Harmonic optical tomography of nonlinear structures

Chenfei Hu, Jeffrey J. Field, Varun Kelkar, Benny Chiang, Keith Wernsing, Kimani C. Toussaint, Randy A. Bartels, Gabriel Popescu

Research output: Contribution to journalArticlepeer-review


Second-harmonic generation microscopy is a valuable label-free modality for imaging non-centrosymmetric structures and has important biomedical applications from live-cell imaging to cancer diagnosis. Conventional second-harmonic generation microscopy measures intensity signals that originate from tightly focused laser beams, preventing researchers from solving the scattering inverse problem for second-order nonlinear materials. Here, we present harmonic optical tomography (HOT) as a novel modality for imaging microscopic, nonlinear and inhomogeneous objects. The HOT principle of operation relies on interferometrically measuring the complex harmonic field and using a scattering inverse model to reconstruct the three-dimensional distribution of harmonophores. HOT enables strong axial sectioning via the momentum conservation of spatially and temporally broadband fields. We illustrate the HOT operation with experiments and reconstructions on a beta-barium borate crystal and various biological specimens. Although our results involve second-order nonlinear materials, we show that this approach applies to any coherent nonlinear process.

Original languageEnglish (US)
Pages (from-to)564-569
Number of pages6
JournalNature Photonics
Issue number9
StatePublished - Sep 1 2020

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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