The Optimal Design of Hybrid Raman/EDF Amplifiers for WDM System

• Main Authors: Yen-Han Tung, 童彥涵
• Other Authors: Jeng-Cherng Dung
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/52000008806943063681

碩士 === 國立東華大學 === 電機工程學系 === 99 === We demonstrate the characteristics of the hybrid optical fiber amplifiers in considering net gain, noise figure (NF) and stimulated Brillouin scattering (SBS) induction penalty. The gain media of C-band and L-band are erbium-doped fiber (EDF) and dispersion compensating fiber (DCF), respectively. First, the gain media are series and the signals can be amplified at EDF and DCF, respectively (One Pass). Then, we add the optical circulator and the Faraday rotator mirror. The configurations can make the reflected lights make a second pass through the gain medium (Double Pass). But the Stimulated Brillouin Scattering (SBS) induces penalty. We adjust pumping to reduce the SBS penalty, then show the comparison of the One Pass and Double Pass configurations, respectively. First, we measure signal gains of one pass configuration. The pump soureces consists of four laser diodes operating at 1480 and 1510 nm, respectively. The pump power is launched into the gain medium fiber from each pumping laser diodes as an one-stage configuration. According to the signals amplified at the DCF or the EDF first and through the different direction of the pumping, we design four configurations. The configuration having the signals amplified at EDF first with backward pumping gets the best performance. The signal gains of C-band and L-band are 20.7~27.9 dB and 22.3~25.2 dB, respectively. It is not a gain-flattened fiber amplifier although the gain value is not so bad. Then, we measure the signal gains of double pass configuration. We design four configurations according to the gain-flattened characteristics. The configuration of the signals amplified at EDF first and then amplified at DCF twice with backward pumping (HFA Double Pass TypeⅣ) is the best performance. The gain-flattened performance of the Double Pass configuration is better than that of the One Pass configuration. However, both methods produce the SBS induction penalty. The SBS can decrease the net gain and increase the NF. We adjust pumping to reduce the SBS penalty, then show the comparison of the One Pass and Double Pass configurations, respectively. As a result, the HFA Double Pass TypeⅣ configuration still has the best performance with input signal power of -20 dBm. This amplifier can provide the net gain of 18.3~23.3 dB at C-Band and 18.9~21.9 dB at L-Band, respectively. But when the signals power increase, the SBS penalty limits the functioning of amplifier. The configuration of the signals amplified at DCF first and then amplified at EDF with backward pumping is the best performance. The gain-flattened performance of the One Pass configuration is better than that of the Double Pass configuration. The signal gains of 1530~1570 nm and 1570~1610 nm are 15.7~20.5 dB and 12.2~15.5 dB, respectively. This amplifier design has the advantages of high gain, low NF and gain flattened characteristics at low signal level. It has been proved by this study to be better than the exsiting in-line and pre amplifier.