Long-term ultrastable frequency dissemination via a 50-km spooled fiber link using a two-section DFB laser
The stable long-distance transmission of radio-frequency (RF) signals holds significant importance from various aspects, including the comparison of optical frequency standards, remote monitoring and control, scientific research and experiments, and RF spectrum management. We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber. The optical RF signal is generated using a two-section distributed feedback (DFB) laser for direct modulation based on the reconstruction equivalent chirp (REC) technique. The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of is achieved at 10-Hz offset frequency. We report a short-term stability of at an average time of 1 s and a long-term stability of at the measurement time of 62,000 s when applying current to the front section of the DFB laser. By applying power to both sections, the stability of the system improves to within a testing period of 56,737 s. Despite applying temperature variations to the transmission link, long-term stability of at 23.9 h can still be achieved.
Zhiqian Yin, Chuanbo Zhang, Shijian Guan, Xin Zhou, Yaguang Wang, Leilei Wang, Manhang Zheng, Yitong Liu, Yunshan Zhang, Xingbang Zhu, Tao Fang, Xiangfei Chen. Long-term ultrastable frequency dissemination via a 50-km spooled fiber link using a two-section DFB laser[J]. Chinese Optics Letters, 2024, 22(1): 013903.