Influence of pseudorandom bit format on the direct modulation performance of semiconductor lasers

Pramana

Moustafa Ahmed1 2²  Safwat W Z Mahmoud¹  Alaa A Mohmoud¹ 

[1] Department of Physics, Faculty of Science, Minia University, 61519 El-Minia, Egypt$$;Department of Physics, Faculty of Science, King Abdulaziz University, M.B. 20803, Jeddah 21589, Saudi Arabia$$

关键词: Chirp;    digital modulation;    eye diagram;    jitter;    semiconductor laser;    simulation.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

This paper investigates the direct gigabit modulation characteristics of semiconductor lasers using the return to zero (RZ) and non-return to zero (NRZ) formats. The modulation characteristics include the frequency chirp, eye diagram, and turn-on jitter (TOJ). The differences in the relative contributions of the intrinsic noise of the laser and the pseudorandom bit-pattern effect to the modulation characteristics are presented. We introduce an approximate estimation to the transient properties that control the digital modulation performance, namely, the modulation bit rate and the minimum (setting) bit rate required to yield a modulated laser signal free from the bit pattern effect. The results showed that the frequency chirp increases with the increase of the modulation current under both RZ and NRZ formats, and decreases remarkably with the increase of the bias current. The chirp is higher under the RZ modulation format than under the NRZ format. When the modulation bit rate is higher than the setting bit rate of the relaxation oscillation, the laser exhibits enhanced TOJ and the eye diagram is partially closed. TOJ decreases with the increase of the bias and/or modulation current for both formats of modulation.

【 授权许可】

Unknown