This communication focuses on the integration of organic nonlinear optical and gain materials into plasmonic and
metamaterial device architectures and most specifically focuses on the integration of organic electro-optic (OEO)
materials into such structures. The central focus is on structures that lead to sub-optical wavelength concentration of
light (mode confinement) and the interaction of photonic and plasmonic modes. Optical loss and bandwidth limitations
are serious issues with such structures and optical loss is evaluated for prototype device architectures associated with the
use of silver and gold nanoparticles and membranes supporting plasmonic resonances. Electro-optic activity in organic
materials requires that chromophores exhibit finite noncentrosymmetric organization. Because of material conductivity
and integration issues, plasmonic and metamaterial device architectures are more challenging than conventional triple
stack all-organic device architectures and electro-optic of a given OEO material may be an order of magnitude less in
such structures. Because of this, we have turned to a variety of materials processing options for such integration
including crystal growth, sequential synthesis/self assembly, and electric field poling of materials deposited from
solution or by vapor deposition. Recent demonstration of integration of silicon photonic modulator and lithium niobate
modulator structures with metallic plasmonic structures represent a severe challenge for organic electro-optic material
plasmonic devices as these devices afford high bandwidth operation and attractive V<sub>μ</sub>L performance. Optical loss
remains a challenge for all structures.
Hypericin is a novel, highly fluorescent photosensitizer that exhibits selective tumor cell uptake properties and is particularly resistant to photobleaching. In this study, we have characterized hypericin uptake in human pancreatic tumor cells with relation to incubation time, cell number, and drug concentration. <i>Ex vivo</i> hypericin based fluorescence spectroscopy was performed to detect the presence of MIA PaCa-2 pancreatic tumor cells in the peritoneal cavity of BALB/c nude mice, as well as to quantify gross tumor burden. Hypericin based cytology of peritoneal lavage samples, using both one and two photon laser confocal microscopy, demonstrated more than a two-fold increase in fluorescence emission of pancreatic tumor cells as compared to control samples. <i>In vitro</i> treatment of pancreatic cancer cells with hypericin based photodynamic therapy showed tumor cell cytotoxicity in a drug dose, incident laser power, and time dependent manner. For these experiments, a continuous wavelength solid-state laser source (532 nm) was operated at power levels in the range of 100-400 mW. Potential applications of hypericin in tumor diagnosis, staging, and therapy will be presented.
We present recent developments in etchless fabrication techniques for defining low-loss waveguides in polymers. Photobleached waveguides with optical propagation loss equal to the inherent loss of the core materials have been fabricated, as well as Mach-Zehnder modulators with 4.5 volt driving voltage and fiber-to-fiber insertion loss of 8 dB. In terms of new configurations, a novel linearized directional coupler modulator that has a 10 dB enhancement in the dynamic range compared to conventional Mach-Zehnder modulators is presented. We report on the design and fabrication of polymer digital optical switches with switching voltages of 7 volts and extinction ratios greater than 20 dB. Simultaneous serrodyne frequency shifting and high-frequency phase modulation in a polymer phase modulator are demonstrated in order to simplify the setup required to implement two-color heterodyne ranging. Finally, we propose implementations of optical signal processors based on polymer optical delay lines, couplers, and electrooptic modulators, and discuss their applications to optical signal processing.