Phase-sensitive light : coherence theory and applications to optical imaging

Abstract

Spontaneous parametric downconversion (SPDC) can produce pairs of entangled photons, i.e., a stream of biphotons. SPDC has been utilized in a number of optical imaging applications, such as optical coherence tomography, ghost imaging, holography and lithography, to obtain performance that cannot be realized with standard optical sources. However, a debate continues as to whether the improved imaging characteristics of such systems should be attributed to the entanglement property of the photon pairs. This thesis sets out to unify--and generalize--classical and quantum imaging within the framework of Gaussian-state light fields, which encompasses thermal light--the source used in conventional imagers--and biphoton-state light as special instances. Within this framework, we are able to provide a complete understanding of the boundary between classical and quantum behavior in optical coherence tomography (OCT), ghost imaging and two-photon imaging. Furthermore, we show that almost all characteristics of biphoton-state imagers are due to phase-sensitive cross correlations, and hence are obtainable with classical phase-sensitive sources.