Multiphoton-absorbing organic materials for microfabrication, emerging optical applications and non-destructive three-dimensional imaging

TLDR

Two‑photon absorption (TPA) is a non‑resonant process where two photons are simultaneously absorbed via a virtual state, producing a quadratic dependence of absorption on light intensity and highly localized photoexcitation. The paper reviews recent advances in designing and synthesizing efficient, stable, multifunctional TPA organic materials for use in microfabrication and functional microstructure fabrication. Microfabrication is achieved through two‑photon induced free‑radical polymerization of acrylate monomers and cationic polymerization of epoxide monomers using commercial and custom high‑TPA photoinitiators, while two‑photon facilitated photoisomerization of a fulgide enables photochromism and interferometric image recording. Three‑dimensional two‑photon fluorescence imaging of a polymer‑coated substrate achieved markedly higher signal‑to‑noise ratios and resolution than conventional single‑photon laser‑scanning confocal microscopy. © 2000 John Wiley & Sons,.

Abstract

Non-resonant two-photon absorption (TPA) can be defined as the simultaneous absorption of two photons, via a virtual state, in a medium. TPA exhibits a quadratic dependence of absorption on the incident light intensity, resulting in highly localized photoexcitation. Recent developments in the design and synthesis of efficient, stable TPA organic materials are discussed. Microfabrication via two-photon induced free radical polymerization of acrylate monomers and cationic polymerization of epoxide monomers was accomplished using commercially available photoinitiators, and also a custom-made compound possessing high two-photon absorptivity. Two-photon facilitated photoisomerization of a fulgide in solution and in a polymer thin film demonstrated two-photon induced photochromism and its application in interferometric image recording, respectively. Greatly enhanced signal-to-noise ratios and resolution were achieved in the non-destructive three-dimensional two-photon fluorescence imaging of a polymer-coated substrate versus conventional single-photon laser scanning confocal microscopic imaging. Multifunctional TPA organic materials and fabrication of functional microstructures are also discussed. Copyright © 2000 John Wiley & Sons, Ltd.