We quantify and ascertain the nature of the second-harmonic generation (SHG) response of amphiphilic push–pull chromophores to a transmembrane electric field. Our technique is based on the application of an alternating field across labeled giant unilamelar vesicles. For chromophore responses that are purely electro-optic, our technique provides an estimate of photoinduced charge shifts based on the observed dispersion of the field response, in accord with a two-level perturbation theory. These results are applicable to the optimization of membrane potential sensors for SHG microscopy.
© 2003 Optical Society of America
L. Moreaux, T. Pons, V. Dambrin, M. Blanchard-Desce, and J. Mertz, "Electro-optic response of second-harmonic generation membrane potential sensors," Opt. Lett. 28, 625-627 (2003)