Quantum Intensity Noise of Directly Modulated Laser Diode Influenced by Reflected Waves

Osamu HIROTA  Yasuharu SUEMATSU  

IEICE TRANSACTIONS (1976-1990)   Vol.E65   No.2   pp.94-101
Publication Date: 1982/02/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Optical and Quantum Electronics

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The noise properties of directly modulated laser diode influenced by reflected waves are given theoretically. Firstly, the quantum noise enhancement effect due to direct modulation is found theoretically in term of product between the quantum shot noise and the modulation current. Secondly, the high-frequency intensity noise due to reflected waves (often so-called self-coupling effect) is clarified to be due to resonance of the quantum shot noise to the external cavity. According to our theory, it is found that the noise of the narrow stripe laser diode with the stripe width comparable to the diffusion length of carrier is about 10 dB smaller than that of the wide stripe laser. And also, the reverse isolation loss of an optical isolator is estimated theoretically to be 30 dB to reduce the relative high-frequency intensity noise by 40 dB.