Fig. 1. (Color online) Assembly schematic of proposed DML.

Fig. 2. (Color online) (a) Measured optical spectrum of DML. (b) Frequency response of DML. (c) Measured P–I curve of DML.

Fig. 3. (Color online) Experimental setup of single wavelength PAM-4 signal transmission.

Fig. 4. (Color online) BER performances versus ROP for different distance.

Fig. 5. (Color online) BER versus FFE tap number.

Fig. 6. (Color online) BER performance with FFE and without FFE versus ROP for 35 km.

Fig. 7. (Color online) The eye diagram performance for different distance.