Two-photon absorption based optical limiting and stabilization in organic molecule-doped solid materials

Optical limiting and stabilization via two-photon absorption (TPA) in organic molecule-doped solid materials have been investigated. The nonlinear materials are epoxy rod and a composite glass rod doped with the same organic dopant (2,5-benzothiazole 3,4-didecyloxy thiophene). An ultrashort laser source with 0.5 ps pulsewidth and 602 nm wavelength was employed. The transmissivity of these two materials has been measured as a function of the input beam intensity. The measured results can be well fitted based on the assumption that TPA is the predominant mechanism producing the observed optical limiting behavior. Also, optical stabilization behavior is observed, and, at ∼930 MW/cm² input intensity level, the output intensity fluctuation is three times less than the input intensity fluctuation.