Two-photon absorption (TPA) spectra of three organic compounds have been directly measured by an approach of using tunable laser from an optical parameter amplifier as an excitation source. The output intensity of the optical parameter amplifier can cover a broad spectral range 400-2000 nm, and the same intensity in the whole spectral range can be easily adjusted. Therefore, the measurement based on this method is direct and reliable. The experimental results show that the profiles of the TPA spectra are quite similar to those of the linear absorption spectra. All of these compounds exhibit large TPA cross-section in a broad spectral range from 750 to 1100 nm.
Chemical Physics Letters,
Vol. 352, no. 3-4 (Jan 2002), pp. 240-244