1 Laser and Optoelectronic Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq

2 Laser and Optoelectronic Engineering Department, Al-Naharain University, Baghdad, Iraq.

3 Laser and Optoelectronic Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.


Cascaded optical fiber single mode-no core-single mode fiber (SNS) attracted attention for being the base of various photonic devices. These devices are used in optical communication, fiber sensors, and fiber laser technology. The effect of variable NCF specifications, length, diameter, external refractive index (ERI), propagating wavelength on the self-imaging position, and the multimode interference (MMI) is studied. The study aims to simulate and analyze cascaded optical fiber by using the finite element beam envelope method (BEM). To the best of our knowledge, this is the first report that studied the self-imaging in cascaded optical fiber longitudinally by using BEM. The NCF length is important in determining the coupled out intensity and peak transmission wavelength. The field in the cascaded fiber is simulated for single and multi-wavelengths to evaluate the maximum transmission and study the structure's tunability. A tunable filter is simulated, where varying the length of the NCF about 0.6 mm produces a wavelength shift of about 40 nm. The BEM is effective in studying the field propagation in large guiding photonic devices

Graphical Abstract


  • · Multimode interference and self-imaging in the cascaded SNS fiber have been investigated numerically via COMSOL Multiphysics 5.5.
  • · To get high self-imaging quality, it is not necessary to be restricted to the rule of P = 4, 8...

            The BEM is effective in studying the field propagation in large guiding photonic devices.


Main Subjects

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