Abstract
In this study, we proposed a photonic microwave interferometry which aims to extend Non-Ambiguity Range (NAR) of the typical interferometer. A 6 GHz microwave signal (Λ = 5 cm) was generated by a signal generator and was carried by light through direct modulation to the semiconductor laser. The microwave carried by light, so-called photonic microwave, was used as the optical source of the interferometer. After the testing signal returning from the target and interfering with the reference signal, the phase of the microwave was directly extracted and the displacement of the target was resolved. We also tested two different phase extraction methods, which are lock-in method and quadrature detection method. The phase stability under different experimental setup and the relation between signal strength and phase are also discussed. By using the microwave as the actual detecting signal, we extend the NAR to 2.5 cm. Since the microwave signal has narrow linewidth and stable frequency, 12 μm resolution of displacement measurement (standard deviation of 5 measurements) is achieved, which is equivalent to Λ/4000.