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Volume 96, Issue 3, 01 August 2004
- DEVICE PHYSICS (PACS 85)
All-optical light modulation in pharaonis phoborhodopsin and its application to parallel logic gates96(2004); http://dx.doi.org/10.1063/1.1765856View Description Hide Description
All-optical light modulation in pharaonis phoborhodopsin protein has been analyzed considering its state dynamics based on nonlinear intensity-induced excited-stateabsorption. Amplitude modulation of a cw probe laser beam transmission at corresponding to the peak absorption of intermediate state through , by a modulating cw pump laser beam at corresponding to the peak absorption of initial state has been analyzed considering all six intermediate states in its photocylce using the rate equation approach. The transmission characteristics have been shown to exhibit a dip at relatively lower pump intensity values compared to bacteriorhodopsin, which is sensitive to normalized small-signal absorption coefficient, rate constants of and states, and absorption of the state at . There is an optimum value of for a given pump intensity range for which maximum modulation can be achieved. It is shown that modulation can be achieved if the initial state of does not absorb the probe beam. The results have been used to design low power all optical parallel NOT, AND, OR, XNOR, and the universal NAND and NORlogic gates for two cases: (i) only changing the output threshold and (ii) considering a common threshold with different values. At typical parameters, wild-type based logic gates can be realized at considerably lower pump powers than .