Photoacoustically guided wavefront shaping for enhanced optical focusing in scattering media

Puxiang Lai, Lidai Wang, Jian Wei Tay, Lihong V. Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

194 Citations (Scopus)


Non-invasively focusing light into strongly scattering media, such as biological tissue, is highly desirable but challenging. Recently, ultrasonically guided wavefront-shaping technologies have been developed to address this limitation. So far, the focusing resolution of most implementations has been limited by acoustic diffraction. Here, we introduce nonlinear photoacoustically guided wavefront shaping (PAWS), which achieves optical diffraction-limited focusing in scattering media. We develop an efficient dual-pulse excitation approach to generate strong nonlinear photoacoustic signals based on the Grueneisen relaxation effect. These nonlinear photoacoustic signals are used as feedback to guide iterative wavefront optimization. As a result, light is effectively focused to a single optical speckle grain on the scale of 5-7Î 1/4m, which is ~10 times smaller than the acoustic focus, with an enhancement factor of ~6,000 in peak fluence. This technology has the potential to benefit many applications that require a highly confined strong optical focus in tissue.
Original languageEnglish
Pages (from-to)126-132
Number of pages7
JournalNature Photonics
Issue number2
Publication statusPublished - 1 Jan 2015
Externally publishedYes

ASJC Scopus subject areas

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

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