emission (ASE) on the stored energy of the laser amplifier. The influences of different parameters, including the doping concentration of the gain slab, pump pulse duration (
T
p
u
m
p
), and pump energy density (
E
p
) absorbed in the gain slab, on the stored energy and storage efficiency were studied in detail. Furthermore, the uniform distribution of the stored energy for a larger aperture of the gain slab and a higher pump energy density of the laser amplifier was determined. In addition, the effects of the slab-to-slab transfer of ASE rays on the stored energy were explored. The results show that the distributions of the stored energy for the 100 J/10 Hz laser amplifier were uniform; furthermore, an average storage efficiency of 60.87% was obtained when the pump energy density absorbed in each slab was
0.9
J
/
c
m
3
and the pump duration was 300 µs.
The good cladding of a large-sized Nd-doped phosphate glass slab as a laser amplifier requires not only the amplified spontaneous emission and parasitic oscillation to be fully absorbed, to hold up the small signal gain coefficient of the Nd ions, but also the absorbed heat energy to be appropriately dissipated to extend a uniform temperature field for the larger laser beam aperture of the edge-cladded Nd–glass slab. In the present work, numerical simulations were performed based on the developed feasible edge-cladding designs for a 786 × 436 × 40 mm3 Nd–glass slab, including the following alterations: optical absorptivity, quantum-dot absorption centers, ceramics with higher thermal diffusivity, glasses with lower and higher specific heat values, 3D printing edge-cladding methods, double-deck edge-cladding structure with transparent strips as a buffer layer, and thickening of the edge-cladding. All of these designed edge-cladding materials, methods, and structures satisfy both requirements of sufficiently absorbing and precisely matching with the refractive index, as emphasized by the edge-cladding for the Nd–glass. Some of the designed edge-claddings resulted in a much more uniform temperature field than the composite polymer–glass edge-cladding as the standard for comparison, which could be utilized to extend the effective laser aperture of the Nd–glass slab, thus being beneficial to the laser beam size and laser energy in the optics recycle loop strategy.
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