Abstract

Nonlinear organic materials attract much attention because of their large optical nonlinearities and femtosecond response. Yamashita and coworkers measured, a nonlinear refractive index n₂ of 4-(N,N- dimethylamino)-3-acetamidonitrobenzene (DAN)¹ which is one of the best quadratic nonlinear organic materials. Its n₂ value is very large (1.7 × 10⁴ times larger than that of a glass fiber), and they compressed the optical pulses from 39 to 22 fs without amplification using a single-mode DAN crystal cored fiber. The DAN fiber also has relatively large group velocity dispersion and higher-order dispersion which dominate nonlinear femtosecond pulse propagation as well as n₂. In the present study, we investigate the input pulse power dependence of the fiber output spectra in the femtosecond time region in order to understand the ultrafast nonlinear propagation mechanism in the DAN fiber.

© 1993 Optical Society of America