Wide-Range Tunable Optical Delay Line Using Dual Concentric Core Fiber With Dispersion Coefficient of ${-}$ 2800 ps/nm/km

There is great interest in finding a way to control the propagation speed of optical pulses through a medium. A pulse delay control technique that uses a dispersive medium and wavelength conversion has attracted a lot of attention because it is transparent as regards the format or bit rate of incoming signals. However, a long length of fiber is needed to obtain a sufficient delay in the delay line. In this paper, we propose a tunable optical delay line with a highly dispersive dual concentric core fiber (DCCF) that enables us to obtain a large time delay efficiently. The fabricated DCCF has a minimum dispersion of - 2800 ps/nm/km, and has the potential to generate a 54 ns/km delay by employing wavelength conversion within the C-band. We also evaluate the signal quality by measuring the bit error rate characteristics of the delayed signals through the proposed delay line.