STATE OF THE ART FIBER OPTICS FOR REFERENCE FREQUENCY DISTRIBUTION OVER SHORT DISTANCES

George Lutes, Lori Primas

Abstract:	We have characterized a number of recently developed fiber optic components that hold the promise of unprecedented stability for passively stabilized frequency distribution links. These components include a fiber optic transmitter, an optical isolator and a new type of fiber optic cable. A novel laser transmitter exhibits extremely low sensitivity to intensity and polarization changes of reflected light due to cable ?exure. This virtually eliminates one of the shortcomings in previous laser transmitters. A high isolation, low loss optical isolator has been developed which also virtually eliminates laser sensitivity to changes in intensity and polarization of reflected light. A newly developed fiber has been tested. This fiber has a thermal coefficient of less than 0.5 ppm/°C, nearly 20 times lower than the best coaxial hardline cable and 10 times lower than any previous fiber optic cable. The use of this fiber in frequency distribution systems will greatly enhance the stability. These and other components are highly suitable for distribution systems with short extent, such as within a building. A test was performed to demonstrate the insensitivity to cable flexure when these new components are used in a fiber optic link. The standard loose tube fiber optic cable was installed between the control room and the cone of an antenna in a NASA/JPL Deep Space Station. The round trip cable length was 850 meter. Delay variations in the fiber optic cable were measured and compared to delay variations in an adjacent coaxial cable. Phase delay was monitored while antenna movement flexed the cables. The measured stability of the fiber optic cable was found to be substantially superior to that of the coaxial cable. In this paper, we will present results of our tests and provide the design for a stable distribution link, together with the projection of the stabilities achievable with the present state-of-the-art.
Published in:	Proceedings of the 20th Annual Precise Time and Time Interval Systems and Applications Meeting November 29 - 1, 1988 Sheraton Premiere Hotel Vienna, Virginia
Pages:	13 - 22
Cite this article:	Lutes, George, Primas, Lori, "STATE OF THE ART FIBER OPTICS FOR REFERENCE FREQUENCY DISTRIBUTION OVER SHORT DISTANCES," Proceedings of the 20th Annual Precise Time and Time Interval Systems and Applications Meeting, Vienna, Virginia, November 1988, pp. 13-22.
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