Development of an ultrastable fiber optic frequency distribution system using an optical delay control module

An ultrastable fiber optic frequency distribution system is described. The ultrastable phase stability is achieved by configuring a closed phase-locke d loop with a single-mode optical fiber transmission line in which two opti cal carrier signals with different wavelengths are transmitted as a forward and a backward signal, and installing an optical delay control module whic h has no differential dispersion effect between the two optical carrier wav es and induces no electrical noise. A phase stabilized optical fiber (PSOF) is used for the signal transmission line. The stabilities of this system are 7.5 x 10(-17) and 1.1 x 10-17 in Allan S tandard Deviation (ASD) at 1000 and 10 000 s averaging time, respectively, while the environmental temperature of the PSOF cable varies as much as the range of 10 degrees C and the rate of 10 degrees C/12 h.