Propagation of a weak probe pulse through a $\Lambda$ system in a resonant gain configuration is investigated. We employ the control field intensity that permits the amplification of probe pulse during propagation, without instability at two photon resonance. Posterior to amplification, a broadened probe pulse is obtained, which retains its initial pulse shape and travels at the speed of light in vacuum without experiencing any delay, absorption, and dispersion. The salient feature of this technique lies in the fact that in addition to preserving the initial pulse shape, it also ensures stable pulse propagation after amplification. It also works for arbitrary probe pulse shapes.

中文翻译：

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保形原子脉冲放大器

研究了弱探测脉冲在谐振增益配置中通过$\Lambda$系统的传播。我们采用控制场强度，允许在传播过程中放大探测脉冲，而不会在两个光子共振时不稳定。在放大之后，获得加宽的探测脉冲，该脉冲保持其初始脉冲形状并在真空中以光速传播，没有任何延迟、吸收和色散。该技术的显着特点在于，除了保持初始脉冲形状外，还确保放大后的稳定脉冲传播。它也适用于任意探测脉冲形状。