A Novel Trench-Assisted Optical Fiber With Ultra-Low Microbending Loss for the Full Ocean Depth Communication

A novel trench-assisted optical fiber with ultra-low microbending loss is proposed, which contains two trenches beside the core. The deformation distribution of the fiber axis caused by the wire mesh is in agreement with a Gaussian curve through the mechanical-optical model. By analyzing the microbending loss dependency on the optical fiber parameters, the optimal structure for the trench-assisted optical fiber was obtained. The fundamental mode field characteristics of the designed fiber under microbending were simulated using the finite element method, and the energy ratio of the designed fiber was obtained as 95.03%, which is larger than that of the conventional single-mode fiber. The designed fiber was fabricated based on the modified chemical vapor deposition (MCVD) technique and tested according to the modified plate method. The experimental results indicate that the fabricated fiber can support an ultra-low microbending loss of 0.0052 dB/m at 6 kg weight at 1550 nm, which is reduced by two orders of magnitude compared to the conventional single-mode fiber. The microbending loss measurement system exhibits good reliability and repeatability, and the measured results are consistent with the theory. The proposed optical fiber will be beneficial in improving the transmission efficiency of full ocean depth communication.