Analysis of Transient Spectral Spread of Directly Modulated DFB LD's

Takeshi KAWAI  Atsutaka KURIHARA  Masakazu MORI  Toshio GOTO  Akira MIYAUCHI  Takakiyo NAKAGAMI  

IEICE TRANSACTIONS on Communications   Vol.E76-B   No.6   pp.677-683
Publication Date: 1993/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Optical Communication
optical communication,  opto-electronics,  distributed feedback laser,  subpeak,  

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The transient spectral spread of directly modulated DFB LD's, which appears in the time-resolved chirping measurement, is studied experimentally and numerically. Such a phenomenon has been already reported as a side mode oscillation called "subpeak", but there has been little argument as to the physical origin. We make it clear that the subpeak is a spurious mode due to the influence of the photodetector bandwidth. The minimum photodetector bandwidth which is necessary in the time-resolved chirping measurement is examined. Furthermore the distortion of the long-distance transmitted waveform is also explained by one mode oscillation.