Abstract

Recently, we reported four novel organic compounds that have shown strong two-photon absorption CTPA) and consequent optical-limiting behavior in THF solutions.¹ Among these four compounds, only one compound, 2,5-benzothiazole 3,4-didecyloxy thiophene (or BBTDOT hereafter), possesses both a large molecular TPA coefficient and very high solubility. For this reason BBTDOT can be further used to dope solid matrices for TPA purposes. In this paper, we present preliminary experimental results on optical-limiting and stabilization behavior exhibited by BBTDOT-doped solid materials. Two transparent materials are chosen as solid matrices: i) optical-grade epoxy and ii) composite glass. The linear one-photon-absorption behavior of BBTDOT in epoxy and composite glass is nearly the same as that in a liquid (THF) solution.¹ As an example, the linear absorption spectrum of a BBTDOT-doped epoxy film is shown in Fig. 1. The tested film is 40 μm thick with a dopant concentration of 5 × 10⁻³ M/L; the molecular structure of the dopant is shown in the top-right corner of Fig. 1. For comparison, the absorption spectrum of an undoped epoxy film with the same thickness is also shown in Fig. 1 by a dashed curve. Figure 1 shows that there is a stronger UV absorption in the spectral range of 300–400 ran due to the dopant. Under illumination of an intense visible-laser radiation both BBTDOT-doped-epoxy and composite-glass samples strongly emit frequency-upconversion fluorescence. This implies a strong two-photon-absorption process taking place in these solid samples.

© 1995 Optical Society of America