Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology
We investigate the dynamics and noise of semiconductor lasers (SLs) subject to analog modulation with the frequency plan of the National Television Standards Committee (NTSC) for use in the community access television (CATV) systems. The investigations are done in both the time and frequency domains...
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2015-06-01
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doaj-daea715e1a4e4472987ca00ef9f847c02020-11-25T01:46:40ZengSpringerOpenBeni-Suef University Journal of Basic and Applied Sciences2314-85352015-06-01429910810.1016/j.bjbas.2015.05.002Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technologyAlaa Mahmoud0Safwat W.Z. Mahmoud1Kamal Abdelhady2High Institute for Engineering and Technology, El-Minia, EgyptDepartment of Physics, Faculty of Science, Minia University, 61519 El-Minia, EgyptDepartment of Physics, Faculty of Science, Minia University, 61519 El-Minia, EgyptWe investigate the dynamics and noise of semiconductor lasers (SLs) subject to analog modulation with the frequency plan of the National Television Standards Committee (NTSC) for use in the community access television (CATV) systems. The investigations are done in both the time and frequency domains as important methodologies to upgrade the optical CATV systems. The study is based on the rate equation model of the laser. The modulation dynamics is classified into four distinct types according to the waveform of the modulated signal, and the frequency spectra of the relative intensity noise (RIN) of these types are characterized. We show that the laser emits continuous and regular period signals under weak modulation. When the modulation index exceeds 43%, i.e. the modulation current exceeds the bias level above threshold, the laser emits clipped signals superposed by relaxation oscillation. The increase in the modulation index by about 50% in channels beyond channel #24 makes the laser emitting clipped pulsed signals superposed by relaxation oscillation. The laser attains higher noise levels (∼−108 dB/Hz) when it emits pulses, whereas the noise is lowest (∼−170 dB/Hz) when the signal is continuous.http://www.sciencedirect.com/science/article/pii/S2314853515000232Semiconductor laser diodeCATV systemNTSC channel planDirect analog modulationModulation dynamics |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Alaa Mahmoud Safwat W.Z. Mahmoud Kamal Abdelhady |
spellingShingle |
Alaa Mahmoud Safwat W.Z. Mahmoud Kamal Abdelhady Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology Beni-Suef University Journal of Basic and Applied Sciences Semiconductor laser diode CATV system NTSC channel plan Direct analog modulation Modulation dynamics |
author_facet |
Alaa Mahmoud Safwat W.Z. Mahmoud Kamal Abdelhady |
author_sort |
Alaa Mahmoud |
title |
Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology |
title_short |
Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology |
title_full |
Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology |
title_fullStr |
Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology |
title_full_unstemmed |
Modeling and simulation of dynamics and noise of semiconductor lasers under NTSC modulation for use in the CATV technology |
title_sort |
modeling and simulation of dynamics and noise of semiconductor lasers under ntsc modulation for use in the catv technology |
publisher |
SpringerOpen |
series |
Beni-Suef University Journal of Basic and Applied Sciences |
issn |
2314-8535 |
publishDate |
2015-06-01 |
description |
We investigate the dynamics and noise of semiconductor lasers (SLs) subject to analog modulation with the frequency plan of the National Television Standards Committee (NTSC) for use in the community access television (CATV) systems. The investigations are done in both the time and frequency domains as important methodologies to upgrade the optical CATV systems. The study is based on the rate equation model of the laser. The modulation dynamics is classified into four distinct types according to the waveform of the modulated signal, and the frequency spectra of the relative intensity noise (RIN) of these types are characterized. We show that the laser emits continuous and regular period signals under weak modulation. When the modulation index exceeds 43%, i.e. the modulation current exceeds the bias level above threshold, the laser emits clipped signals superposed by relaxation oscillation. The increase in the modulation index by about 50% in channels beyond channel #24 makes the laser emitting clipped pulsed signals superposed by relaxation oscillation. The laser attains higher noise levels (∼−108 dB/Hz) when it emits pulses, whereas the noise is lowest (∼−170 dB/Hz) when the signal is continuous. |
topic |
Semiconductor laser diode CATV system NTSC channel plan Direct analog modulation Modulation dynamics |
url |
http://www.sciencedirect.com/science/article/pii/S2314853515000232 |
work_keys_str_mv |
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