Division of Time and Frequency




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General Information:

Address: No.18,Bei San Huan
Dong Lu,Chaoyang
Dist,Beijing,P.R.China, 100013



Director's Greeting


Welcome to the Division of Time and Frequency. The TF division maintains the national primary standard for frequency and time interval for China, and provides dissemination of legal time and related measurement services to Chinese customers. In the recent several years, the TF division has received three National Prizes for Progress in Science and Technology. Our on-going research projects and future directions include mainly: fountain clock based microwave frequency standard, optical clock, frequency comb and related technologies, frequency and time transfer through fiber & other advanced time and frequency transfer technologies.


Fang Zhanjun, Director of Division

Dr. Fang Zhanjun is also the leader of the strontium optical lattice clock research group. The Strontium optical lattice clock project in NIM started in 2006. Dr. Zhanjun Fang and his colleagues designed their Strontium cooling and trapping vacuum system, which includes an effusive oven, a Zeeman slower and a Magneto-Optical Trap (MOT). Until now, they have realized the first stage laser cooling 461nm blue MOT,the second stage laser cooling 689nm red MOT, the 813nm magic wavelength optical lattice loading and trapping. In the October of 2012, the group obtained their first side-band resolved spectrum of the clock transition of 87Sr.           


From 2002 to 2006, Dr. Fang  was the leader of the femtosecond optical frequency comb research group. He and his colleagues built NIM’s first Ti:Sapphire optical frequency comb in 2006. For the first time in China, using their frequency comb, the group measured the absolute optical frequency of the Iodine stabilized 633nm He-Ne laser, which still severs as the national primary standard for wavelength. This work was awarded the 2nd prize of National Sci. and Tech. Progress Award in 2009.


From 1990 to 1995, Dr. Fang participated in several research projects aiming at the establishment of measurement standards for optical fiber parameters, for example the standard apparatus for measuring the refractive index profile of optical fibers, the fiber length and loss standards for calibrating optical time domain reflectometer (OTDR), etc.