Low-DMD few-mode fiber with distributed long-period grating

Area of Science:

• Optical Fiber Communications
• Photonics
• Materials Science

Background:

• Differential Mode Delay (DMD) is a major challenge in few-mode fiber (FMF) systems, limiting data transmission capacity.
• Existing methods for DMD mitigation often involve complex structures or limited operational ranges.
• Few-mode fibers are crucial for next-generation high-capacity optical networks.

Purpose of the Study:

• To propose and investigate a novel distributed grating-assisted few-mode fiber (DG-FMF) for effective DMD reduction.
• To demonstrate the feasibility of using asymmetric long-period fiber gratings for mode coupling in FMFs.
• To ensure DMD reduction across the C-band and a wide temperature range.

Main Methods:

• Fabrication of a step-index few-mode fiber incorporating asymmetric long-period fiber gratings with random exposure.
• Introduction of strong random mode coupling along the fiber length via precisely engineered gratings.
• Numerical simulations to evaluate the performance of the DG-FMF in terms of DMD reduction.

Main Results:

• Simulated mean DMD reduced to below 12 ns over 100 km for DG-FMF with a 514 μm period and 1x10^-6 grating strength.
• Effective DMD reduction demonstrated across the entire C-band (1530–1565 nm).
• Consistent performance maintained over a wide temperature range (-20°C to +60°C).

Conclusions:

• The proposed DG-FMF effectively mitigates differential mode delay.
• This fiber design offers a robust solution for high-capacity optical communication systems.
• DG-FMF technology shows potential for reliable performance in diverse environmental conditions.