Twisted Few-Mode Optical Fiber with Improved Height of Quasi-Step Refractive Index Profile

Area of Science:

• Optoelectronics
• Materials Science
• Optical Communications

Background:

• Few-mode optical fibers (FMFs) are essential for increasing optical communication capacity.
• Controlling the number of guided modes is critical for FMF performance.
• Silica-based FMFs offer a promising platform for next-generation networks.

Purpose of the Study:

• To design and fabricate a silica few-mode optical fiber (FMF).
• To support a specific number of guided modes (4 modes) over the C-band.
• To investigate the impact of fiber parameters on mode support and few-mode effects.

Main Methods:

• Fabrication of silica FMF with controlled core diameter (11 µm) and numerical aperture (0.22).
• Introduction of twisting (10 and 66 revolutions/meter) to influence fiber properties.
• Experimental characterization including spectral response measurements of laser-excited signals.
• Analysis of few-mode effects after fiber Bragg grating inscription.

Main Results:

• Successfully designed and fabricated silica FMF supporting 4 guided modes in the C-band.
• Optimized fiber parameters including refractive index profile and twisting.
• Demonstrated experimental measurement of spectral responses and few-mode effects.

Conclusions:

• The designed silica FMF meets the requirements for supporting a limited number of modes.
• The study provides insights into parameter selection for FMF design.
• The fabricated FMF shows potential for applications in advanced optical communication systems.