Different mechanisms of extrinsic losses, including aging, in extruded mixed AgClBr fibers are discussed. Additional losses caused by changes in structure of fiber material have been investigated. INTRODUCTION Mechanisms of optical losses in polycrystaffine fibers are still not clear due to theirs complicated dependence on a lot of various parameters of extrusion process and initial characteristics of crystalline preforms [1-4]. Aging effect is also determined by parameters of "fresh" fibers and by influence of environment conditions and way of fiber use. Our last studies were undertaken for better understanding of correlation between structure and optical losses in polycrystalline fibers extruded from crystals of solid solutions AgCI-AgBr. SPIE VoL 1591 Infrared Fiber Optics /11(1991) / 83 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/25/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx