AbstractBased on the physical model of a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in radio over fiber (RoF) links, the distributions of carrier density, signal photon density, and amplified spontaneous emission photon density are demonstrated. One of limits in the use of RSOA is the lower link gain when compared with a distributed feedback laser modulator. To improve the link gain of RSOA modulator in RoF links, we investigate the characteristics of the RSOA modulator with a dual‐electrode configuration. Therefore, there are two kinds of configuration: Case I, the modulating signal is injected at the input&output facet of the ROSA modulator; Case II, the modulating signal is injected at the mirror facet. The link gain of the RSOA modulator can be improved with the dual‐electrode configuration under proper biases. The link gain improvement of about 6 dB is obtained with the Case II configuration under proper bias currents.