Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030, USA.
Opt Lett. 2011 Aug 15;36(16):3130-2. doi: 10.1364/OL.36.003130.
We present a five-level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the atoms with a control laser and rf/microwave fields. By weak incoherent pumping of the population into a single metastable state, one can create several narrow amplifying resonances. At frequencies between these gain lines and additional absorption lines, there exist regions of vanishing absorption but resonantly enhanced index of refraction. In Rb vapors with density N in units of cm(-3), we predict an index of refraction up to n≈√(1+1.2×10(-14)N) for the D1 line, which is more than an order of magnitude larger than other proposals for index of refraction enhancement. Furthermore, the index can be readily reduced below 1 by simply changing the sign of the probe or rf field detunings. This enhancement is robust with respect to homogeneous and inhomogeneous broadening.
我们提出了一个五能级原子系统，在这个系统中，通过用控制激光和射频/微波场对原子进行“ dressing ”，可以在吸收和增益线对之间的区域将探针激光的折射率增强或降低到小于 1，同时吸收可以忽略不计。通过将原子的布居数弱非相干地泵浦到一个单亚稳态中，可以产生几个窄的放大共振。在这些增益线和附加吸收线之间的频率处，存在吸收为零但折射率共振增强的区域。在密度为 N 的铷蒸气中（以 cm(-3)为单位），我们预测 D1 线的折射率高达 n≈√(1+1.2×10(-14)N)，比其他折射率增强方案大一个数量级以上。此外，通过简单地改变探针或射频场失谐的符号，折射率很容易降低到 1 以下。这种增强对均匀和非均匀展宽都是鲁棒的。
