Realization Of EDFA Automatic Calibration System Based On Vc++6.0

The Erbium-doped Fiber Amplifier(EDFA) is a type of important opticalcommunication device, and has been widely applied in fiber-optic communicationsystems. As one of the key components, high performance is required, such as sufficientgain bandwidth, low noise figure and automatic gain control(AGC) function. Accuracyof automatic gain control is one of the most important parametor to measure theperformance of EDFA. There are two methods to realize AGC: one is electric AutomaticGain Control (EAGC) and another is Optical Automatic Gain Control (OAGC). OAGChas increased the complexity and the cost of the system because it requires additionaloptical devices, which leads to its narrow usage. However, EAGC is a mainstreamsolution for AGC of commercial EDFA because of its mature technology and low cost.In this thesis, EDFA automatic calibration has been realized by EAGC. Automaticcalibration is to obtain the relationship between optical power and gain of the EDFA andthe sampled value of the control circuit through test, then establish corresponding linkedlists and finally download these lists to the memory of EDFA. When EDFA need toadujust gain atuomatically, it reads the current sampled value of pump through look-uptable control mechanism, then adjust the pump in order to lock gain quickly.A design project of automatic calibration system has been proposed in this thesisafter we have studied the principle of EAGC. According to the modularity design ofprogramming, automatic calibration system is classified into Prismatic Detector(PD)calibration, Variable Optical Attenuator(VOA) calibration, gain calibration, data fittingand validation modules. Then it analyzed and designd for each calibration process indetail based on the driving principle of the PD, VOA and pump laser. The linearinterpolation method of calibration data can be found out after analyzing the advantagesof look-up table control mechanism. Finally, based on the above calibration scheme, theautomatic calibration system is achieved, and then it helps to realize the automaticcalibration of EDFA successfully. The results showed that, the automatic calibration system which we designed in this paper can realize the AGC precisely, so the entiredesign has reached the requirements basically.