[Objective]The optical fiber dispersion,nonlinear impairments and bandwidth limitation in high-speed passive optical access networks lead to high power budget loss in traditional intensity modulation and direct detection schemes,which are diffi-cult to meet the requirements of future high-speed passive optical access networks.[Methods]In order to improve the speed and performance of the intensity modulation and direct detection optical access system,based on the Volterra Decision Feedback E-qualizer(VDFE),this article studies the channel equalization method of VDFE-RLS based on Recursive Least Squares(RLS)algorithm.This equalizer uses RLS algorithm to update the tap coefficients.The equalizer includes a three-order Volterra se-ries,allowing it to compensate for both linear and nonlinear impairments.In this paper,VDFE-RLS is applied to the downlink optical access system with a single wavelength 200 Gbit/s based on O-band intensity modulation and direct detection scheme af-ter 20 km transmission.[Results]The experimental results show that the RLS has better performance than conventional Least Mean Square(LMS)algorithm in the equalization process.Besides,VDFE-RLS can achieve a power budget greater than 29 dB.When the length of the equalizer is the same,VDFE-RLS can increase the power budget by 2.2 dB compared with the conventional Volterra Feed Forward Equalization(VFFE)-RLS equalizer.When the length of VDFE-RLS equalizer is half that of VFFE-RLS,the VDFE-RLS can increase the power budget by 0.5 dB compared with the VFFE-RLS equalizer.[Conclu-sion]Compared with other traditional methods,the proposed method can shorten the length of the equalizer and increase the power budget of the system,and finally recover the signal with better performance.
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