Connecting Circular Tube Based Extremely Low Loss and Wideband Negative Curvature Fiber

This article introduces a new concept for negative curvature fiber with an elliptical cladding arrangement that incorporates connecting circular tubes. This special design aims to enhance the loss performance of the fiber by generating extra negative and positive curvature layers in cladding elements. As a result, the fiber achieved lower leakage loss and better operating bandwidth, bending loss, and single mode performance over its round or oval tube counterparts. The fiber shows the ability to cover the whole telecom spectrum, hence, the leakage loss at 1.31 μm and 1.55 μm, respectively, is found as 0.0006 dB/km and 0.001 dB/km, which is the lowest leakage loss as far as we know in case of negative curvature fiber. Additionally, the proposed fiber provides an extremely broad bandwidth of 420 nm by sustaining a leakage loss of < 0.01 dB/km. Further, we show that the whole band exhibits a small bending loss of 0.01 dB/km at 4 cm bend radii. The study also finds a higher order mode extinction ratio of 101000 at 1.55 μm, which effectively retains the performance of the single mode at a satisfactory level. The proposed fiber’s ability to transmit signals over a broad range of wavelengths with little loss of signal strength makes it highly suitable for installation in optical communication networks.