Two-photon fluorescence correlation spectroscopy through a dual-clad optical fiber

Yu Chung Chang, Jing Yong Ye, Thommey Thomas, Yi Chen, James R. Baker, Theodore B. Norris

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


We report on the utilization of a dual-clad optical fiber for two-photon excited fluorescence correlation spectroscopy (FCS). High excitation efficiency is obtained by sending prechirped ultrafast pulses through the single-mode core of the fiber, while the fluorescence collection efficiency is enhanced because of the larger numerical aperture of the inner cladding. We show that the utilization of a dual-clad fiber is critical for ultrasensitive two-photon fluorescence detection. Our system has the ability to detect fluorescent nanospheres as small as 12 nm in radius. Quantum dots of radius 7 nm are also measured and show excellent signal to noise ratio. The particle sizes obtained from the fiber FCS system were confirmed by measurements using a commercial dynamic light scattering (DLS) system.

Original languageEnglish
Pages (from-to)12640-12649
Number of pages10
JournalOptics Express
Issue number17
Publication statusPublished - 2008 Aug 18

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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