Objective: During root canal or periodontal treatment, directing laser energy onto the walls of the root canal is essential for effective disinfection. This study assessed the performance of three designs of fiber modifications that modified to allow the laser beam skip in lateral direction to be used in endodontic applications and investigated the irradiation effects on the walls on root canal using scanning electron microscope in comparison to that irradiation using the endodontic fiber optic provided by manufacturer. Material and Methods: twenty fiber optic subdivide into two main groups as conventional endodontic 200 µ tips and the second group was 400µ fiber optic that modified into 3 designs of modification as one, two and three windows. all fiber optics was used in irradiation of endodontically cleaned natural teeth and scanned by SEM. Result: there was a significant difference between the irradiated teeth by the proposed modified fiber optics in comparison to that irradiated by the conventional endodontic fiber optic tips Conclusion: Fiber designs with lateral emission capabilities may be useful for various endodontic applications.