利用微波场抑制电磁感应透明的功率展宽

电磁感应透明的重要参量之一是透明窗口的光谱线宽。在Λ-型三能级原子系统中,电磁感应透明的光谱线宽由两低能级间的相干失相速率决定,若两低能级同属于原子基态的精细结构,则电磁感应透明窗口的极限线宽很窄。但较强的耦合场作用往往会导致电磁感应透明窗口的功率展宽,而减弱耦合场又会影响电磁感应透明的对比度和深度。为此,通过引入微波控制场共振作用于基态精细能级间构成三场作用下的准Λ-型四能级系统,利用微波控制场来抑制耦合场所引起的电磁感应透明窗口的功率展宽。结果表明,引入微波控制场不仅得到了双窗口电磁感应透明,而且在保持较好对比度的条件下,使得电磁感应透明的光谱线宽明显小于不加微波场的情况。

Suppressing Power Broadening of Electromagnetically Induced Transparency by Utilizing Microwave Field

One of the most interesting properties of the EIT is that its linewidth can be extremely narrow in a A-type configuration where two lower levels are hyperfine ones within a ground state, In such a configuration, the EIT linewidth is mainly governed by the coherence relaxation rate between hyperfine levels which can be of several orders of magnitude smaller than that of the optical transition. However, As intensity of coupling field increases, the EIT linewidth can be broadened. In order to control power broadening of EIT, we present a quasi-A four-level system, and introduce an microwave field to drive a hyperfine transition. It is shown that the microwave field not only splits an EIT window into a doublet but also narrows the EIT window. Power broadening of EIT window can be suppressed by utilizing a microwave field.