Characterisation of Long M-State Lifetime Bacteriorhodopsin Thin Films for Optical Cache Memory

概要

論文の詳細を見る
We report the optical characterisation of bacteriorhodopsin (BR) films of long intermediate-state lifetimes. The M-state lifetime is extended from 10 ms for the native BR protein to 〜20 minutes for our BR films, by chemical and physical modifications of the material. Optical cache memory characteristics of thin films are studied in excite-probe experiments in which nanosecond-duration pulses are used to excite a BR film and cw monochromatic light used to monitor the transmission dynamics. The memory read-time is found to vary significantly with the probe wavelength; it is of the order of milliseconds at 633 nm and of the order of 100 μs for probe wavelengths of 600 nm and below. The memory erase-time is 〜50 μs. Contrast ratios and insertion losses are measured at different probe wavelengths, with a maximum contrast ratio following nanosecond excitation of 〜3:1 obtained in the peak absorption region of the B-state (〜57O nm), at an excitation fluence of 30 mJcm^<-2>. The implications of these results for the application of BR films as optical cache memory devices are discussed.
社団法人応用物理学会の論文
1997-01-30