摻釹與摻鐿雷射晶體在低溫下的自發輻射與受激輻射之研究

Abstract

我們以液態氮降溫的方式，觀察Nd:YAG、Nd:YAP、Nd:YLF、Nd:YVO4、Nd:GdVO4、Nd:LuVO4、Nd:KGW及Yb:KGW八種晶體在不同溫度下的自發輻射光譜峰值位置偏移、峰值強度等變化。發現在降溫過程中，有五種晶體發生原本較強之自發輻射峰值轉換至附近峰值的現象。並以Nd:YAG和Nd:YLF晶體為例，探討在不同輸入功率下，要達到雙波長雷射輸出功率相同之最佳溫度。其中以20 W之輸入功率，在溫度152 K，Nd:YAG晶體可達到1061 nm與1064 nm雙波長雷射輸出功率皆為6 W。以7.9 W之輸入功率，在溫度138 K，Nd:YLF晶體達到1047 nm與1053 nm輸出功率皆為1.55 W之雙波長雷射。

We explore the variation of the spontaneous emission spectra with temperature for eight gain media, including Nd:YAG, Nd:YAP, Nd:YLF, Nd:YVO4, Nd:GdVO4, Nd:LuVO4, Nd:KGW, and Yb:KGW crystals, as cryogenically cooling these gain media to 80 K. It is observed that the central peaks of the spontaneous emission spectra for five crystals shift to other side peaks with decreasing temperature. Moreover, we employ the Nd:YAG and Nd:YLF crystals to investigate the optimal temperatures for balancing the dual-wavelength output powers with the different incident pump powers. At an incident pump power of 20 W, the output powers of the Nd:YAG laser for the dual-wavelength at 1061 and 1064 nm can simultaneously reach 6.0 W at optimally balanced temperature of 152 K. At temperature of 138 K, the Nd:YLF laser can be operated at two wavelengths of 1047 and 1053 nm simultaneously with 1.55 W output power at an incident pump power of 7.9 W.