Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

The present invention is directed toward an interferometric sensor that permits the simultaneous measurement of a change in more than one environmental condition. The interferometric sensor comprises an optical fiber and a plurality of sensing regions positioned in an operable relationship to the optical fiber. Each sensing region has partially reflective boundaries and produces an interferometric signal.

Interferometric sensors utilizing bulk sensing mediums extrinsic to the input/output optical fiber

An optical sensor and a method of manufacturing such as sensor are provided. The sensor includes a lead optical fiber with a single piece optical element joined permanently joined to its forward end. The optical element defines a spacer with a cavity therein at one end, and a diaphragm at the opposite end. The diaphragm is flexible in response to a parameter and the sensor defines a sensing Fabry-Perot resonator.

Single piece fabry-perot optical sensor and method of manufacturing the same

A diaphragm optic sensor comprises a ferrule including a bore having an optical fiber disposed therein and a diaphragm attached to the ferrule, the diaphragm being spaced apart from the ferrule to form a Fabry-Perot cavity. The cavity is formed by creating a pit in the ferrule or in the diaphragm. The components of the sensor are preferably welded together, preferably by laser welding. In some embodiments, the entire ferrule is bonded to the fiber along the entire length of the fiber within the ferrule; in other embodiments, only a portion of the ferrule is welded to the fiber. A partial vacuum is preferably formed in the pit. A small piece of optical fiber with a coefficient of thermal expansion chosen to compensate for mismatches between the main fiber and ferrule may be spliced to the end of the fiber.

Optical fiber sensors for harsh environments

A Fabry-Perot optical sensor for sensing a parameter such as pressure or the like is provided. The sensor includes a lead optical fiber from the end of which projects a spacer having an end surface curving inwardly. A diaphragm extends across the forward end of the spacer. The diaphragm is flexible in response to the parameter to be measured and defines a forward reflector of the Fabry-Perot cavity within the optical sensor. A method for manufacturing such a sensor is also provided.

Fabry-perot optical sensor and method of manufacturing the same

An optical interferometer comprises a multi-mode sapphire fiber as a high temperature sensor. One end of the sapphire fiber is coupled to a silica fiber and, in turn, to the sapphire fiber. The sapphire fiber sensor produces reference and sensor reflections that produce optical fringes at the output of a detector coupled to the silica optical fiber via an opto-coupler. The optical fringes are related to displacements of the sensor which, in turn, can provide an indirect measurement of pressure, strain or temperature of the surface.

Sapphire optical fiber interferometer

This dissertation demonstrates the feasibility of using novel electrostatic self-assembly (ESA) methods to fabricate linear and nonlinear optical thin films and components. The ESA process involves the layer-by-layer alternate adsorption of anionic and cationic complexes from aqueous solutions. Selection of the molecules in each layer, their orientation at the molecular level, and the order in which the layers are assembled determine the film’s bulk optical, electronic, magnetic, thermal, mechanical and other properties. In this work, the capability of nanoscale control over film optical properties allowed the fabrication of complicated refractive index profiles required for linear optical interference filters. The inherent ordered nature of ESA films yielded extremely stable noncentrosymmetric thin films for second-order nonlinear optical applications. The ESA technique offers numerous advantages over conventional thin film fabrication methods and offers great potential in commercial applications such as reflectance and AR filters, EO waveguides and modulators and other optoelectronic devices. The structure of each monolayer in ESA films is dependent on the processing parameters, producing subsequent variations in bulk film properties both intentionally and incidentally. As this method is still in its infancy, variations in ESA processing methods, including process automation, are considered first in this document. These results allowed carefully controlled refractive index experiments and the synthesis of both step and graded index structures, several microns thick. Dielectric stack, Rugate, and antireflection optical interference filters were designed, synthesized and demonstrated. χ films of both commercially available polymer dyes and novel polymers designed specifically for the ESA process were demonstrated using second harmonic generation. UV/vis spectroscopy, ellipsometry and atomic force microscopy analysis are presented. for my father, Michael John Lenahan, who has worked hard all his life to give me mine.

Electrostatic Self-Assembly of Linear and Nonlinear Optical Thin Films

This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated.

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Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

This report summarizes technical progress on the program Multiplexed Optical Fiber Sensors for Coal Fired Advanced Fossil Energy Systems funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed jointly by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering and the Department of Materials Science and Engineering at Virginia Tech. This three-year project started on October 1, 2008. In the project, a fiber optical sensing system based on intrinsic Fabry-Perot Interferometer (IFPI) was developed for strain and temperature measurements for Ultra Supercritical boiler condition assessment. Investigations were focused on sensor design, fabrication, attachment techniques and novel materials for high temperature and strain measurements. At the start of the project, the technical requirements for the sensing technology were determined together with our industrial partner Alstom Power. As is demonstrated in Chapter 4, all the technical requirements are successfully met. The success of the technology extended beyond laboratory test; its capability was further validated through the field test at DOE NETL, in which the sensors yielded distributed temperature mapping of a testing coupon installed in the turbine test rig. The measurement results agreed well with prior results generated with thermocouples. Inmore » this project, significant improvements were made to the IFPI sensor technology by splicing condition optimization, transmission loss reduction, sensor signal demodulation and sensor system design.« less

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Anbo Wang

Papers

Sapphire optical fiber interferometer

Electrostatic Self-Assembly of Linear and Nonlinear Optical Thin Films

Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

Multiplexed Optical Fiber Sensors for Coal Fired Advanced Fossil Energy Systems

Invited) Gold Nanobridge Enhanced Fiber Optic Sensor