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 re...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-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)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 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.展开更多
We propose a method for optimizing the phase stability of microwave signal transmission over long distances.First,the design of the photon link was modified to reduce the radio frequency(RF)signal’s baseline noise an...We propose a method for optimizing the phase stability of microwave signal transmission over long distances.First,the design of the photon link was modified to reduce the radio frequency(RF)signal’s baseline noise and increase power.Second,a low-noise driver circuit was developed for a two-section distributed feedback(DFB)laser designed using reconstruction equivalent chirp(REC)technology to create an ultra-stable laser,and its performance was characterized through linewidth data.Test results indicate that the DFB laser achieved narrower linewidth,improving system phase stability.When an injection current(30 mA)is applied to the reflection section of the two-section DFB laser,the laser linewidth will be narrower(1.38 MHz),further enhancing the system’s phase transmission stability.At a 1 Hz offset frequency,a residual phase noise of-88.65 dBc/Hz is obtained.The short-term stability with an averaging time of 1 s is 1.60×10^(-14),and the long-term stability over a testing time of 60,000 s is 3.41×10^(-18).Even after incorporating temperature variations,the long-term stability reaches 8.37×10^(-18) at 22 h.展开更多
基金supported by the National Key R&D Program of China(No.2020YFB2205804)the National Natural Science Foundation of China(Nos.62273355,61975075,61975076,and 62004094)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20200334)the Jiangsu Science and Technology Project(No.BE2017003-2)。
文摘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-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)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 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.
基金This work was supported by the National Key R&D Program of China(No.2020YFB2205804)the National Natural Science Foundation of China(Nos.62273355,62374092,61975075,61975076,and 62004094).
文摘We propose a method for optimizing the phase stability of microwave signal transmission over long distances.First,the design of the photon link was modified to reduce the radio frequency(RF)signal’s baseline noise and increase power.Second,a low-noise driver circuit was developed for a two-section distributed feedback(DFB)laser designed using reconstruction equivalent chirp(REC)technology to create an ultra-stable laser,and its performance was characterized through linewidth data.Test results indicate that the DFB laser achieved narrower linewidth,improving system phase stability.When an injection current(30 mA)is applied to the reflection section of the two-section DFB laser,the laser linewidth will be narrower(1.38 MHz),further enhancing the system’s phase transmission stability.At a 1 Hz offset frequency,a residual phase noise of-88.65 dBc/Hz is obtained.The short-term stability with an averaging time of 1 s is 1.60×10^(-14),and the long-term stability over a testing time of 60,000 s is 3.41×10^(-18).Even after incorporating temperature variations,the long-term stability reaches 8.37×10^(-18) at 22 h.
