David J. Welker

CHARACTERIZATION OF SINGLE-MODE POLYMER OPTICAL FIBER AND ELECTROOPTIC FIBER DEVICES

Abstract Polymer optical fiber can be used to make a wide variety of devices such as transmission systems, optical sensors, optical switches/logic, and optical actuators. In this paper, we give a brief overview of devices that are made in fiber and discuss the first demonstration of single-mode polymer optical fiber with embedded electrodes. Future technologies that are made possible with optics are also discussed.

Nonlinear characterization of polymer electro-optic fiber

The second-order nonlinear properties of step-index polymer electrooptic (EO) fiber are discussed. The fiber is fabricated in the Nonlinear Optics Laboratory at WSU. Use of a Mach-Zehnder interferometer to determine the linear electrooptic coefficient of the EO fiber and quadratic electrooptic coefficient for a thin film is discussed. The data thus obtained is shown to be reproducible and of correct magnitude.

Single-mode electro-optic polymer optical fiber

We have made single mode polymer optical fiber with embedded electrodes. The electrodes can be used to pole the dye-doped core and electro-optic phase modulation of light in the waveguide has been demonstrated. The method of lead attachment to the electrodes is discussed and the optical/electrical properties of device structures characterized.

Ultrafast multistability in miniature photomechanical vibration suppressors

It is well known that light has the ability to carry large amounts of information by virtue of its high intrinsic bandwidth and transmission speed. We report on a new class of mechanical fiber devices that are powered by light. In particular, we show that a sensor, logic unit, and actuator function can be built into a mesoscopic polymer optical fiber: The stress sensor converts stress to light, the logic element manipulates the light according to a preprogrammed response, and the actuator provides mechanical displacement. A device that combines all three of these devices into a single monolithic unit can be designed to perform many different smart mechanical and optical logic functions. Furthermore, because optical devices use no electronic components, they allow for highly interconnected architectures of multiple units that result in ultrasmart operation. Such associations of devices, when embedded in a host material, would form an ultrasmart material. We report on the multistable operation of a highly miniaturized vibration stabilizer in a polymer fiber and show that it has an ultrafast photomechanical response. The theory behind the response is also discussed.

Smart mesoscopic photomechanical positioner/actuator, sensor, and all-optical logic unit

Light can interact with a material and change the physical dimensions of the material through several mechanisms: photothermal, electrostriction, molecular reorientation, electronic cloud deformation and Cis-Trans isomerization. In the photothermal mechanism light, upon entering a material, is partially absorbed causing a temperature increase and through thermal expansion an increase in size. Electrostriction causes a net force in the material toward regions of higher light intensity which in a pliable material can result in a dimensional change. Molecular reorientation causes anisotropic molecules in a material to experience an alignment force which can lead to a dimensional change. Electronic cloud deformation can result in a dimensional change due to change in nucleon positions due to changes in the materials electronic structure that results from the lights electric field in the material. Molecules that can undergo a Cis-Trans isomerization in the presence of light have the potential to change the shape of any object because of the forces applied to the material. In this paper we will discuss one method by which the photothermal photomechanical effect can be utilized for device fabrication. The basic device, which we call a Mesoscopic Photomechanical Unit (MPU), can be utilized as a positioner/actuator, sensor, and all-optical logic unit.