All-optical sub-ps switching and parallel logic gates with bacteriorhodopsin (BR) protein and BR-gold nanoparticles

作者：Roy Sukhdev^*; Yadav Chandresh

来源：Laser Physics Letters, 2014, 11(12): 125901.

DOI：10.1088/1612-2011/11/12/125901

• ultrafast nonlinear optics
• optical logic
• all-optical devices
• all-optical switching
• bacteriorhodopsin
• nanomaterials
• ultrafast information processing

We propose a model for the early sub-picosecond (sub-ps) transitions in the photochromic bacteriorhodopsin (BR) protein photocycle (B-570 -> H -> I-460 -> J(625) -> B-570) and present a detailed analysis of ultrafast all-optical switching for different pump-probe combinations. BR excitation with 120 fs pump pulses at 570 or 612 nm results in the switching of cw probe beams at 460 and 580 nm exhibiting reverse saturable absorption (RSA) and saturable absorption (SA) respectively. The effect of pump intensity, pump pulse width, lifetime of I-460 state, thickness and concentration on switching has been studied in detail. It is shown that low intensity (MW cm(-2)), high contrast (100%), sub-ps all-optical switching can be achieved with BR-gold nanoparticle solutions. The validity of the proposed model is evident from the good agreement of theoretical simulations with reported experimental results. The switching characteristics have been optimized to design ultrafast all-optical parallel NOT, OR, AND and the universal NOR and NAND logic gates. High contrast, ultrafast switching at relatively lower pump intensities, compared to other organic molecules, opens up exciting prospects for ultrafast, all-optical information processing with BR and BR nano-biophotonic hybrid materials.

• 出版日期2014-12