Daniel L. Rode

Precision fabrication of D-shaped single-mode optical fibers by in situ monitoring

A technique has been developed to locally remove, over a distance of several millimeters of fiber length, the cladding layer of single-mode (at the 1300 nm wavelength) optical fibers with 1 /spl mu/m depth precision by use of mechanical lapping and in situ optical transmission monitoring. A cylinder lap dressed with diamond is used to perform high-pressure mechanical lapping. The in situ monitoring technique is based on the specific different attenuations exhibited by higher order propagating modes (for 633 nm light) as the cylinder penetrates into the fiber. Advantages include relatively rapid overall processing, high lapping rate, good optical surface quality, and 1 /spl mu/m precision. Experimental results are presented and analyzed by an approximate geometrical-optics model. >

Optical control of focal epilepsy in vivo with caged γ-aminobutyric acid

There is enormous clinical potential in exploiting the spatial and temporal resolution of optical techniques to modulate pathophysiological neuronal activity, especially intractable focal epilepsy. We have recently utilized a new ruthenium‐based caged compound, ruthenium‐bipyridine‐triphenylphosphine–γ‐aminobutyric acid (RuBi‐GABA), which releases GABA when exposed to blue light, to rapidly terminate paroxysmal activity in vitro and in vivo.

Optical suppression of experimental seizures in rat brain slices

Purpose:  To determine if a small ultraviolet emitting diode (UV LED) could release sufficient γ‐aminobutyric acid (GABA) from a caged precursor to suppress paroxysmal activity in rat brain slices.

Low-loss, single-mode, organic polymer waveguides utilizing refractive index tailoring

Low-loss, single-mode optical waveguides have been fabricated from photopolymerizable acrylic monomers. The material system consists of a low-index cladding resin and a high-index core resin. The two resins are miscible so that precise control over the refractive index can be obtained. This allows the fabrication of single-mode waveguides with specific cross-sectional dimensions. One advantage of this is the ability to fabricate waveguides with high coupling efficiencies to other devices such as optical fiber or semiconductor lasers. The materials adhere to a wide variety of substrates and exhibit average waveguide losses of 0.56 dB/cm at 1300 nm for single-mode waveguides. Details of the fabrication procedure, index of refraction tailoring technique, and waveguide loss data are presented.

Efficient multimode optical fiber-to-waveguide coupling for passive alignment applications in multichip modules

An efficient optical fiber-to-waveguide coupling technique is described, using a novel transcision cut, alignment ways, and D-shaped fibers. Fiber-to-waveguide coupling efficiencies as high as 96% have been achieved with multimode graded-index fibers and ridge polymer optical waveguides. Advantages of using this new coupling technique include ease of fiber-to-waveguide alignment interior to the substrate edge, passive coupling, and high coupling efficiency. >

Far-field radiation and modal dispersion of 1310 nm dispersion-optimized fiber at 850 nm

Far-field radiation pattern measurements have been used to evaluate the modal structure and dispersion associated with 0.85- mu m wavelength light launched from high-brightness light-emitting diodes into TIA class-IVa fiber. The measured far-field radiation pattern of the light intensity emitted from the end of the optical fiber is compared to the far-field radiation pattern calculated from the Fraunhofer approximation to the diffraction integral with the result that two linearly polarized modes propagate in the optical fiber and the optical power is nearly equally distributed between the two modes. The modal dispersion associated with the use of a 0.85- mu m wavelength emitter and a TIA class-IVa fiber is evaluated to be 2.3 ns/km, which is adequate for a variety of local-area networks and point-to-point optical communication links. >

Efficient optical fiber-to-waveguide coupling suitable for passive alignment

A technique has been developed for coupling multimode fiber to ridge waveguides on a substrate. It consists of D-fiber and polymer waveguides. Fabrication techniques for each are presented. Average insertion losses as low as 1.5 dB for coupling multimode optical fiber to 6.0-cm-long waveguides were measured. It is noted that this new coupling technique has great potential for passive alignment of optical fiber to ridge waveguides.<<ETX>>