Influence of pump beam size on laser diode end-pumped solid state lasers |
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Authors: | Wenjie Xie Siu-Chung Tam Yee-Loy Lam Hongru Yang Jianhui Gu Gang Zhao Wilson Tan |
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Institution: | a Photonics Research Group, School of Electrical and Electronic Engineering Nanyang Technological University, Nanyang Avenue, S639798, Singapore b Chartered Electro-Optics Pte Ltd, Singapore |
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Abstract: | Based on space-dependent rate equation, the lowest threshold input power for diode end-pumped solid state lasers is obtained for pump spot size wp → 0. However, when the pump beam waist is decreased, the far-field half-angle increases due to the same beam quality, which will influence the match between the pump volume and mode volume. Most importantly, when the pump beam waist is decreased, the temperature and temperature gradient in the laser rod would be very high due to the resulting heat, which would cause material distortion, variation of refractive index, instability of laser resonator etc. We analyze the temperature distributions with different pump beam sizes and conclude that the condition wp ≈ w0 (the radius of the laser beam at the laser rod) is often taken as a rough guide to the optimum case. |
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Keywords: | Thermal effects Lasers Solid state lasers |
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