Coherence-driven gain and its possible measurement in pump–probe experiments

✍ Scribed by F.B. de Jong; B.T. Wolschrijn; R.J.C. Spreeuw; H.B. van Linden van den Heuvell

• Book ID: 104161248
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 282 KB
• Volume: 179
• Category: Article
• ISSN: 0030-4018
• DOI: 10.1016/s0030-4018(99)00717-8

✦ Synopsis

We discuss the phenomenon of coherence-driven gain: the effect that oscillating atomic dipoles can amplify or attenuate a light field depending on the phase difference between dipoles and field. No inversion of atomic population is required to increase the field. This is in contrast to population-driven gain where an inverted atomic medium always contributes to gain, regardless of the phase of the light field. In particular, we discuss coherence-driven gain in two-level systems and wave-packets. We present gedanken experiments in an attempt to separate the phase-dependent gain from modifications of the probe pulse shape caused by the coherent pump mechanism. Experiments on electronic wave-packets in Nd:YAG are presented as an illustration. We also performed experiments using short optical pulses to excite etalon modes. These optical pulses mimic the wave-packet dynamics of matter. The experiments offer a clear interpretation of coherence-driven gain and lead to an analogy with interference on a beamsplitter and homodyne detection.