Simple-Design Low-Noise NLTL-Based Frequency Synthesizers for a CPT Cs Clock

This paper presents simple-architecture low-noise frequency synthesis chains generating a 9-GHz signal. These devices are based on the use of a nonlinear transmission line (NLTL) used as a comb generator. The residual phase noise spectra of the key components are reported. The residual phase noise performance of the chains at 9 GHz is measured to be less than -80 dBrad²/Hz at 1-Hz offset frequency. The measured fractional frequency stability of the chains is 1 times 10^-14 at 1 s and better than 4 times 10^-17 at one day. The contributions of these chains to phase lock two extended cavity diode lasers (ECDLs) involved in a coherent-population-trapping (CPT) Cs clock experiment are evaluated and measured.