Nonlinear Optics in Single Crystal Microstructures of Organic Materials

9634268 Thakur这个项目的一个主要目标是使用特定有机单晶薄膜的大非共振非线性折射率来演示皮秒全光学逻辑和光学双稳态。总体项目目标包括：i）制备有机二阶和三阶光学材料的单晶薄膜和器件微结构，ii）详细研究薄膜的非共振非线性，iii）演示器件，包括波导中的相位匹配SHG，全光和电光开关和逻辑。非线性光学研究将包括二阶光学薄膜中的偏振相关倍频和电光效应以及三阶光学薄膜的时间和波长分辨非线性折射率测量。在非共振三阶过程中所涉及的机制将被阐明，皮秒全光逻辑将使用特定的有机材料和器件的几何形状。利用非常大的二阶非线性的有机薄膜，电光开关和逻辑将被证明。已知诸如聚二乙炔的特定共轭聚合物具有极大的非线性折射率沿着，同时在非共振域中具有低吸收系数。 只有当聚合物链被组织成单晶时，才能获得如此大的非线性。特定的有机分子晶体（例如NPP、DAST）具有非常大且稳定的二阶非线性，如果可以制备单晶膜和波导，则其可以用于许多应用（例如用于红外二极管激光器的SHG、电光开关）。主要研究者建立的方法（“剪切法”及其修改版本）将用于制备有机二阶和三阶光学材料的单晶膜。随后，将使用该薄膜制造法布里-珀罗标准具和波导几何结构中的特定器件微结构。薄膜和波导中的非线性光学测量将使用已建立的程序进行。最近，我们已经证明了全光开关使用的非共振非线性的聚二乙炔薄膜，放置在法布里-珀罗腔。所测量的开关时间受到所使用的脉冲宽度（30 ps）的限制。 详细的测量涉及全光逻辑和双稳态将在这项拟议的工作中使用！ 皮秒和亚皮秒脉冲。超快全光开关和逻辑在一个紧凑的设备的几何形状应该有各种未来的应用在光子学。具有非常大的二阶非线性的有机材料的单晶膜和波导被期望在频率转换和电光学中具有近期的应用。这些研究对于深入理解这些非共振非线性光学效应和实现许多实际应用具有重要意义。 ***

9634268 Thakur A major objective of this project is to demonstrate picosecond all-optical logic and optical bistability using the large off-resonant nonlinear refractive indices of specific organic single crystal films. The overall project objectives include: i) preparation of single crystal films and device microstructures of organic second and third order optical materials, ii) detailed studies of the off-resonant nonlinearities of the films and, iii) demonstration of devices including phase-matched SHG in waveguides, all-optical and electro-optic switching and logic. The nonlinear optical studies will include polarization dependent SHG and electro-optic effects in second order optical films and time and wavelength resolved nonlinear refractive index measurements for the third order optical films. The mechanisms involved in the off-resonant third order processes will be elucidated and picosecond all-optical logic will be demonstrated using specific organic materials and device geometries. Utilizing organic films of very large second order nonlinearities, electro-optic switching and logic will be demonstrated. Specific conjugated polymers such as polydiacetylenes are known to have extremely large nonlinear refractive indices along with low absorption coefficients in the off-resonant domain. Such large nonlinearities are obtained only if the polymer chains are organized as a single crystal. Specific organic molecular crystals (e.g. NPP, DAST have very large and stable second order nonlinearities which can be utilized in many applications (e.g. SHG for infrared diode lasers, electrooptic switching), if single crystal films and waveguides can be prepared. A method ("shear method" and its modified version) that the principal investigator has established, will be utilized for the preparation of single crystal films of the organic second and third order optical materials. Subsequently specific device microstructures in the Fabry-Perot etalon and waveguide geom etries will be fabricated using the films. The nonlinear optical measurements in the films and waveguides will be performed using established procedures. Recently, we have demonstrated all-optical switching using the off- resonant nonlinearity of a polydiacetylene film, placed in a Fabry-Perot cavity. The measured switching time was limited by the pulse-width (30ps) that was used. Detailed measurements involving all-optical logic and bistability will be performed in this proposed work using ! picosecond and sub-picosecond pulses. Ultrafast all-optical switching and logic in a compact device geometry should have a variety of future applications in photonics. Single crystal films and waveguides of organic materials having very large second order nonlinearities are expected to have near-term applications in frequency conversion and electro-optics. The research as proposed is important for fundamental understanding of these off-resonant nonlinear optical effects and for realizing many practical applications. ***