Use of Predistortion to Reduce Intermodulation Distortion in Optical Fiber Communication Sources.
Abstract
Optical fiber communication is a new technology which has the potential of surpassing conventional communication techniques in many applications. One problem area is the introduction of distortion produced by nonlinearities in the system. Light-emitting diodes, used as sources in optical communication systems, are the main contributors of the nonlinearities. A procedure for compensating for the nonlinearity of an LED is developed. An optical receiver and LED transmitter were constructed to measure the light intensity vs LED current characteristic of various LEDS. The static and dynamic characteristics of each of the LEDS were measured. A polynomial describing the dynamic characteristic is used to predict the intermodulation distortion vs percent modulation. Measurements of the intermodulation components of the received signal at different depths of modulation show a close correlation to the calculated values. A predistortion approach to compensating for the nonlinearity of the LED is pursued. Using the LED characteristic, a means of determining the parameters of the compensating network is sought. These parameters are used and measurement of the overall linearity of the system is again checked and compared to that of the uncompensated system.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1979
- Accession Number
- ADA072637
Entities
People
- Donald A. Smith
- Gary L. Larson
Organizations
- North Dakota State University