Bisdioxaborine polymethines with large third-order nonlinearities for all-optical signal processing

Organic materials with large third-order nonlinearities in the near-infrared spectral regime are critical in the development of photonic devices to be utilized in all-optical signal processing. We have developed polymethine materials, specifically bisdioxaborine-terminated polymethine dyes, which possess large ultrafast third-order nonlinearities and low nonlinear loss all in the near-infrared spectral regime. An extended bisdioxaborine polymethine anion exhibited the largest value of γ (third-order microscopic nonlinearity) at 1.3 μm (|γ| = 5.7 × 10-32 esu) and showed no characteristics of symmetry breaking, unlike other polymethines of similar lengths. A neat film of this molecule maintained relatively low linear loss in the near-infrared and showed a large third-order macroscopic nonlinearity at 1.3 μm (|χ(3)| = 3.6 × 10-10 esu), with a temporal response of less than 8 ps. Furthermore, the real part of χ(3) was nearly an order-of-magnitude larger than the imaginary component. Consequently, this material exhibited good figures of merit for all-optical signal processing throughout the entire telecommunications band. Copyright © 2006 American Chemical Society.