Theoretical Studies of Low-Loss Optical Fibers.
Abstract
Extrinsic scattering coefficients (with values as great as 1 to 100 dB/m for any one of seven scattering processes) and extrinsic absorption coefficients beta sub ab (with impurity concentrations of either isolated impurity ions or molecules, or macroscopic inclusions as low as 0.001 to 0.0001 parts per billion giving beta sub ab = 0.01 dB/km) must be greatly reduced in order to attain an extinction coefficient beta sub ex = 0.01 dB/km = 2 x 10 to the minus 8th power/cm, which is extremely low, but is a fairly modest goal for low-loss fibers. There are only a few candidate glasses, and current fabrication techniques of crystalline fibers give extinction as great as five orders of magnitude greater than 0.01 dB/km. Attaining, maintaining, and even measuring the high purity in both crystals and glasses is expected to be difficult. Impurity-absorption spectra and peak-absorption wavelengths of both infrared and visible/ultraviolet absorption are tabulated for use in identifying troublesome impurities. Experimental absorption coefficients in the infrared region are tabulated to establish the state of the art. Single-crystal alkali halides may be rendered useless as low-loss fiber materials by surface imperfections (steps) and fracture, both induced by bending. Plots in intrinsic-scattering and absorption-coefficients, the so called V curves are useful in establishing the wavelength region in which intrinsic loss is negligible.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 15, 1980
- Accession Number
- ADA092264
Entities
People
- D. Mills
- M. Sparks
- R. Warren
- W. Fredericks