半导体光放大器（SOA）能稳定产生高消光比的窄脉冲光，在光纤传感领域得到了广泛应用，但目前大多方案仅采用单向调制的SOA产生脉冲光。为了进一步提高脉冲光的消光比，基于SOA能双向工作的特点提出了一种双向窄脉冲光调制的SOA系统。使用光纤反射镜对SOA单向调制输出的脉冲光进行反射，使反射光重新返回到SOA进行第二次脉冲光调制。实验结果表明：相比单向调制，在低输入功率下，双向调制最大可获得6.18 dB的额外增益；对于输入峰值功率为6 dBm的脉冲光，双向吸收能使泄漏光强度进一步减弱30 dB以上，整体吸收率达到72 dB以上。

Semiconductor optical amplifier (SOA) can be used to generate narrow optical pulse with steady high extinction ratio and has been widely used in the field of optical fiber sensing. However, most of current schemes only employ SOA in unidirectional modulation for pulse generation. Based on the feature that SOA can work in both directions, this paper proposes a bidirectional narrow pulse modulation of SOA to further enhance the extinction ratio of optical pulse. A fiber optic mirror is used to reflect the optical pulse generated by unidirectional modulation back to the SOA for the second pulse modulation. The experimental results show that compared with unidirectional modulation, bidirectional modulation achieves a maximum extra gain of 6.18 dB at low input optical power. For pulsed light with an input peak power of 6 dBm, the bidirectional absorption can further weaken the leakage light intensity by more than 30 dB, and the overall absorption rate reaches more than 72 dB.