| Summary: | 碩士 === 國立中山大學 === 光電工程研究所 === 90 ===
Abstract
In this paper, we build up the DRA (Distributed Raman Amplifier) by using four pump LDs (1460nm, 1470nm, 1480nm, 1490nm) with 25km LEAF (Large Effect Area Fiber) to transmission and compared the performance with system that just have EDFA. For the long distant system, we use EDFA and DRA to transmit 80km LEAF. In order to increase the system power budget it is necessary to use the two optical amplifiers in the same time.
For the experimental results, we find that use the Raman amplifier with 25km LEAF may have degradations of CNR, CSO, CTB with 1~2 dB, 2 dB and 2~3 dB compared to Back-to-Back configuration, consider the reasons for the CSO and CTB degradations are due to the fiber dispersion and nonlinearly effect (SPM) in transmission process, and the pumps generate the high Raman spontaneous emission and source spontaneous emission are the main reasons to degrade CNR. We try to find the pump laser which effects signal noise largest (1460 nm LD) and turned off it, then CNR have about 0.5~1.0 dB improved.
In the long distant transmission pass through 80km LEAF, the performances of CNR, CSO, CTB have serious decay. Because of the ASE generated from EDFA and Raman spontaneous emission and source spontaneous emission generated form Raman amplifier accumulate each other to made the CNR decay. For the long distance fiber dispersion and fiber nonlinear effect (SPM) also made CSO, CTB have degradations in the system, the CNR is about 45.2~47.3 dB, CSO is about 72.3~75.9 dBc , CTB is about 67.4~71 dBc. For this result, we know that DRA is not suitable applied in analog CATV system for the serious degradation of CNR. The study may give a reference to discuss Raman amplifier in the analog CATV system in the future.
|
|---|
