Cascaded optical frequency transfer over 500-km fiber link using regenerative amplifier

Deng Xue^{1, 2, 3}, Jiao Dong-Dong^{1, 2, 3}, Liu Jie^{1, 3}, Zang Qi^{1, 2, 3}, Zhang Xiang^{1, 2, 3}, Wang Dan^{1, 3}, Gao Jing^{1, 2, 3}, Dong Rui-Fang^{1, 2, 3}, Liu Tao^{1, 3, †}, Zhang Shou-Gang^{1, 2, 3}

Transfer instability versus averaging time for Allan deviation of unstabilized 300-km link (black line), stabilized 300-km link (red line), stabilized 200-km link (blue line), stabilized 500-km link (green line), and modified Allan deviation of stabilized 500 km (orange line) as well.