S. Al-Sowayan, Selective Excitation of Circular Helical Modes in Graded Index Fibers. journal = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology. November 2013, vol. 84(12). 1711 - 1713 [viewed 19 March 2024]. Available from: https://publications.waset.org/pdf/9996870.