Abstract
We observe that the group velocity of light is reduced to an extremely low value of in a biological thin film of bacteriorhodopsin at room temperature. By exploiting unique features of a flexible photoisomerization process for coherent population oscillation, the velocity is all-optically controlled over an enormous span, from snail-paced to normal light speed, with no need of modifying the characteristics of the incident pulse. Because of the large quantum yield for the photoreaction in this biochemical system, the ultraslow light is observed even at low light levels of microwatts, indicating high energy efficiency.
- Received 17 May 2005
DOI:https://doi.org/10.1103/PhysRevLett.95.253601
©2005 American Physical Society