Comparison Of Two Different Wavelength Narrow Linewidth Laser Systems Via Long Distance Of Fiber Link

With the rapid development of metrological science,optical atomic clock has the properties of high stability and accuracy.It has potential to replace the cesium atomic fountain clock to become a new generation of time and frequency standard.The signal of optical atomic clock will has an important application in time generation and maintenance,relativistic verification,Global Position System?GPS?and geodesy.Most applications require long-distance transmission of signal of optical atomic clock.Based on the current status of the laboratory.We need do some research on comparison of two different wavelength ultra-stable narrow-linewidth lasers which is located in different laboratories to verify the level of the ultra-stable laser as the oscillator of the optical atomic clock.There are two kinds of work in the study.For one thing,building a set of dynamic noise suppression system which can be used for long-distance transmission of ultra-stable laser.For another,comparison of two ultra-stable laser via frequency comb.This paper introduced the main work based on the above experimental requirements:1.A set of dynamic noise suppression system for long-distance transmission of ultra-stable laser is studied and developed.The principle of system based on Michelson interferometer in which the fiber link act as measuring arm.The frequency-stabilized laser is transmitted through the fiber to the far end,part of light re-enter the fiber link through reflector.The path of light travels through the fiber link could be thought same because of interval is too short?length of optical fiber/velocity of laser in fiber?.Therefore,the noise was introduced in the optical fiber could be thought same.The noise information could be obtained through comparing the measuring arm and reference arm.Choosing the acousto-optic modulator as the implementation of the device and the PID servo control system is established to compensate for the noise of the fiber to make the laser frequency of remote output stable.Then,the loss model of the optical fiber frequency transmission system is analyzed and the loss of the components of the system is calculated.The whole system is established by using the optical components,the optical fiber components,the driving circuit and the control circuit.And optimizing the parameters according to the actual situation of the experiment.In the paper,we firstly realize the phase noise suppression of narrow linewidth laser in a 50-km-long spooled fiber.The instability of transfer reaches2.3×10^-17?1s?and the relative broadening linewidth is suppressed to 1.67mHz.Then we realize the phase noise suppression of narrow linewidth laser in a 100-km-long spooled fiber by linking two series of 50-km-long spooled fibers.The instability of transfer reaches 5.72×10^-17?1s?and the relative broadening linewidth is suppressed to 10mHz.Finally,we realize the phase noise suppression of narrow linewidth laser in a 108-km-long telecommunication fiber link.The instability of transfer reaches1.59×10^-16?1s?.The results meet the requirement of the ultra-stable laser transmission.2.Realizing the comparison of two different wavelength narrow linewidth laser.The homemade 698nm short cavity?10cm?narrow linewidth laser was used as the reference of frequency comb.Then,locking the femtosecond optical frequency comb.Next,narrow linewidth laser signal of the commercial 1542nm ultra-stable laser system was transmitted to the Hepingli campus to finish the comparison with homemade 698nm short cavity narrow linewidth laser.Finally,realizing the comparison between 1542nm narrow linewidth laser and 698nm long cavity narrow linewidth laser.So,The current level of the 698nm long cavity narrow linewidth laser is verified.In the paper,we firstly realized the comparison between 1542nm narrow linewidth laser and 698nm short cavity narrow linewidth laser.The instability of beat note could reach 1.6×10^-15?1s?.According to the previous results,we thought the whole system is normal.Therefore,we realized the comparison between 1542nm narrow linewidth laser and 698nm long cavity narrow linewidth laser.The instability of beat note could reach 2.8×10^-15?1s?,the result shows the current level which the698nm long cavity narrow linewidth laser could reach.