Real-time Microwave Photonic technique for Low-Coherence Interferometry applications

Low-Coherence Interferometry (LCI) is a highly relevant optical measurement technique used in a wide variety of applications from sensing to medical imaging among others due to its non-invasive performance with high axial precision. In this work, a novel structure is proposed with the application of Microwave Photonics (MWP) as key enabling technology for real-time LCI applications. The proposed MWP-LCI technique permits the measurement of the optical path difference in the time domain by processing the incoherent optical signal modulated by an electrical RF pulse. The possibility of retrieving the interferogram information by an oscilloscope is experimentally demonstrated achieving a scanning speed of tens of MHz required by real-time LCI applications with moderate signal-to-noise ratio (SNR). We have achieved an acquisition rate of 20 MHz increasing in more than 5 magnitude orders compared to previous techniques operating in frequency domain with similar SNR performance.