搭建了一套光纤相位噪声抑制系统。通过环外自拍频,得到噪声本底的秒级频率稳定度为6.8×10~(-18),2000s平均时间后达到2.3×10~(-19)。利用该系统可实现窄线宽激光频率在1.6km实际光纤链路中的传输,传输后环外自拍频信号的秒级频率稳定度可达1.2×10~(-17)。基于连接两个实验室的808m实际光纤链路,将此系统应用于1.5μm超稳激光的比对,通过拍频测量得到激光线宽为(0.54±0.15)Hz,秒级频率稳定度为1.2×10~(-15)。 Set up a fiber optic phase noise suppression system. The second-order frequency stability of the noise floor is 6.8 × 10 ~ (-18) by out-of-loop self-beat frequency and 2.3 × 10 ~ (-19) after 2000s average time. The system can realize the transmission of narrow linewidth laser frequency in the actual optical fiber link of 1.6km. After the transmission, the second-level frequency stability of the loop self-beat signal can reach 1.2 × 10 ~ (-17). Based on the 808m actual optical fiber links connecting the two laboratories, the system was applied to the comparison of 1.5μm ultrastable laser. The laser linewidth was (0.54 ± 0.15) Hz and the second-order frequency stability was 1.2 × 10 ~ (-15).