  All-optical switches are introduced which are based on deoxyribonucleic acid
(DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a
push-pull, luminescent nonlinear pyrazoline derivative. Optical birefringence
is found in the organic nanofibers, with fully reversible switching controlled
through continuous-wave laser irradiation. The photoinduced signal is
remarkably large, with birefringence highlighted by optically-driven refractive
index anisotropy approaching 0.001. Sub-millisecond characteristic switching
times are found. Integrating dye-intercalated DNA complex systems in organic
nanofibers, as convenient and efficient approach to template molecular
organization and controlling it by external stimuli, might open new routes for
realizing optical logic gates, reconfigurable photonic networks and sensors
through physically-transient biopolymer components.
