Synthesis of optical-coherence function and its applications in distributed and multiplexed optical sensing

We have proposed and demonstrated in recent years a unique technique to synthesize the optical-coherence function by manipulating the frequency and the phase of lightwave. Based upon this technique, the synthesis of optical coherence function (SOCF), various distributed photonic sensing and optical-information-processing applications have been developed. In this paper, the principle of SOCF is summarized. A series of functional optical-sensing systems, including fiber-optic reflectometries, distributed stress-location sensors, multiplexed fiber Bragg grating (FBG) sensors, are introduced. Fully distributed fiber-optic strain sensing systems by Brillouin frequency shift are highlighted, and a distributed sensor based on synthesized dynamic grating is also presented. Applications in two- or three-dimensional distributed measurements, such as optical tomography of scattering medium, are also reviewed.