Fast energy transfer in green photosynthetic bacteria studied by spectral hole burning

T. P. Carter, Christof Bräuchle, V. Y. Lee +2 more

P. J. van der Zaag, Thomas Schmidt, H. Van Der Laan +2 more

Permanent and transient hole-burning experiments carried out on various types of amorphous systems at temperatures between 0.3 and 20 K are presented. Optical dephasing on organic molecules in glasses and polymers measured on different time scales are discussed in relation to spectral diffusion processes and compared to the literature. The pure dephasing time appears to be proportional to the excited state lifetime of the guest. Organic molecules adsorbed on the surface of porous silica glass show that their homogeneous linewidth is an order of magnitude larger than in polymers and glasses in the bulk, but follows the same temperature dependence. Hole-burning results on bacteriochlorophyll in various disordered hosts are compared to those on a isolated light-harvesting photosynthetic pigment-protein complex (B800–850). From the holewidth in the latter the energy transfer rate between aggregated bacteriochlorophyll pigments is determined and compared to time-resolved spectroscopy results in the literature.

Omar Gamel, C. H. Herman Chan, Graham R. Fleming +1 more

Rajitha Papukutty Rajan, Aleksander K. Rebane, Hans Riesen

The generation of slow and fast light in the same transient hole-burning experiment by two laser-frequency modulation methods is reported. The schemes allow for rapid switching between slow and fast light on very short time scales. Experiments were carried out in the R1(±3/2) line of a pale green (0.04 wt. % Cr) emerald, Be3Al2Si6O18:Cr3+ in π polarization (E∥c) at 2.3 K in a low magnetic field B∥c of 12 mT. Maximum delays and advancements for a 115 ns Gaussian pulse were 65 and −25 ns, respectively, corresponding to group indices of 7.8·103 and −3·103. The present schemes point to possible applications in all-optical switches.

Yuta Mitome, Satoshi Iriyama, Keiko Sato +1 more

Hans Riesen, Aleksander K. Rebane

Slow light effects induced by transient spectral hole-burning in the 7 F 0 → 5 D 0 transition of Sm 2+ in BaFCl at 688 nm are reported and a probe pulse delay of 1.25 μ s was observed through a 5 mm thick crystal. This delay corresponds to a reduction of the group velocity v G of the transmitted light to ∼4000 m/s. An analysis of the dependence of the slow light effect on the probe pulse timing indicates some broadening of the spectral hole caused by relatively fast excitation energy transfer. We also demonstrate two-pulse (2PE) and (three-pulse) stimulated photon echoes (SPE) for the first time for Sm 2+ in the solid state and a homogenous linewidth of 16 kHz (∼2.5·10 −8 nm) was obtained at 1.8 K. The echoes in the optically dense medium were very efficient and revealed spectral diffusion on the 100- μ s time scale possibly due to flipping of the fluorine and chlorine nuclear spins in the environment of the Sm 2+ ions. Furthermore, the SPE also indicates relatively fast energy transfer, commensurate with the hole decay.