Microwave frequency measurement (MFM) is of great importance in civil and defense systems. Traditional implementations based on high-speed electronic components can provide a measurement range from a few gigahertz to a few hundred gigahertz which is limited due to the electronic bottleneck. And they usually have bulky size and sensitive to electromagneticinterference. In recent years, photonic-assisted MFM has attracted great attentions for the advantages of low loss, small size, real-time measurement and large frequency range.
Prof. Junqiang Sun and Phd. Danqi Feng of Wuhan National Laboratory implement MFM utilizing pump-induced nonlinear birefringent effect in the highly non-linear fiber (HNLF). By adjusting the operational parameters of the optical pump signal, a complementary polarization domain interferometer pair with tunable free spectral range is established in HNLF. By monitoring the signal light powers at orthogonal states of polarization, the microwave frequency can be evaluated. A frequency measurement range of 2.5-30 GHz except 16-17.5 GHz with a measurement error within 0.5 GHz is achieved.
On June, 29, 2015, this work “Photonic approach for microwave frequency measurement with adjustable measurement range and resolution using birefringence effect in highly non-linear fiber” was published on Optics Express of OSA (Vol. 23, Issue 13, pp. 17613-17621 2015). This work is partially supported National Natural Science Foundation of China under Grant 61178002 and Research Fund for the Doctoral Program of High Education of China under Grant 20120142130004.