Fig. 1. (a) Schematic of modes exchange; (b) mode exchange sequence between LP01, LP11a, LP11b, and LP21 modes; (c) calculated images of the phase planes; (d) microscopic images of the fabricated phase masks.

Fig. 2. (a) Schematic diagram of the reflective mode exchange device; (b) physical image of the device; (c) intensity distribution of the calculated modes; (d) phase distribution of the calculated modes; (e) intensity distribution of the generated modes by the modes exchange device; (f) phase distribution of the reconstructed modes; (g) calculated and (h) experimental mode crosstalk gray matrices.

Fig. 3. Conversion efficiency of the mode exchange device over the C-band and the L-band wavelengths.

Fig. 4. (a) Experimental setup of the few-mode optical fiber communication system based on mode exchange device; (b) measured mode crosstalk gray matrices of the communication system; (c) measured BER characteristics of the system. Constellation diagrams of the QPSK signals: (d) LP01 mode; (e) LP11 mode; (f) LP21 mode.