Impressive nonlinear optical responses of a cationic porphyrin derivative in a flexible all-polymer Bragg stack on optical Tamm mode coupling

Abstract

Herein, we experimentally demonstrate the enhanced nonlinear optical (NLO) response of 5,15-di(pentafluorophenyl)-10,20-bis(4-N-methylpyridyl)Zn(II) porphyrin, abbreviated as ZnP+, by utilizing Tamm plasmon polaritons formed at the interface between a truncated all-polymeric Bragg reflector and a thin gold film. In order to do so, the dielectric layer adjacent to the Au film is doped with ZnP+ molecules. The nonlinear optical absorption (NLA) and optical limiting properties are investigated by means of a single beam Z-scan method using a Q-switched Nd:YAG laser delivering 7 ns pulses at a wavelength of 532 nm. Compared to the reference sample of a single layer ZnP+ film, the enhancement factor of optical nonlinearity with the Tamm structure was found to be ∼6-fold. Optical limiting efficiency is also found to be greatly improved with a limiting threshold of 1.04 J cm⁻². The better response is due to the enormous optical field intensity confined near the metal–dielectric interface that facilitates greater light–matter interactions and thus NLO activities in ZnP+ molecules at low input energies. These findings elucidate the efficiency of Tamm plasmon-polaritons in the optical switching and limiting applications. We believe that due to the involvement of a solution processed Bragg reflector made up of polymeric materials, our Tamm structure has greater practical value in realizing flexible, cost-effective, low threshold input all-optical devices that are susceptible to photonic integration.