An Experimental Study on Chirp Noise in a Directly Modulated Semiconductor Laser


IEICE TRANSACTIONS on Communications   Vol.E81-B   No.6   pp.1197-1202
Publication Date: 1998/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Optical Communication
semiconductor laser diode,  direct modulation,  chirp noise,  fiber transmission,  

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The chirp noise effect in a directly modulated semiconductor laser diode (LD) is experimentally studied. A previous theoretical study reported that, when an LD is directly modulated, turn-on jitter caused by spontaneous emission, combined with chromatic dispersion, becomes a source of noise in fiber transmission and restricts system performance. This paper points out that, on the contrary, imperfection in LD driving circuits causes chirp noise and limits transmission performance in actual systems. Experiments regarding dependence of chirp noise on LD modulation conditions are also presented, which show that a high relaxation oscillation frequency and a short turn-on delay time are preferable from the viewpoint of chirp noise.