Novel approach for Low Coherence Interferometry based on a microwave photonic architecture

Microwave Photonics (MWP) is a discipline which offers new opportunities to Low-Coherence Interferometry (LCI). In this paper, a novel MWP-LCI technique is presented by means of a well-established parallelism between both worlds, MWP and LCI. This technique is based on the slicing of a broadband source which is transmitted through a dispersive element. The optical path differences under test modify the electrical transfer function of the MWP-LCI subsystem through a interferometric structure. In this case, the location of the interferometric structure is key to improve considerably the limitations of previous configurations according to key LCI parameters such penetration depth and resolution. The advantages of this new technique have been experimentally demonstrated by means of the measurement of the system electrical function transfer. On the one hand, the strategic allocation of the interferometric structure extends the penetration depth up to 2 cm which supposes at least more than a factor of 3 compared to previous contributions. This is mainly due to the Carrier Suppression Effect (CSE) in double-sideband modulated MWP systems is avoided. On the other hand, it is also demonstrated that the proposed scheme maintains the resolution through the complete measurement range. These key parameters only depends on the operation bandwidth of the RF and electrooptical components.