We present, to the best of our knowledge, the first implementation of full-field quantum optical coherence tomography (FF-QOCT). In our system, we are able to obtain full three-dimensional (3D) information about the internal structure of a sample under study by relying on transversely resolved Hong–Ou–Mandel (HOM) interferometry with the help of an intensified CCD (ICCD) camera. Our system requires a single axial scan, obtaining full-field transverse single-photon intensity in coincidence with the detection of the sibling photon for each value of the signal-idler temporal delay. We believe that this capability constitutes a significant step forward toward the implementation of QOCT as a practical biomedical imaging technique.
We explore three different mechanisms designed to controllably tune the joint spectrum of photon pairs produced by the spontaneous four-wave mixing (SFWM) process in optical fibres. The first of these is fibre tapering, which exploits the modified optical dispersion resulting from reducing the core radius. We have presented a theory of SFWM for tapered fibres, as well as experimental results for the SFWM coincidence spectra as a function of the reduction in core radius due to tapering. The other two techniques that we have explored are temperature variation and application of longitudinal stress. While the maximum spectral shift observed with these two techniques is smaller than for fibre tapering, they are considerably simpler to implement and have the important advantage that they are based on the use of a single, suitably controlled, fibre specimen.
Quantum-optical coherence tomography (QOCT) is an optical sectioning modality based on the quantum interference of photon pairs [Nasr et al., Phys. Rev. Lett. 91, 083601 (2003)], obtained from a spontaneous parametric downconversion (SPDC) source. The promise of QOCT derives from two quantumconferred advantages when compared to equivalent classical optical coherence tomography (OCT) systems: a factor of 2 axial resolution enhancement, as well as dispersion cancellation. Despite its promise, the technique is far from being competitive with current OCT devices due to the long required acquisition times, derived from the low photon-pair emission rates. In this work, we on the one hand demonstrate a quantum optical coherence microscopy (QOCM) technique that is designed to overcome some of the limitations of previous QOCT implementations, and on the other hand test it on representative samples, including glass layers with manufactured transverse patterns and metal-coated biological specimens. In an effort to maintain as large a flux as possible, we use a collinear SPDC source, so that the entire emitted photon pair flux may contribute to the measurements, together with a multi-mode detection design. Consistent with the collinear design, we employ a Michelson interferometer with the sample placed as end-mirror in one of the interferometer arms, instead of the more typical Hong-Ou-Mandel used in QOCT implementations. In order to probe biological samples we transition from a Michelson to a Linnik interferometer by placing a microscope objective in the sample arm. In our setup, while the idler photon is collected with a multi-mode fiber, the signal photon is detected by an ICCD camera, leading to full-field transverse reconstruction through a single axial acquisition sequence. Interestingly, our setup permits concurrent OCT and QOCT trace acquisition, the former with greater counts and the latter with the benefit of quantum-conferred advantages. We 1
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.