光学外差法测量Ba原子的自电离态

提出了把三光子共振非简并六波混频(NSWM)和双光子共振非简并四波混频(NFWM)应用于研究Ba原子自电离态的光学外差探测方法。采用该方法测量了Ba原子的6P_３／２19d自电离态，并观察到了三光子共振 NSWM和双光子共振NFWM信号干涉引起的信号增强。该方法是一种纯非线性光学方法，具有优秀的空间分辨率和简单的光路。其中双光子共振非简并四波混频信号作为本地振荡光束，三光子共振非简并六波混频信号作为信号光束，通过 改变信号光束的频率来达到用光学外差探测法研究Ba原子自电离态的目的。该方法中，实现相位匹配所要求的条件不是很严格，可以在很宽的频率范围内实现相位匹配，而一般的六波混频很难做到相位匹配, 并且所测量的信号是相干光， 当用窄带宽的激光时，可以获得消多普勒的分辨率。

Optics Heterodyne Detection of the Autoionization State of Barium

The autoionization state of barium was observed by optics heterodyne between three-photon resonant nondegenerated six-wave mixing(NSWM) and two-photon resonant nondegenerated four-wave mixing(NFWM).In this way,optics heterodyne spectrum of 6p3/219d autoionization state of barium was measured.The suppression and enhancement of the NFWM signal was observed which was caused by the quantum interference between NFWM and NSWM.Our method is a pure nonlinear optic technique.It has the advantages of excellent spatial signal resolution and simple optical alignment.Here two-photon resonant NFWM is used as local oscillation,while three-photon resonant NSWM signal is used as signal beam.Detection of autoionization states of Ba was achieved by changing the frequency of signal beam.The phase matching condition of this technique is not so stringent and can be achieved over a very wide frequency range,which is very difficult in the general six-wave mixing.Furthermore,the signal is coherent light.Optics heterodyne spectrum is a Doppler-free spectroscopy when the incident lasers have narrow bandwidths.