Measurements of photoinduced refractive index changes in bacteriorhodopsin films

Abstract

We report the pump-probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive index changes are studied using a probe beam at 633 nm. The proposed technique is based on a convenient and accurate determination of optical path difference using digital interferometry-based local fringe shift. The results are presented for the wild-type as well as genetically modified D96N variant of the bacteriorhodopsin.

Nonlinear Optical Investigation of Microbial Chromoproteins

“…1, our goal was to compare our measured n 2 values with those in the literature and to provide for us benchmark values for the investigation of PYP (see section "Nonlinear Refractive Index of PYP"). Our measured n 2 values in the average intensity range of 10 −2 to 10 2 W/cm 2 fall in the range of 10 −1 to 10 −5 cm 2 /W ( Figure 8A) in agreement with the literature on bR excited in the green spectral range by CW lasers (Song et al, 1993;Kir'Yanov et al, 2000;Sifuentes et al, 2002;Banyal and Raghavendra Prasad, 2007). The increasing gap with increasing average intensity between the n 2 values measured with a CW and a pulsed laser may suggest that further processes, other than a simple cubic nonlinearity are at play, such as thermal effects, thermally induced conformational changes, and refractive or absorptive nonlinearities of higher order.…”

Measurement of the nonlinear refractive index of 2, 5-dimethylaniline by a new technique using Mach–Zehnder interferometer

“…26,27 Study of third order nonlinearity was accomplished by pump-probe arrangement in Mach-Zehnder interferometer. 28,29 Moran et al proposed a scheme using time resolved Mach-Zehnder intereferomtric measurement to characterize the third order susceptibility of laser system materials relative to CS 2 . 30 In the present work a new scheme has been proposed which is based on the Mach-Zehnder interferometer.…”