Elimination of the PMD related delay jitter in a fiber stretcher based ultra-stable microwave signal distribution system

We realize an ultra-stable microwave signal distribution system based on an optical phase-locked loop. The transmission delay jitter is accurately compensated with a piezoelectric fiber stretcher (PFS). For further eliminating the additional delay jitter originated from the polarization changes during the PFS stretching, we propose an orthogonal-polarized round-trip PFS structure. The transmission delay jitter of 24 GHz signals distributed to multiple remote ends using the proposed and the traditional PFS scheme are carefully compared and quantitively analyzed under various fiber types and lengths. With the proposed PFS structure, the relative delay jitter of two transmitted signals are decreased from 291.4 fs to merely 17.7 fs even via 200 m polarization maintaining fiber with considerable polarization mode dispersion, showing its remarkable superiority. This microwave signal distribution system can find its versatile applications in radio astronomy where multiple ultra-high relative stable microwave signals are highly desired in different locations.