Open AccessCoherent population oscillations and superluminal light in a protein complex
Author(s) -
Chandra S. Yelleswarapu,
Samir Laoui,
Reji Philip,
D. V. G. L. N. Rao
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.003844
Subject(s) - superluminal motion , optics , physics , wavelength , saturable absorption , population , pulse (music) , modulation (music) , absorption (acoustics) , signal (programming language) , quantum mechanics , fiber laser , demography , sociology , detector , computer science , acoustics , programming language
We observed superluminal light in aqueous solution of the protein complex bacteriorhodopsin (bR) at 647.1 nm wavelength where it exhibits reverse saturable behavior, exploiting the technique of coherent population oscillations (CPO). With a modulation frequency of 10 Hz, the signal pulse through a 1 cm path cell is ahead by 3 msec relative to the reference pulse, corresponding to a group velocity of -3.3 m/sec. Following our early work on slow light in the same sample at the saturable wavelength 568.2 nm, we now explicitly observed the narrow spectral hole in the absorption band of the stable B state and further, demonstrated a close correlation between the profile of the hole and the corresponding pulse delay for various modulation frequencies. A similar behavior is observed for superluminal light versus antihole blown in the absorption band.