Brian K. Canfield

Fabrication and characterization of single-mode electro-optic polymer optical fiber

We report on what we believe is the first demonstration of single-mode polymer optical fiber with embedded electrodes. We show that the electrodes can be used to pole the dye-doped core and to electro-optically phase modulate the light in the waveguide.

High-efficiency optical phase conjugation by degenerate four-wave mixing in volume media of disperse red 1-doped poly(methyl methacrylate)

High-efficiency optical phase conjugation (PC) by degenerate four-wave mixing in stress-processed volume media of disperse red 1 (DR1)-doped poly(methyl methacrylate) in the transparent region (647 nm) is reported. With vertically polarized counterpropagating pump waves, PC reflectivities of 43% and 37% were achieved, respectively, for a horizontally and vertically polarized probe wave, which is 50 times higher than the value reported on resonance. Reflectivities over 30% were achieved over a wide range of intensity for both polarization configurations. Photoinduced reorientation of the DR1 chromophore through trans-cis-trans isomerization is the dominant mechanism for the PC wave generation. Other mechanisms involved in the configuration of all vertical polarization waves are also examined. The roles of the polymer matrix and azo-dye photoisomerization in this high-efficiency PC process are also discussed.

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.

Use of quadratic electroabsorption for measurement of the hyperpolarizability β of asymmetric molecules

We show that quadratic electroabsorption (QEA) can be used for measurement of the hyperpolarizability β in asymmetric, polar molecules. QEA has already been used to obtain the second hyperpolarizability gamma in centrosymmetric molecules. However, because of the existence of a static dipole moment µ in asymmetric molecules, β can contribute significantly to the third-order susceptibility measured with the QEA experiment owing to a reorientational mechanism through the mixed term βµ. We apply inhomogeneously broadened, quantum sum-over-states models for both β and gamma to describe the QEA response of asymmetric molecules. Comparing the models and the data for two asymmetric nonlinear optical chromophores, we found that β yields the dominant response. QEA is thus a useful tool for measuring the dispersion of β and can be used for reliable determination of the off-resonant value β_0.

Refractive index profiles of polymer optical fiber preforms

We report a method for determining the refractive index profile of polymer optical fiber preforms by direct beam deflection measurements. The method is simple to use, compact, and has good resolution. The profile is obtained from the deflection data by numerically integrating the differential ray equation for a radial refractive index gradient. Refractive index profiles of both graded-index (GRIN) and step-index fiber preforms are reported.

Optical phase conjugation by non-resonant degeneration four-wave mixing in volume media of DR1-doped PMMA

Optical phase conjugation (PC) by non-resonant degenerate four-wave mixing (DFWM) in thick media of poly(methyl methacrylate) (PMMA) with doped disperse red 1 (DR1) is reported. With vertically polarized counterpropagating pump waves, PC reflectivities of 43% and 37% were achieved respectively for a horizontally and vertically polarized probe wave, which is more than 50 times higher than the value reported on resonance. Reflectivities over 30% were achieved over a wide range of intensity for both polarization configurations. Photoinduced modulation of ordering of the DR1 chromophore is the main mechanism of the PC wave generation. Other mechanisms involved in the configuration of all vertical polarization waves are also examined. Influence of the squeezing process in making volume samples on the PC wave efficiency is significant.

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.

Polymer fibers as optical device components

Single mode polymer optical fibers are promising candidates for all-optical devices because of fabrication flexibility, ability to tailor materials to meet a given application, and ease of fiber fabrication. In this paper, we discuss the fabrication process that is used to make single-mode polymer fibers and more complex fiber structures such as dual-core fibers. We also report on linear characterization studies of these fibers. In particular, we discuss refractive index profile measurements in both graded index and step index fiber preforms, dye concentration profiles, and waveguiding studies in dual-core optical fibers. Such linear-optical characterization is an essential input into the design of all-optical devices.