School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Science. 2010 Mar 19;327(5972):1485-8. doi: 10.1126/science.1185117. Epub 2010 Feb 18.
All-optical switching applications require materials with large third-order nonlinearities and low nonlinear optical losses. We present a design approach that involves enhancing the real part of the third-order polarizability (gamma) of cyanine-like molecules through incorporation of polarizable chalcogen atoms into terminal groups, while controlling the molecular length to obtain favorable one- and two-photon absorption resonances that lead to suitably low optical loss and appreciable dispersion enhancement of the real part of gamma. We implemented this strategy in a soluble bis(selenopyrylium) heptamethine dye that exhibits a real part of gamma that is exceptionally large throughout the wavelength range used for telecommunications, and an imaginary part of gamma, a measure of nonlinear loss, that is smaller by two orders of magnitude. This combination is critical in enabling low-power, high-contrast optical switching.
全光开关应用需要具有大三阶非线性和低非线性光学损耗的材料。我们提出了一种设计方法，通过将可极化的硫属原子掺入末端基团来增强类似菁的分子的三阶极化率（γ）的实部，同时控制分子长度以获得有利的单光子和双光子吸收共振，从而导致适当低的光损耗和 γ 的实部可观的色散增强。我们在一种可溶性双（硒吡喃基）庚甲川染料中实现了这一策略，该染料在整个用于电信的波长范围内表现出异常大的γ实部，以及γ的虚部，这是衡量非线性损耗的一个指标，小两个数量级。这种组合对于实现低功率、高对比度的光开关至关重要。
