Study on influence of pumping spectrum on stable uniform pumping in a side-pumped Nd:YAG amplifier

A new method to realize temperature-stable uniform pumping was presented. Concept of effective absorption coefficient is introduced at first, which is used to indicate actual absorption coefficient of Nd:YAG working materials that concerned the influence of laser diode pumping spectrum characters. After this, flattop and Gaussian as a typical pumping spectrum shaping are discussed, and experimental measured laser diode spectrum is also used to calculate effective absorption coefficient as a comparison. Next, experimental results of pump laser diode deviating from absorption peak of neodymium ion are also numerical analysed, and these results are used to guide pumping central wavelength control. Finally, an optimized laser diode pumping spectrum shape is put forward. With such a pumping spectrum shape, effective absorption spectrum can be optimized to flattop shape, and temperature-stable uniform pumping can be realized.