|
Document Type |
: |
Thesis |
|
Document Title |
: |
Performance of high speed laser diodes in optical fiber communication systems أداء ليزر الوصلة عالي السرعة في أنظمة اتصالات الألياف الضوئية |
|
Subject |
: |
physics department |
|
Document Language |
: |
Arabic |
|
Abstract |
: |
Directly modulated high-speed semiconductor lasers are of great interest for low-cost 40-Gbps short reach fiber communication systems. However, the high-speed modulation is associated with a large shift of the lasing frequency (chirp), which works with fiber dispersion to limit the fiber system performance. In this thesis, the modulation characteristics of high-speed lasers under 10 and 40 Gbps modulations are introduced, and their performance in fiber communication systems is quantified. The study includes the return to zero (RZ) and non-return to zero (NRZ) patterns of the pseudorandom modulation bits. The modulation characteristics of the laser include the eye diagram and the frequency chirp. The performance of the fiber system is assessed by the fiber length limitation by both the fiber attenuation and dispersion. Improvement of the fiber system performance by replacing standard single-mode fibers by non-zero dispersion-shifted fibers is examined.
The obtained results indicate that the modulation bandwidth of the laser increases to a value as high as 24.2 GHz when the differential gain is increased to 9.9x10-20cm2. Under 10-Gbps modulation, the transient chirp is ~ 62.7 GHz and is independent of the bit pattern. The chirp increases to 65.1 and 72.8 GHz under 40-Gbps modulation for the RZ and NRZ patterns, respectively. In the 10-Gbps fiber system, the fiber length is limited by the fiber attenuation to 81.51 and 78.48 km and by the dispersion to 17.06 and 9.30 km under the RZ and NRZ patterns, respectively. In the 40-Gbps fiber system, these fiber lengths decrease more to 2.51 and 1.37 km under the RZ and NRZ patterns, respectively. When the dispersion parameter is reduced from 16.75 to 4.5 ps/nm/km in non-zero dispersion-shifted fibers, the fiber length increases to 9.14 and 4.78 km under the RZ and NRZ patterns, respectively, which correspond to short-reach transmission networks. The power penalty associated with the variation of the fiber dispersion is too much enhanced around zero dispersion. This power penalty drops too much apart from the vicinity of the zero dispersion. The RZ-pattern induces power penalty higher than the NRZ pattern. New dispersion tolerances were explored for 1-dB power penalty of the RZ and NRZ fiber communication systems. |
|
Supervisor |
: |
Dr. Moustafa Farghal Ahmed |
|
Thesis Type |
: |
Master Thesis |
|
Publishing Year |
: |
1435 AH
2013 AD |
|
Co-Supervisor |
: |
Dr. Ahmed Hamood Ali Bakry |
|
Added Date |
: |
Wednesday, January 29, 2014 |
|
Researchers
| فوزيه ثبات البلادي | Albeladi, Fwoziah Thabat | Researcher | Master | |
|