Beijing Computational Science Research Centre, Beijing 100084, China.
Phys Rev Lett. 2013 Mar 1;110(9):093901. doi: 10.1103/PhysRevLett.110.093901. Epub 2013 Feb 25.
Optical diodes controlling the flow of light are of principal significance for optical information processing. They transmit light from an input to an output, but not in the reverse direction. This breaking of time reversal symmetry is conventionally achieved via Faraday or nonlinear effects. For applications in a quantum network, features such as the abilities of all-optical control, on-chip integration, and single-photon operation are important. Here we propose an all-optical optical diode which requires neither magnetic fields nor strong input fields. It is based on a "moving" photonic crystal generated in a three-level electromagnetically induced transparency medium in which the refractive index of a weak probe is modulated by the moving periodic intensity of a strong standing coupling field with two detuned counterpropagating components. Because of the Doppler effect, the frequency range of the crystal's band gap for the probe copropagating with the moving crystal is shifted from that for the counterpropagating probe. This mechanism is experimentally demonstrated in a room temperature Cs vapor cell.
光学二极管控制光的流动对于光信息处理具有重要意义。它们将光从输入传输到输出,但不能反向传输。这种时间反转对称性的破坏通常通过法拉第或非线性效应来实现。对于量子网络中的应用,全光控制、芯片集成和单光子操作等功能非常重要。在这里,我们提出了一种全光学二极管,它既不需要磁场也不需要强输入场。它基于在三能级电磁感应透明介质中产生的“移动”光子晶体,其中弱探针的折射率通过强驻波耦合场的移动周期性强度调制,该强驻波耦合场具有两个失谐的反向传播分量。由于多普勒效应,与移动晶体共线传播的探针的晶体带隙的频率范围从与反向传播探针的频率范围偏移。该机制在室温 Cs 蒸汽室中得到了实验验证。