This paper describes state-of-the-art techniques for characterizing dispersion in single-mode fibers. Special emphasis is placed on achieving high measurement accuracy within the 1.1-1.7 \mu m wavelength region.

Comparison of single-mode fiber dispersion measurement techniques

The role of the mode field diameter in the characterization of single-mode fibers is examined. The most relevant definitions of this parameter are reviewed, and a comparative analysis of methods for its measurement is performed. All the discussed measurement methods have reached a repeatability and reproducibility which are quite satisfying. Emphasis is given to the requirements posed by the new fiber designs, such as the polarization-maintaining structures. Most of the discussed techniques have been industrialized, and a number of instruments based on them are commercially available; however, it is predicted that the evolution of fiber design will impose new requirements on some of these instruments. >

Mode field diameter measurements in single-mode optical fibers

The design of monomode fibers is discussed in the context of optimizing fiber loss and dispersion simultaneously, with reference to the materials choices and limitations to preform and fiber fabrication by the MCVD technique. Two classes of monomode structure-matched cladding and depressed cladding-are considered. Ultralow attenuation has been achieved reproducibily in both classes of fiber. The control of fiber geometry and dispersion is also discussed. Matched cladding fiber suitable for systems operating at both 1.3 and 1.55 μm has been studied and mean losses of 0.45 dB/km at 1.3 μm and 0.28 dB/km at 1.55 μm have been achieved for a total of 130 km. The behavior of depressed cladding fiber is compared with predictions from the theory of propagation in W fibers. Depressed cladding fiber with stable guidance has been demonstrated with attenuation of 0.37 dB/km at 1.3 μm and 0.21 dB/km at 1.55 μm.

The design and fabrication of monomode optical fiber

A new technique for the measurement of constant-curvature (bend) loss as a function of bend radius is described, and it is shown that the influence of transition (microbend) losses can be essentially eliminated. Based on this technique and via the application of curve-fitting procedures and the Newton-Raphson method for two variables, a sensible equivalent step index can be obtained if stress-induced changes in the bent fiber are taken into account. However, the prediction of bend losses at other wavelengths is coarse, and it is shown that, for our fiber, agreement between theory and experiment can be considerably improved via an empirically deduced stress-induced dependence that is far stronger than predicted by published theory.

Constant-curvature loss in monomode fibers: an experimental investigation.

This review discusses the requirements and constraints on components for long-wavelength monomode systems. In particular it critically reviews the current status of fibre, splicing, cabling, laser, detector, receiver and systems research; emphasis is placed on practical achievements rather than just speculative possibilities. The review concludes with a brief assessment of the future role of guided-wave optical devices.

Components and systems for long-wavelength monomode fibre transmission

A new technique for measuring equivalent-step-index profiles of monomode fibres is presented which involves measuring the mode spot-size directly as a function of wavelength, and compares favourably with measured profiles. Since characterisation of the fibre is derived from easily measured optical properties, knowledge of the actual profile and the modelling of the propagation characteristics from it is unnecessary.

Direct method of determining equivalent-step-index profiles for monomode fibres

A modified method of fibre end-cleave angle measurement is described and compared with alternative techniques. The device has no precision parts and has a resolution of better than 0.25 degrees of end angle.

C.A. Millar

Papers

Direct method of determining equivalent-step-index profiles for monomode fibres

Simplified optical fibre end-cleave angle measurement device

Comment: Fundamental mode spot-size measurement in single-mode optical fibres