Experimental Study Of Fiber Optical Frequency Transfer Based On Optical Amplifier Techniques

With the successful development of optical clock,its instability and uncertainty have reached the E-18 order of magnitude.High-precision time and frequency signal transmission is also facing a huge challenge,the traditional microwave-based time frequency transmission stability can only reach the E-16 magnitude,can not meet the high-precision light signal transmission requirements.The optical fiber can directly transmit the optical frequency signal,so that the light signal transmission possible.The use of optical fiber links for high-precision optical frequency signal transmission can not only achieve the accuracy of related applications,but also can use wide-area atomic clock to achieve large-scale cross-disciplinary research.In this paper,the long-distance transmission of high-precision optical frequency signals in optical fiber is introduced in detail based on optical fiber Doppler noise suppression technology and optical fiber relay amplification technology.Firstly,the principle of optical phase noise is introduced.By transmitting the transmitted optical signal in the fiber-optic link,the phase noise signal is obtained by the beat system,and then the link is compensated by the servo system to obtain the high-precision optical frequency signal.Secondly,in order to increase the transmission distance,the low noise bidirectional EDFA and the relay station system based on the one-way twostage EDFA are developed,and the two relay amplification modes are studied in detail from the principle and structure.In the experiment,bidirectional EDFA was used to achieve 3.8E-16/s in the laboratory 200 km transmission link,and reached the transmission stability of 2.8E-19 / 104 s after 10,000 seconds.In addition,the use of relay stations and bidirectional EDFA between Lintong and Xi'an one-way 56 km optical fiber construction of 224 km transmission link to achieve a high precision optical frequency signal transmission,transmission stability of 3.39E-16/s,10000 seconds to reach 8.36E-19.In the field communication cable of optical frequency transmission test,the bidirectional EDFA as a power compensation device in Xi'an-Xianyang between the provincial backbone of the telecommunications network to build a 210 km optical frequency signal transmission test link,the average amplifier gain 15 dB to prevent lasing.The additional phase noise of the fiber link under different conditions is measured and analyzed.At the same time,the optical frequency transmission stability of 1.51E-14 /s and over 5E-17 is obtained at 210 km field fiber link.Based on the test,the theoretical results of the thousands kilometers transmission are analyzed.The phase noise between different sites is tested by using the bidirectional EDFA as the power compensation device in the new Shanghai-Nanjing backbone fiber between Nanjing and Suzhou.According to the experimental and test results,noise suppression system,bidirectional EDFA and relay station can meet the high-precision optical frequency signal in the optical fiber in the long-distance transmission.Which provides support for high-precision optical signal transmission and comparison based on communication cable.