Two-photon resonant NFWM is a Doppler-free spectroscopy by using the narrow bandwidth of incident laser beams.
当用窄带宽的激光时，该技术对里德堡能级的窄光谱结构可以获得消多普勒的分辨率。
The high resolution spectrum can be obtained through many methods, such as saturated absorption spectroscopy, Doppler free methods of two-photon spectroscopy, and etc.
提高热原子光谱的分辨率可以有许多方法，如饱和吸收光谱技术、双光子光谱的消多普勒技术等。
The high resolution spectrum can be obtained through many methods, such as saturated absorption spectroscopy, Doppler free methods of two-photon spectroscopy, and etc.
提高热原子光谱的分辨率可以有许多方法，如饱和吸收光谱技术、双光子光谱的消多普勒技术等。
应用推荐