Generation of single-frequency tunable vacuum ultraviolet laser radiation in solid hydrogen

本项目的目的是利用固体氢作为一种非线性光学材料，在真空紫外线(VUV)区域实现有用的相干辐射。我们尝试在固体氢气中有效地调制200 nm附近具有极高拉曼相干的单频可调谐激光辐射，并在真空紫外区产生单频可调谐激光辐射。在以下内容中，我们总结了我们的主要结果：1.采用266 nm和827 nm(钛宝石激光的四次谐波)激光辐射产生了201 nm激光辐射，能量转换效率约为10%。产生的201 nm激光的脉冲宽度为10 ns，傅里叶变换的极限线宽为30 MHz。2.我们在固体氢气中绝热驱动的125太赫兹的喇曼相干调制了单频可调谐201 nm激光辐射，得到了186 nm的真空紫外相干辐射，量子效率约为8%。3.我们在真空紫外区展示了(B^3Σ_&lt；-u&gt；(v‘=8，N’=20)←X^3Σ_&lt；-g&gt；(v“=0，N”=19)，波长：185.987 nm)。我们已经证明了在真空紫外区获得光谱分辨率为~50 MHz的激光光谱是可能的，从而获得了这一跃迁的精确光谱轮廓和截面。

The purpose of the present project is to realize useful coherent radiations in vacuum ultraviolet (vuv) region using solid hydrogen as a nonlinear optical material. We have tried to efficiently modulate single-frequency tunable laser radiations around 200 nm with extremely high Raman-coherence in solid hydrogen and generate single-frequency tunable laser radiations in vuv region. In the following, we summarize our principal results.1, We have generated 201nm laser radiation by taking sum-frequency of 266nm- (forth harmonics of YAG laser) and 827nm- (Ti : sapphire laser) laser radiations with energy conversion efficiency of 〜10%. The pulse duration of the generated 201 nm laser radiation was 10 ns with the Fourier transform limited linewidth of 〜 30 MHz.2, We have modulated the single-frequency tunable laser radiations at 201 nm by the Raman-coherence with the frequency of 125 THz that was adiabatically driven in solid hydrogen, leading vuv coherent radiation at 186 nm with quantum efficiency of 〜 8%.3, We have demonstrated laser spectroscopy in vuv region for a transition in Schumann-Runge band (B ^3Σ_<-u> (v'=8, N'=20) ←X ^3Σ_<-g> (v"=0, N"=19), wavelength : 185.987nm) by using the coherent vuv radiation realized above. We have shown that the laser spectroscopy with spectral resolution of 〜 50 MHz is possible in vuv, leading the precise spectral profile and cross section of this transition.