The phase dependent properties of gain and absorption in an Er3+-doped yttrium aluminum garnet crystal

We theoretically study the phase dependent gain–absorption properties in an Er3+-doped yttrium aluminum garnet crystal. We show that the phenomenon of flattened gain (absorption) can be achieved in a closed three-level system when the total interaction phase equals to π/2 (3π/2). We also can realize a flexible control of the gain equalization with different amplitudes and frequency regions by varying intensities of strong coupling fields. In particular, we point out that the Raman gain always plays an important role in achieving and controlling the flattened gain.