Third-order nonlinear optical properties of phycobiliproteins from cyanobacteria and red algae

Abstract

Second hyperpolarizability (γ) measurements as well as third harmonic generation (THG) imaging was performed to determine if phycobiliproteins contribute to cyanobacteria THG, and to establish if phycobiliproteins are suitable dyes for THG microscopy. Three phycobiliproteins and one phycobilin were investigated via THG ratio γ measurements, revealing phycocyanobilin has ~7× higher γ than β-carotene, a standard THG dye. Phycobiliproteins also had large γ values, showing they are promising THG dyes. Stoichiometric summations of phycobilin γ values revealed they are the dominant source of THG signal from phycobiliproteins. THG imaging was performed to demonstrate phycobiliproteins and phycobilins can be useful THG dyes.