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An electrochromic variable optical attenuator(ECVOA) was fabricated by layer-by-layer(LBL) assembly of disodium N,N-bis(p-sulfonatophenyl)naphthalenedicarboximide(Naph-SO_3Na) and common cationic polymer poly(diallyldimethylammonium) chloride(PDDA).The UV-Vis absorption spectra of the multilayer films revealed that approximately an equal amount of Naph-SO_3Na was assembled in each deposition cycle.Upon one-electron reduction, multilayer films exhibited intense absorption around 452 nm and also a broad absorption band from 1200 nm to 1900 nm. Owing to the improved ionic conductivity,the optical attenuation at 1550 nm of the films showed rapid response time and reached 1.3 dB/μm within 5 s.These results indicate that layer-by-layer assembly could be an effective method for the preparation of ECVOA operating in near infrared region.