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Proceedings Paper

Accurate Measurement Of The FM Response In Magnitude And Phase Of Different DFB Laser Structures
Author(s): Piero Gambini; Nunzio P. Caponio; Mario Puleo; Emilio Vezzoni
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Paper Abstract

Characteristics and problems of laser diode FM response, strongly affecting coherent optical transmissions with FSK modulation, are briefly reviewed. A measurement set up, that is based on the use of a plane mirror Fabry-Perot resonator as a frequency discriminator, and that allows accurate measurement of laser FM characteristics, is described. A thorough survey has been carried out on a group of fourteen commercial DFB laser diodes, with five different structures, and relevant results are presented here. Significant FM response distortion, both in amplitude and phase, has been found, mainly concentrated in the range 0.1-10 MHz. From a system point of view, this calls for either equalization circuits or transmission codes with small energy content at low frequency, where the distortion is higher. Yet, although common features can be roughly recognized, it is very difficult to identify, a "typical" behaviour, due to the large dispersion of results, even inside the same class of devices. This means that, with present DFB laser diodes, the equalization approach does not seem practical, since individual tailoring of the equalization to each laser would be necessary. As a result of this investigation, the introduction of proper transmission codes (AMI, CMI,...) seems therefore the only realistic solution, at least at present.

Paper Details

Date Published: 5 February 1990
PDF: 12 pages
Proc. SPIE 1175, Coherent Lightwave Communications: Fourth in a Series, (5 February 1990); doi: 10.1117/12.963262
Show Author Affiliations
Piero Gambini, CSELT (Italy)
Nunzio P. Caponio, CSELT (Italy)
Mario Puleo, CSELT (Italy)
Emilio Vezzoni, CSELT (Italy)

Published in SPIE Proceedings Vol. 1175:
Coherent Lightwave Communications: Fourth in a Series
Roger C. Steele; Harish R. Sunak, Editor(s)

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