Measurement of the temporal coherence in broadband sources using the radio-frequency transfer function of a dispersive system

We present a noninterferometric method for direct and complete characterization of the degree of first-order temporal coherence γ(τ) of low-coherence broadband sources both in amplitude and phase. The method is based on measuring the radio-frequency transfer function HRF(f) of amplitude-modulated partially coherent guided waves in a system with first-order dispersion. Experimental data for sources based on amplitude-modulated amplified spontaneous emission in the 1.55 μm band having spectral widths up to 30 nm and subsequently dispersed in a 12.77 km standard single-mode fiber coil provide complete characterization of the temporal coherence with 6.5 fs resolution and a dynamic range exceeding 20 dB.