A novel MWP proposal for low-coherence interferometry applications

In this paper, by means of a well-established parallelism between MWP and LCI, a novel MWP-LCI technique is proposed and experimentally evaluated. This technique is based on the slicing of a broadband source which is transmitted through a dispersive element. The optical path differences (OPD) under test modifies the electrical transfer function of the MWP-LCI subsystem through a interferometric structure. The OPD range is increased due to the right allocation of the interferometric structure and extended close to zero for removing the basedband component due to the avoidance of the Carrier Suppression Effect (CSE) and the incorporation of a balanced detection, respectively. In this sense, an OPD range of more than 1.4 cm has been experimentally achieved. In the whole range, a considerable improvement of sensitivity has been achieved in comparison to previous contributions. For low OPD values, the improvement is around 6 dB, but more importantly, for high OPD values, a sensitivity improvement larger than 20 dB is achieved. 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.