All-optical Wavelength Conversion For Mode-division Multiplexing Signals Using Four-wave Mixing In Fiber

Multiplexing technology is an efficient way to improve transmission capacity in fiber communication system, such as wavelength-division multiplexing, time-division multiplexing and polarization-division multiplexing. Recently, mode-division multiplexing that utilizes different modes as different signal channels in fibers or waveguides has received a wide spread attention.In this paper, we present a scheme to realize all-optical wavelength conversion for mode-division multiplexing (MDM) signals in future all-optical communication system by converting the two signal modes simultaneously using four-wave mixing (FWM) in a dual-mode fiber incorporating a pump with two modes (LPoi and LPn). Firstly, the FWM effects among the dual-mode pump and signal are theoretically analyzed. And then, the structure and refractive index distribution of dual-mode fiber is optimized according to the required dispersion performance determined by the phase-matching conditions. By using the optimized dual-mode fiber, an effective conversion bandwidth, which refers to the wavelength region where the conversion efficiency drops less than 3 dB and the signal-to-crosstalk ratio (SCR) is greater than 15 dB, of 69.3 nm is numerically obtained with a conversion efficiency of -4.7 dB. This paper gives a theoretical foundation for all-optical MDM signal processing.