电磁诱导透明(EIT)和电磁诱导吸收(EIA)是光与物质相互作用中表现出来的奇特的非线性效应，对其形成机理及非线性特性的研究具有重要的理论意义和巨大的潜在应用价值。构建一个闭合Λ型四能级系统包括两个基态精细结构能级和两个激发态精细结构能级，除耦合场和探测场外，还附加了两个射频场分别作用于激发态精细结构能级和基态精细结构能级之间。为了讨论耦合场失谐对系统的影响规律，采用的两个射频场分别与对应能级共振。通过求解系统的密度矩阵方程组，发现该系统中同时出现了EIT和EIA，而且调谐耦合场的频率失谐量可以控制EIT或EIA的频率位置和非线性特性。

Electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) are intriguing nonlinear phenomena of light-atom interaction. The study on their nonlinear behaviors has theoretical significance and potential applications. A closed-lambda four-level system consisting of hyperfine levels of excited state and those of ground state is proposed. In addition to a coupling field and a probing field, there are two radio-frequency fields which interact with hyperfine levels of excited state and those of ground state, respectively. In order to focus on detuning effect of the coupling field on the system, two resonant radio-frequency fields are used. By solving the equations of density matrix motion, both EIT and EIA are obtained in the system, and the frequency and feature of EIT or EIA are controlled by tuning the detuning of coupling field.