Transient gain-absorption of the probe field in asymmetric semiconductor quantum wells

Under the weak-probe approximation, we theoretically investigate the transient gain-absorption property of the probe field in a four-level asymmetric semiconductor quantum well system. We find that the strength of Fano interference and the energy splitting affect the transient gain-absorption property of the weak continuous-wave (CW) probe field or Gaussian-pulse probe field dramatically. The dependence of transient gain-absorption property of the probe field on the intensity and the frequency detuning of the strong coupling field is also given. Our study is much more practical than its atomic counterpart due to its flexible design and the controllable interference strength. Thus, it may provide some new possibilities for technological applications.