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Semiconductor diode sided pumped Nd: YAG solid laser can achieve higher power output. However, because of the characteristic of semiconductor and crystal, we need temperature controlling and active cooling system. And those systems cause it is hard to minimize the volume, weight and power dissipation. In this article, we use two absorption peak, 796 and 808nm, of Nd: YAG crystal to compose multiwavelength cooling-free array with three different wavelength diodes. It can be used in wide temperature range and solve those problem effectively.
Use Matlab to calculate the result with two different conditions. One condition is that the average power absorption efficiency is higher than 40%, the temperature is from -55 to 60°C and the variance is lower than 4%. This condition is calculated for wide temperature range. The other condition is that the average power absorption efficiency is higher than 50%, the temperature is from -30 to 30°C and the variance is lower than 7%. This condition is prepared for higher absorption. For each group, choose three best wavelength automatically, then change the wavelength difference between middle wavelength and others. By doing those calculation, we can simulate the process tolerance in production and get the best result. Finally, we use GaAsP/InGaP/InGaAlP strain quantum well material of light and electron limited respectively, and 1mm cavity length with high fill factor. Besides, we also use different coatings to change center wavelength lightly and package with high efficient cooling to make sure the uniformity. As a result, we get an array pumped source of multiwavelength and temperature control-free which has difference of center wavelength lower than ±0.8nm, and its FWHM (full width half maximum ) is 3.5±0.5nm. Simulation results of spectrum is conformed to the actual test results.
The best wide temperature range has three wavelength combinations of 786nm, 805nm and 811nm @25°C. The variance of hole temperature is 3.92% and the average power absorption is 41.99%. Besides, the best higher power absorption result is three different wavelength of 806, 811, 815nm @25°C. The variance of hole temperature is 4.78% and the highest power absorption is 52.68%. Those two simulations agree with the actual test result and get good feedback from users.
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