Figure 1 illustrates the bidirectional ROF transport system based on the SBS effect and injection-locked DFB laser technology. A tunable laser (TL) and a DFB laser are used as a master laser and a slave laser, respectively. The wavelength of the DFB laser is 1546.58 nm. The main parts of a transmitter include a TL source, a microwave signal generator, an RF power amplifier, an RF power splitter, a mixer, a semiconductor optical amplifier (SOA), and a Mach–Zehnder modulator (MZM). A microwave signal is generated at 10.8 GHz by the microwave signal generator then fed into the RF power splitter to split into two copies. One copy of the RF signal passes through the RF power amplifier to increase signal power then is coupled into the mixer. The other copy is supplied to the other RF power amplifier to increase signal power as a local oscillation (LO) signal of the receiver. The nonreturn-to-zero (NRZ) pseudorandom bit sequence (PRBS) length of is mixed with a 10.8 GHz microwave carrier to generate an up-conversion data signal, and the resulting microwave data signal is supplied to the MZM. The TL output signal launches into a 10:90 coupler. Afterward, 90% light is modulated by the microwave data signal at 10.8 GHz via the MZM with an insertion loss of approximately 7 dB. The remaining 10% light is amplified by the SOA and thus acts as a feedback light for the enhanced OSSB modulation. The modulated signal is launched into a 25-km SMF then subsequently interacts with the feedback light from the optical circulator. After the 25-km SMF transmission, an output signal is generated by using an injection-locked technology via a DFB laser to double enhance the OSSB modulation. The output OSSB signal enters an erbium-doped fiber amplifier (EDFA) and amplifies for another 25-km SMF transmission. After fiber transmission, the optical signal enters the EDFA and amplifies, then is separated into two parts by an optical interleaver (IL). In the even channel, the optical spectrum of the optical signal is obtained by using an optical spectrum analyzer (OSA). A photodetector (PD) transforms the optical signal to an electrical signal and performs down-conversion to base band via the mixer for a bit error rate (BER) test. In the odd channel, the optical signal is reused as an uplink light carrier. A NRZ PRBS signal is mixed with 8 GHz to generate an uplink data signal and is modulated by the phase modulator. The modulated light signal enters the EDFA and amplifies to achieve the 25-km SMF transmission. The uplink light signal is subsequently fed into a delay interferometer (DI) to transfer the PM signal into an intensity-modulated signal. Afterward, the optical signal enters the receiver to perform O/E conversion for the BER test.