It has been demonstrated experimentally that pulsed pumping can significantly improve the thermal management in an optically-pumped semiconductor disk laser, and the output power of semiconductor disk lasers under pulsed pumping can be upgraded to times of those under continuous pumping. This paper presents numerical analysis of the thermal effects of pulsed pumping in semiconductor disk lasers, so to theoretically disclose the details of the thermal processes of pulsed pumping. In the simulation, the parabolic heat conduction equation, which is widely employed to describe the transient thermal transfer processes, is solved under cylindrical coordinates by the use of the finite element method, a periodic pump pulses train is assumed, and the maximum temperature rise in the multiple quantum wells active region is focused. The influences of the duty cycle, the repetition rate, and the pulse width of the pump pulses on the maximum temperature rise are investigated, and the results are compared with the case of continuous-wave pumping. Some simulation results are compared with reported data, and the theoretical results are in good agreement with the experiments.
On the basis of the analysis of material gain, a comprehensive optimization of quantum wells used in a 1-μm vertical-external-cavity surface-emitting laser was carried out. For a single-well structure, the optimized width lies between 8 and 10 nm, the optimized depth is a quantum well with ∼0.1 Al composition in AlGaAs barrier, and the optimized configurations are graded-index quantum well and quantum well with AlGaAs barrier and a GaAs buffer layer. The optimal width of a double- or triple-well structure lies between 6 and 8 nm. Compared to its single- and triple-well counterparts, double-well structure provides higher gain and has more tolerance to the deviation of laser wavelength.
The lithography ion-exchange method of producing the gradient index micro-cylinder lens with gradual focus is
presented. The lens is developed for the coupled shaping of the pump beam of side-pumped disk fiber laser, its main
purpose is to make the LD beam which coupled into the ring disk container and the radial of the ring disk container have
a certain angle, and ensure that all the pump beams couple into the interior of the ring disk container through the thin slit
of the side. The micro-cylinder lens with different shapes can be obtained by the special designs of ion-exchange
windows. The focused spot of the parallel beam passed through the lens is a special curve with required setting.
Consequently, the lens also adapt to other applies with gradual focus. The experimental results coincide with the design.
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