All-optical switching in LOV2-C250S protein mutant from Chlamydomonas reinhardtii green algae

We theoretically analyze all-optical switching in the Phototropin mutant LOV2-C250S of the LOV2 domain from Chlamydomonas reinhardtii phot protein, based on nonlinear intensity-induced excited-state absorption. The transmission of a cw probe laser beam at 715 nm corresponding to the peak absorption of the first excited L-state, through the LOV2 sample, is switched by a pulsed pump laser beam at 442 nm that corresponds to the maximum initial D state absorption. The switching characteristics have been analyzed using the rate equation approach, considering the two intermediate states and transitions in the LOV2 photocycle. We report a comparative study of the switching response of this genetically modified protein-mutant LOV2-C250S with the wild-type LOV2 and present designs for all-optical logic gates. The switch-off and on time is 3.1 and 28.58 ¿s. All-optical switching in this mutant is faster than the wild-type. It shows the possibility of optimizing the photoresponse by genetic engineering for faster all-optical biomolecular computing.