Fig. 1. Experimental setup of bidirectional MCF transmission system. The insets (a), (b), and (c) are the cross section view of the fabricated MCF, fan-in/fan-out, and picture of the whole fan-in/fan-out device, respectively. (OC, optical coupler; FI/FO, fan-in/fan-out; RX, receiver; Mux, multiplexer; DeMux, demultiplexer.)

Fig. 2. (Color online) Spectrum of 25 Gb/s OOK signal generated by DML1 with and without ODI, the transmission function of the ODI is also depicted. (w/o, without; w/, with; TF, transmission function.)

Fig. 3. (Color online) Frequency response of the transceivers with and without ODI. (BW, bandwidth.)

Fig. 4. Optical spectra of the WDM multiplexed 100 Gb/s OOK signals after ODI filtering.

Fig. 5. Measured eye diagrams for the OB2B case with and without ODI. (a)–(d) are for λ1∼λ4 without ODI, and (e)–(h) are for λ1∼λ4 with ODI, respectively.

Fig. 6. Measured eye diagrams of 25G OOK signals after 20 km MCF transmission. (a) λ1 in core 1 for the DS direction without ODI, (b) λ2 in core 5 for the US direction without ODI, (c) λ1 in core 1 for the DS direction with ODI, (d) λ2 in core 5 for the US direction with ODI.

Fig. 7. (Color online) BER performances of 100G OOK signals for different cores in bidirectional MCF transmission. (a)–(d) are for DS (core 1 and 2) and US (core 5 and 6), respectively. (W1−W4: λ1−λ4.)

Fig. 8. Receiver sensitivity variation among different fiber cores and wavelengths. (W1−W4: λ1−λ4.)