Broadband sum-frequency generation as an efficient two-photon detector for optical tomography

Avi Pe'er*, Yaron Bromberg, Barak Dayan, Yaron Silberberg, Asher A. Friesem

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


We describe a novel non-linear detection method for optical tomography that does not rely on detection of interference fringes and is free of optical background. The method exploits temporally coherent broadband illumination such as ultrashort pulses, and a non-linear two-photon detection process such as sum-frequency generation (SFG). At the detection stage, the reference beam and the sample beam are mixed in a thick non-linear crystal, and only the mixing term, which is free of optical background, is detected. Consequently, the noise limitations posed by the background in standard OCT (excess and shot noise), do not exist here. Due to the non-linearity, the signal to noise ratio scales more favorably with the optical power compared to standard OCT, yielding an inherent improvement for high speed tomographic scans. Careful design of phase matching in the crystal enables non-linear mixing which is both highly efficient and broadband, yielding both high sensitivity and high depth resolution.

Original languageAmerican English
Pages (from-to)8760-8769
Number of pages10
JournalOptics Express
Issue number14
StatePublished - 9 Jul 2007
Externally publishedYes


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