A modified carrier suppressed return-to-zero (CSRZ) format was forward in this paper, and it helps to improve the extinct ration (ER) and signal-to-noise ration (SNR) of the transmitted signal. Experiment of 2560km error-free transmission in straight line without forward error correction (FEC) and electric regeneration was demonstrated in this paper to evaluate the performance of modified CSRZ, and chirped fiber Bragg grating (CFBG) employed as the dispersion compensator in this transmission system. The experiment
result showed that if the modified CSRZ format was applied in this 2560km transmission, less than 2.5dB power penalty was cost after 2560km transmission, and on the other hand, error-free transmission could not be got in the conventional NRZ-based CFBG-compensated system.
Kanakidis <i>et al</i> presented several kinds of all-optical chaotic communication systems using two encoding techniques and various dispersion compensation maps . It shows that the permitted transmission distances are different for various dispersion compensation maps and various encoding techniques. In order to explore the upper limits of the transmission distance, the parameters of the all-optical chaotic communication system introduced by D. Kanakidis <i>et al</i>.  is optimized using genetic algorithm. Some useful results are presented.
Using dispersion compensation CBG, 2500km-10Gbps RZ and CSRZ transmission system on G.652 fiber is successfully demonstrated without electric regenerator and without Raman amplifier. At 2080km and 2560km, power penalty for RZ is about 3dBm and 5dBm (condition: RZ signal, BER=10<sup>-12</sup>, PRBS=10<sup>23-1</sup>); And power penalty for CSRZ is about 1dBm and 3dBm. The result indicates it is superior to the system using CSRZ signal under same condition.
Group velocity delay ripple (GDR) and reflectivity ripple (RR) are the main nonideal characteristics for chirped Bragg fiber grating (CFBG). The influence of these nonideal characteristics on the CFBG-based transmission systems with carrier suppressed return-to-zero (CSRZ) format was investigated, and the performance of the transmission system was evaluated by the eye opening penalty (EOP) in this paper. In additional, the impact of the phase difference between the central wavelength of the transmitted signal and the GDR on the transmission system which make the transmission performance fluctuate randomly was also studied. The analysis helps to conduct a practical 10Gb/s 2560km error-free transmission experiment in straight line with low power penalty, and no electronics regenerator and forward error correction (FEC) were employed in this system. The experiment result is so attractive in long haul transmission field.
Bragg fibres have many special characteristics. Therefore this kind of fibre attracts more and more attention. In this paper, genetic algorithm is applied to design Bragg fibres to realise desired dipersion and attenuation characteristics.
A novel widely tunable fiber laser which can rapidly select the desired ITU-T wavelength has been proposed. This multiwavelength source, based on vernier caliper component(two sampled fiber Bragg gratings with a slight different in channel separation) appears very promising for wavelength division multiplexing since which has many advantages such as a widely tuning range of selective wavelength, easily lock to the wavelength separation, cheap costly, stable performance and so on.
In this paper, we demonstrate a chirped grating designed to compensate for both second- and third-order fiber dispersion. The fabrication technique of chirped gratings is the phase-mask beam scanning method by using a standard unchirped phase mask and by tapering a fiber in the region of the grating. We have made theoretical analysis on the chirp induced by linear and nonlinear taper profiles. The reflectivity and time delay curve of such fiber Bragg grating have been calculated.