In this research, phosphorescent SrAl₂O₄:Eu²⁺, Dy³⁺ fibers were produced by electrospinning and coated with atomic layer deposition (ALD) technique to enhance the photoluminescence (PL) properties, and water & thermal resistance. Particle form of Eu²⁺-activated strontium aluminate phosphors possess many remarkable features that have been reported over and over, for example, nontoxic, stable, efficient. PL enhancement and stability in water of these particles were provided by nano encapsulation process by ALD that has just been published in our previous paper. In this study, for the first time, SrAl₂O₄ based long persistence phosphor fibers were coated with the ALD method to both improve their PL and provide water & thermal resistance property. In this successfully carried out study, luminescence, optic, chemical and structural properties of phosphor in fiber form were investigated in detail. These improved submicron afterglow fibers which are SrAl₂O₄:Eu²⁺, Dy³⁺ based are promising materials for applications such as solar cells, luminescent labels for bioimaging, mechanoluminescence sensor, etc.