Robert M. Hawk

Low Loss Splicing And Connection Of Optical Waveguide Cables

The individual loss mechanisms contributing to the insertion loss of an optical waveguide joint are described and quantified. Losses attributable to the characteristics of individual waveguides as well as losses due to coupling technique are included. The identification and understanding of these loss mechanisms has led to the design of optical waveguide alignment and retention techniques that minimize or avoid these effects. To make a connector useful in field applications of optical cables utilizing these techniques, the hardware must be reliable, stable, low cost, quick, and fully intermateable, as well as providing low insertion loss. Experimental results are given that indicate extrinsic insertion loss as low as 0.3 dB is routinely attainable in each channel of multifiber connections utilizing low-loss optical waveguides.

Polarization Retaining Single-Mode Fiber With Improved Coil Performance

High birefringence, polarization retaining single-mode optical waveguides have been developed for applications requiring stable performance when the fiber is coiled. Recent designs employing high-expansion aluminum-doped stress rods have demonstrated polarization holding parameters better than 6.0 x 10-6m-1 with little degradation of h-parameter or attenuation down to 2 cm diameter coil configurations.

Limited phase-space attenuation measurements of low-loss optical waveguides

Attenuation and near-and far-field measurements, which were made with different launch spot sizes and numerical apertures on sub-1.0-dB/km optical waveguides, have shown that an equilibrium mode distribution is not established in the 1.1-km length. It was experimentally found that the source launch conditions could be described by an effective mode volume (EMV) that was found to be correlated with the measured attenuation rate. By using an EMV transfer model, the insertion loss of a 3.3-km concatenated section was predicted within 0.21 dB of that measured for a variety of launch conditions.

Performance of polarization-maintaining single-mode optical fiber for IFOG applications

An account is given of the design parameters of the polarization-maintaining single-mode optical fibers currently under development for incorporation in interferometric FOGs (IFOGs). Attention is given to a fiber design that satisfies IFOG requirements; optical performance parameters that encompass coil and splice results are presented. The polymer coating is found to play a substantial role in the maintenance of coil performance over a range of temperatures.

Design and Characterization of Optical Waveguides for Gyro Applications

Polarization retaining single-mode fibers are being developed using the stress-rod approach. Design parameter values have been varied to optimize birefringence, polarization holding, and low attenuation rates. Test configurations have been developed to characterize the fibers under simulated deployment bending conditions. The results show that good polarization and attenuation properties can be maintained for long lengths of fibers wound into compact sensor configurations.