Lab Chip 2016[Jun]; 16 (12): 2228-35 PMID27220992show ga
Chlorophylls are essential for photosynthesis and also one of the most abundant pigments on earth. Using the optofluidic ring resonator of extremely high Q-factors (>107), we investigated unique characteristics and the underlying mechanism of chlorophyll lasers. The chlorophyll lasers with dual lasing bands at 680 nm and 730 nm were observed for the first time in isolated chlorophyll a (Chla). Particularly, laser at the 730 nm band was realized in 0.1 mM Chla with a lasing threshold of only 8 ?J/mm2. Additionally, we observed lasing competition between the two lasing bands. The presence of the laser emission at the 680 nm band can lead to quenching or significant reduction of laser emission at the 730 nm band, effectively increasing the lasing threshold for the 730 nm band. Further concentration dependent studies, along with the theoretical analysis, elucidated the mechanism that determines when and why the laser emission band appears at one of the two bands, or concomitantly at both bands. Finally, Chla was exploited as the donor in fluorescence resonance energy transfer to extend the laser emission into the near infrared regime with an unprecedented wavelength shift as large as 380 nm. Our work will open a door to the development of novel biocompatible and biodegradable chlorophyll based lasers for various applications such as miniaturized tunable coherent light sources and in-vitro/in-vivo biosensing. It will also provide important insight into the chlorophyll fluorescence and photosynthesis processes inside plants.
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Lab+Chip 2016 ; 16 (12): 2228-35
