Enhancement of speed of digital operation in bacteriorhodopsin based photonic switch

Photonic spectral modulation in bacteriorhodopsin molecules and optimization of signal wavelength

“…The dip i.e. low transmission region appears due to high absorption of signal beam by dark adopted B-state, as all BR molecules stay in the B-state in the absence of modulating light [4][5][6][7][8][9]. Increase in I m , modulates T(I m , ) curve.…”

“…all-optical light modulation or photonic modulation [1][2][3][4]. BR exhibits large absorption changes in the entire visible region, and hence, can be utilized for nonlinear absorption based photonic modulation devices [4][5][6][7][8][9]. In addition, large number of intermediates with different spectral and kinetic behavior provide an excellent opportunity of controlling nonlinear absorption properties i.e.…”

“…Most of the photonic applications of BR are proposed considering operating wavelengths either corresponding to peak absorption of its longerlived intermediates, or conveniently obtained from various types of lasers [1][2][3][4][5][6][7][8][9][10][11][12][13][14], which may not result maximum modulation due to large overlap and complexity of its intermediates spectra. To the best of our knowledge, a very important aspect, optimization of operating wavelengths in the intensity-induced nonlinear absorption based photonic devices of BR, has not been explored so far.…”

“…Considering the six states in the typical wild type BR (WT-BR) photocycle, the six rate equations can be written as [4][5][6][7][8],…”

Effect of probe beam intensity on all-optical switching based on excited-state absorption

“…Of the wide variety of materials studied for all-optical switching, naturally occurring photosensitive biomolecules optimized over centuries of evolution, whose spectral and kinetic properties can be tailored through physical, chemical and genetic engineering, appear to be quite fascinating. The large family of rhodopsin proteins exhibits an efficient photoresponse, with the photochromic Bacteriorhodopsin (bR) protein found in the purple membrane of Halobacterium halobium having attracted most attention for bio-molecular photonic applications [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Recently, a new blue-shifted photoreceptor sensory rhodopsin II (sRII) or phoborhodopsin (pR) like protein, synthesized from Natronobacterium pharaonis, a halophilic alkaliphilic bacterium termed pharaonis phoborhodopsin (ppR), has received much attention due to its good stability and recent structure elucidation [36][37][38].…”