Allen, Taylor G. ; Perry, Joseph W. Marder, Seth R. Chemistry and Biochemistry Dickson, Robert Reynolds, John R. Silva, Carlos Adibi, Ali ; Perry, Joseph W.
In this dissertation, three studies were presented that involve the spectroscopic characterization of either nonlinear optical or biophotonic materials. The first study (Chapter 3) proposed judicious bulky substitution of cyanine-like, polymethine dyes with large intensity dependent refractive indices to effectively mitigate aggregation between dyes in thin film polymer blends of interest for all-optical signal processing applications in the near infrared (NIR). Linear characterization and Z-scan measurements of these blends at 1550 nm confirmed that bulky groups suppress aggregation in the solid state, thus lowering two-photon absorption (2PA) and improving the nonlinear optical performance of these films. The second study (Chapter 4) proposed a series of planar, fused-ring, organic, quadrupolar chromophores of type A-π-D-π-A with the potential to demonstrate large 2PA cross-sections for optical limiting applications in the NIR. Nondegenerate 2PA measurements revealed that these compounds have large 2PA cross sections and spectral coverage in the NIR, which can be controlled synthetically via structural changes in the core and acceptor groups at the molecule’s periphery. The third study (Chapters 5-6) proposed high refractive index replicas of photonic crystal-like hole patterns harvested from Coscinodiscus wailessii diatom frustules as sustainably-producable, biophotonic elements for lensless light focusing of NIR radiation at the micro-scale. Linear spectrophotometric and imaging measurements confirmed that these replicas concentrate NIR light via diffraction, which can be manipulated with changes in the index of the frustule through solid-gas conversion chemistries with excellent shape preservation.
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Spectroscopic characterization of nonlinear optical and biophotonic materials