The Study of Broadband and Gain Flatten double-pass Raman Amplifier in Dispersion Compensating Fiber using Multi-Wavelength Pumping and Residual Pump Power for Increased Efficiency

• Main Authors: Yu-Hsiang Wen, 溫裕翔
• Other Authors: Jeng-Cherng Dung
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/19147554517217888996

碩士 === 國立東華大學 === 電機工程學系 === 97 === In this thesis, because the short dispersion compensation fiber (DCF) length reduces the amount of available gain for a given amount of pump power in the double-pass dispersion compensation Raman amplifier (double-pass DCRA), we proposed double-pass DCRA with pump-reflector. The circulator loop composed of an optical circulator used as pump-reflector so as to recycle residual Raman pump for increase efficiency of the system. When input signal is -25dBm at 1550nm, Raman pump is 260mW at 1450nm, the net gain of the backward pumping double-pass DCRA increased 3.09 dB form 10.49 dB to 13.58 dB and NF decrease 0.35 dB form 7.18 dB to 6.83 dB by adding circulator loop. In addition, the forward pumping double-pass DCRA also increased 3.09 dB form 11.24 dB to 14.33 dB and NF decrease 0.3 dB form 6.55 dB to 6.25 dB by adding circulator loop. We successfully showed that the net gain can be increase and NF decrease of the double-pass DCRA by recycling residual Raman pump. Next, we compared the measured results of the backward pumping scheme with the forward pumping scheme, the net gain of the forward pumping scheme is higher than that backward pumping scheme about 0.75dB with the same components. In addition, the NF of the forward pumping scheme is lower than that backward pumping scheme about 0.58dB. We experimentally demonstrated that the proposed forward pumping scheme is better than the backward pumping scheme form the aspect of Raman gain and NF. And then, we applied the forward pumping double-pass DCRA with pump-reflector into the WDM system further. We compare the measured results of forward multi-pumping scheme with and without circulator loop. When the input signal power level of -25dBm, the results showed overall net gain increase 2.31dB, noise figure decrease 0.36dB and the gain ripple maintain less than ±0.81dB in the gain bandwidth of 52nm form 1533nm to 1585nm just by using 3 wavelength channels Raman pump including 1435nm, 1450nm and 1480nm. In addition, in the same gain bandwidth of 52nm, the proposed forward pumping scheme applied here is also better than the backward pumping scheme because the net gain is 0.59dB higher and the NF is 0.8dB lower with gain ripple ±0.81dB. Finally, we discussed the effects of double Rayleigh scattering/double Rayleigh back scattering (DRS/DRBS) on the above proposed structure by means of modified time-domain extinction method (MTEM). For the forward pumping double-pass DCRA, the multi-path interference (MPI) noise of with circulator loop scheme is lower than that of without circulator loop scheme.