A Comparison of Differential Mode Delay Measurements on Multimode Fibers in the Time and Frequency Domains Brackets Indicate omission in Final Paper

Published

September 1, 1998

Author(s)

John B. Schlager, Douglas L. Franzen

Abstract

Multimode fiber bandwidth is currently measured using an overfilled launch condition. Such a launch is achieved by uniformly exciting the core and launching with a numerical aperture (NA) that exceeds the NA of the fiber.¹ This launch provides a reprocible way to predict the bandwidth performance of LED-based fiber networks. New high-speed fiber networks, however, take advantage of the faster modulation capabilities of laser sources like vertical cavity surface emitting lasers (VCSELs) and Fabry-Perot lasers. These sources typically underfill the avialable mode volume of the fiber. In most cases these underfilled or restricted laser launches give bandwidth performances that meet or exceed the bandwidth performances predicted with overfilled launches. The specific behavior, however, depends on the differential mode delay (DMD) of the fiber's refractive index profile. We have developed a frequency-domain DMD measurement system with a temporal resolution of 0.2 ps. This represents a more than 50 times improvement over more conventional time-domain DMD measurement systems.² The new system allows accurate DMD measurements on shorter fiber samples, and the DMD results compare well with those obtained using the time-domain technique.

Conference Dates

September 15-17, 1998

Conference Location

Boulder, CO, USA

Conference Title

Symposium on Optical Fiber Measurements

Pub Type

Conferences

Keywords

differential mode delay, frequency-domain, graded-index multimode fiber

Citation

Schlager, J. and Franzen, D. (1998), A Comparison of Differential Mode Delay Measurements on Multimode Fibers in the Time and Frequency Domains Brackets Indicate omission in Final Paper, Symposium on Optical Fiber Measurements, Boulder, CO, USA (Accessed July 27, 2024)