Dr Sven Ramelow visited the AOG and the School of Physical Sciences on Wednesday, March 4th, also delivering a talk in the School's colloquia, titled "Microscopy, Spectroscopy and OCT with undetected photons". Dr Ramelow, from the Institute of Physics at Humboldt University Berlin is an expert in quantum imaging and quantum spectroscopy.
Abstract
Mid-infrared light scatters much less than shorter wavelengths, allowing greatly enhanced penetration depths for optical imaging techniques such as optical coherence tomography (OCT). However, both detection and broadband sources in the mid-IR are technologically challenging. Interfering entangled photons in a nonlinear interferometer enables sensing with undetected photons making mid-IR detectors obsolete. Here we implement mid-infrared frequency-domain OCT based on ultra-broadband entangled photon pairs and demonstrate 10 μm axial and 20 μm lateral resolution imaging of strongly scattering ceramic and paint samples. Achieving high SNR with 6 orders of magnitude less probe light than would be necessary with conventional mid-IR OCT and vastly reduced technical complexity this outperforms approaches with classical light.
Speaker Biography
Dr. Sven Ramelow is for more than 10 years involved in experimental research with single photons. After his studies of physics at Humboldt-University Berlin, he completed his PhD and first PostDoc in Prof. Anton Zeilinger’s group at the University of Vienna. Here he dedicated his research to a number of fundamental quantum experiments as well as application-motivated topics like quantum communication and quantum imaging. During his second PostDoc at Cornell University, USA in Prof. Alex Gaeta’s group he extended his expertise in integrated quantum optics and quantum frequency conversion. Since 2017 Dr. Ramelow is leading an Emmy-Noether research group at Humboldt-University Berlin experimentally working on integrated optics, quantum frequency conversion and SPDC-based imaging, spectroscopy and OCT with undetected mid-IR photons.
Recent publication highlights
- Inna Kwiatkovsky, Helen Chrzanowski, Ellen G. Avery, Hendrik Bartolomaeus, Sven Ramelow “Microscopy with undetected photons in the mid-infrared”, arXiv:2002.05960
- Joshi, A. Farsi, S. Clemmen, S. Ramelow, A. L. Gaeta, “Frequency Multiplexing for Quasi-Deterministic Heralded Single-Photon Sources“, Nature Comm. 9, 847 (2018)
- Clemmen, A. Farsi, S. Ramelow, A. L. Gaeta, “Ramsey interference with single photons“, Phys. Rev. Lett. 117, 223601 (2016)
- Baretto Lemos, V. Borish, G. D. Cole, S. Ramelow, R. Lapkiewicz, A. Zeilinger, “Quantum Imaging with Undetected Photons”, Nature 512, 409 (2014)
