A simple high-power thin-disk pumping configuration using a radiation combination of four commercially available laser–diode stacks is introduced. Two setup modifications are presented to compensate the nonsuitable shape of the pumping spot arising from low beam quality in our combination method. The effects of setup modifications on pumping spot shapes are confirmed by ray tracing simulations using Trace-pro™ software. All setups are arranged in the laboratory, and the experimental measurements show pumping spots improvements on the disk due to modifications in agreement with simulation results. Output power measurements show that by adapting the pumping spot size to the disk cooling capacity the modified setups can deliver higher output powers and efficiencies. Furthermore, the modifications reduce the laser threshold and improve output laser beam quality. Hence, the modifications make the simple four laser–diodes beam combination applicable for thin-disk laser pumping.
The effect of directional image extension on the total pumping spot in thin disk lasers is reviewed. Three modified pumping setups that can compensate this effect and improve the absorption pumping area are presented, and the efficiency, advantages, and disadvantages of each modified configuration are discussed. Numerical comparison between absorption intensity profiles confirms an increment of maximum pump absorption density at the central region of the pumping area with respect to normal setup. Experimental investigation for the last modified pumping arrangement is in good agreement with simulation results. Measuring laser power output with a similar simple I-shaped resonator shows an enhancement of slope efficiency up to 2.5% together with a lower laser threshold for our modified setup.
In this paper we have investigated three wave interaction analytically for stimulated Raman back-scattering in resonance
and non-resonance conditions in an under dense plasma. We have solved equations by similarity transformations and
have found self similar solutions. It has been shown that by increasing time, maximum of amplified pulse increase
constantly while the duration decrease inversely. Effects of initial seed pulse’s amplitude and detuning parameter have
been investigated.
KEYWORDS: Ions, Plasma, Systems modeling, Laser systems engineering, Temperature metrology, Ionization, Hydrogen, Chemical species, Oscillators, Physics
Population densities for the excited levels of hydrogen-like ions in an optically thin plasma have been calculated in
order to investigate the appropriate conditions for the generation of population inversion by recombination and
subsequent development of gain in laser systems. To achieve this goal, collisional-radiative model in a range of electron
temperature of 4000Z2 - 256000Z20K and electron density of 108 Z7 - 1018 Z7 cm-3 is used. In addition, the inversion
threshold temperature is introduced and used in characteristic graphs which helps to identify the inversion conditions.
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