National Institute of Advanced Industrial Science and Technology (AIST)

Photonics Research

Research areas

1. Structure–property relationship underlying two-photon absorption in π-conjugated molecules.
2. Multiphoton absorbing materials, nonlinear refractive index-changing materials.
3. Measurement technologies for nonlinear optical properties.

Two-photon absorption (2PA) is a phenomenon in which two photons are simultaneously absorbed by a molecule. This process has been used for 3D-resolved fluorescence imaging of living tissues and now is expected to be a key process for use in terabyte-class large-capacity optical memory storage devices. However, high-sensitivity 2PA materials are required for applications that use low intensity laser pulses, because 2PA only occurs in the presence of intense optical fields. We focus our activities on clarifying the structure–property relationship, i.e. what types of molecular structures give excellent 2PA sensitivity. We employ 2PA spectral measurements using femtosecond laser pulses and theoretical calculations of the electronic states based on first principles. In addition, we develop and characterize novel multiphoton absorption materials and nonlinear refractive index-changing materials in worldwide collaborations. Methodologies for reliable and reproducible measurements of nonlinear optical properties are important goals. These activities are applied toward the creation of novel organic materials with high functionalities for photonics applications. We also establish basic theoretical frameworks for the developments.