The Study In Gain Equalizer Of EDFA Based On The H-PDLC Gratnig

In fiber communications the shortcomings of EDFA (Erbium Doped Fiber Amplifier) maybe lead to the distortion. So it is necessary to equalize the gain spectrum. In the paper a novel method is presented that using the H-PDLC(Holographical- Polymer Dispersed Liquid Crystal) grating to flatten the gain spectrum and using the electro-optical properties of the H-PDLC grating to implement the dynamic equalization from to 0℃ to 65℃ have been successful in theory. Firstly the programs of Matlab language have been coded used GA to get the parameters of the grating to equalize the EDFA, then the parameters can guide the manufacture.The dynamic equalizer has much merit such as small volume, low cost, quick response, little power loss and good flatness. So the novel method that is easy to achieve has great practical value to study it. The results of the simulation have been got that on 1530~1560nm band-width from 0 ℃ to 65 ℃ the gain flatness has attained 0.2dBp-p, on 1525~1565nm band-width from 0℃ to 65℃the gain flatness has attained 0.45dBp_p and on 1520~1570nm band-width from 0℃ to 65℃ the gain flatness has attained 0.50dBp.p.On H-PDLC gratings, firstly the coupled-wave theory of the thick grating has been study, the formula to calculate the diffraction efficiency of the grating has been deduced and the characters of the grating have been simulated theoretically by Matlab language. Secondly the diffractive character of the grating incidence with the light of 632.8nm wavelength and 1550nm wavelength have been studied experimentally. Thirdly the electro-optical properties of the H-PDLC grating has been included.Finally the results of theory and experiment have been compared and the conclusion has been drawn that it is suitable to use the coupled-wave theory to explain the diffractive character of the grating.