This PDF file contains the front matter associated with SPIE Proceedings Volume 6646, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing

Recent research results on DNA-lipid complexes have shown various attractive features on E/O or O/E devices, optical memories, switches and sensors by intercalating optical dye into DNA double helix. Physical properties of DN-lipid complexes are greatly dependent on kinds of lipids and chiral lipids from α-amino acids were prepared so that self-assembled structure of DNA molecules was organized. DNA-L-alanine-derived lipid formed a self-assembled film with a liquid crystalline structure, which showed a less water absorption. DNA devices absorbed water under high humidity which led to decreases of optical functions. However, it was possible to encapsulate the DNA-lipid complexes into sol-gel materials so that a water permeation was prevented by glass to stabilize and to keep the optical functions for a long time.

Resistivity studies were carried out on DNA-based polymer films and selected traditional polymer films, including PMMA and APC. The films were spin coated on glass slides configured for guarded electrode measurements of resistance. The measurements used the alternating polarity method to determine the applied-voltage-dependent current independent of charging and background currents. The data for the temperature dependence of all the polymers were fitted to a common Arrhenius-type expression plus a constant. The poling studies described various dependencies of the measured electro-optic coefficient on how the heating and electric field are applied to the films. The severe impact of poling DNA-based films with vacuum-deposited gold electrodes and the persistent problem of electrode burning and failure presumably due to the high electric fields at the electrode edges are described. How these problems were managed is discussed. The presence of an emf following poling of the DNA-based films is described.

A Polyaniline (PAn)/ DNA complex has been successfully prepared by the photopolymerization of dimeric aniline via photocatalytic reaction of Ru(bpy)₃²⁺ in the presence of DNA. The reaction occurs even in the solution at pH 3.0 - 6.0, due to the specific local "lower-pH" environment provided by DNA. The PAn in the complex has ordered structure associated with double-helical DNA. The complex contains photocatalyst, Ru(bpy)₃²⁺, even after purification and the Ru(bpy)₃²⁺ also works as emitting material. A Ru(bpy)₃²⁺ complex-based red-emitting diode with a fast turn-on response was successfully fabricated by employing this novel, processable and water-soluble PAn/DNA complex.

DNA is a polyelectrolyte capable of forming thin films with interesting optical properties. We investigated refractive indices and optical anisotropy of films of the native, sodium ion-based DNA (Na-DNA) and DNA bearing the cetyltrimethylammonium ion (DNA-CTMA) using a prism coupler technique. The light polarization direction was either parallel (n_TE) or perpendicular to the surface plane of the films (n_TM). The index values and the birefringence of DNA films vary considerably depending on the type of the counter-ion, the film fabrication method and the relative humidity (RH) of the environment. A high negative birefringence in films of Na-DNA, n_TE-n_TM = -0.03 at an RH ~ 55 %, was measured in solution-cast films, indicating that the optically anisotropic DNA molecules are aligned in the plane parallel to the film surface. Refractive indices of DNA-CTMA thin films were smaller and more isotropic than those for films of Na-DNA polymer. The prism coupler reflectance curves showed a hysteresis of the index values when the RH of a DNA-CTMA film environment varied. Polarization microscopy studies showed liquid-crystalline textures at the edges of Na-DNA and DNA-CTMA films.

A DFB laser structure utilizing dye-doped-DNA-lipid films and etchless grating has been studied for potential application to thin-film single longitudinal mode lasers. Although further improvement should be necessary for laser characteristic, the lasing threshold of about 1 mJ/cm² was obtained and single longitudinal mode operation has been successfully achieved.

Because the fluorescence from organic dye is enhanced when it is intercalated or bound to DNA double strands, a lot of studies on optical amplification and lasing have been made. In this study, we investigated the optical and lasing properties of several cyanine dyes incorporated in DNA in solution and complex films. At first, we confirmed that the addition of DNA into dye solutions strongly enhances the fluorescence intensity, and also affects the degree of molecular aggregation. We fabricated the films composed of DNA, dye, and lipid by two methods, and observed the amplified spontaneous emission (ASE) under the excitation of 532 nm laser pulses with sub-mJ energy. We also made a thin film DFB dye laser by forming DNA/dye/lipid films on a grating plate, from which a laser action was observed under optical pumping.

Third-order nonlinear optical properties were investigated for the system incorporating the Disperse Red 1 dye and the deoxyribonucleic acid - cetyltrimethylammonium complex (DNA-CTMA). The interaction of the dye with the DNA chains does not lead to major changes of the nonlinear optical effects due to the DR1 dye. Polarization dependences of the nonlinear absorption in this system reveal, however, some indications that the interactions may lead to ordering of the dye molecules against the DNA chains.

All-optical switching has been theoretically analyzed in LOV2 phototropin, the blue light plant photoreceptor based on nonlinear intensity-induced excited-state absorption. The transmission of a cw probe laser beam at 660 nm through LOV2 protein can be controlled by a cw or pulsed pump laser beam at 442 nm, respectively. This modulation is sensitive to the small-signal absorption coefficient, absorption cross-section of the excited L-state at pump beam wavelength and sample thickness. It is shown that the unique spectral and kinetic properties of wild-type LOV2 and LOV2-C39A mutant, result in the probe beam getting completely switched off (100% modulation), by the pump laser beam of intensity 50 kW/cm² and 1 kW/cm², respectively. The switching response in LOV2-WT is faster (~μs) than in LOV2-C39A mutant (~ms). The results have been used to design an optically-addressed spatial light modulator and all-optical NOT, and the universal NAND and NOR logic gates. The results show the applicability of this novel plant photoreceptor protein for photonic applications.

Nanoscale sensing arrays utilizing the unique properties of the optical protein bacteriorhodopsin and colloidal semiconductor quantum dots are being developed to detect minute concentrations of airborne toxins. This paper describes an innovative method to activate bacteriorhodopsin-based sensors with the optical output of quantum dots, producing a measurable electrical response from the protein. The ability of quantum dots to activate nanoscale regions on bacteriorhodopsin-based electrodes allows sub-micron sensing arrays to be created due to the ability to activate site-specific regions on the array. A novel method to modulate the sensor's electrical output to obtain both "on" and "off" states is also achieved utilizing the fluorescence resonance energy transfer characteristics of a bacteriorhodopsin/quantum dot system. Apart from applying this technology to toxin detection arrays, the ability to readily manipulate the protein's electrical and optical characteristics could have implications in other areas of nanobiotronics.

A new generation of inertial measurement technology is being developed, enabling a 10-micron particle that is "aware" of its geospatial location and responds to this information. The proposed approach combines an inertially-sensitive nano-structure or nano-fluid/structure system with a micro- or nano- sized chemical reactor that functions as an analog computer. Like conventional MEMS IMUs, this device would use a structural or fluid-structures system that deforms in response to inertial forces. However, the device would replace the electronics computational equipment of a conventional MEMS IMU with a chemical reactor that both integrates the sensed accelerations to derive velocity and position and records these measurements. Originally, a cantilever-controlled valve used to control a first order chemical reaction was proposed. The feasibility of this concept was evaluated with the result of a device with significant size reductions with a comparable gain but lower bandwidth comparable to current accelerometers. New concepts with additional refinements have been investigated. Buoyancy-driven convection coupled with a chemical recording technique is explored as a possible alternative. Using a micro-track containing regions of different temperatures or concentrations of specific chemical units, a range of accelerations can be recorded and the position determined. The result is a device that offers improvement over the original concept.

DNA-based materials offer new possibilities for holographic information inscription for photonic applications, in particular because of a very short operational time. Recent results for dynamic holographic recording/erasure of gratings in DR1:DNA-CTMA thin films are presented. We discuss the possibilities and perspectives of numerical modelling of underlying fast "microscopic" physical processes, in a framework of a kinetic Monte Carlo simulation method developed recently for studies of various aspects of inscription/erasure of gratings in azopolymers with doped and functionalized dyes.

This paper reports on the use of new DNA-based biopolymers as the semiconducting layer in field effect transistors. Thin-film field effect transistor (FET) structures are fabricated with two different DNA-biopolymers as semiconductor layers, and two different field effect transistor structures are studied. Current voltage characteristics of the FETs show that the devices are operating in depletion mode.

Surface enhanced resonant Raman scattering (SERRS) signals are enhanced by confining the scattering to the core of a hollow core microstructured optical fiber. An analyte solution of rhodamine 6G adsorbed on colloidal silver was used. This solution filled both the core and cladding of the fiber. It was found that SERRS signals could be collected from the solution in the fiber beyond the detection limit of an equivalent free space system.