Low-coherence reflectometry based on DFWM in a thin liquid layer

Academic Article


  • We describe a coherence filtering technique based on degenerate four wave mixing (DFWM) in a thin nonlinear optical material. In contrast to previous works which used ultra-short laser pulses, we performed low-coherence filtering techniques through scattering media with broad-spectrum nanosecond pulses. In our first 'proof of principle' experiments we used a 100 micrometer thick layer of dye solution as a nonlinear optical material and investigated a one dimensional case for depth-resolved measurements through a scattering media consisting of a highly scattering suspension of dielectric microspheres in water. We also describe a technique to obtain instantaneous cross-sectional images (which can be depth scanned to obtain the third dimension) performed with a low-coherence nanosecond laser source on a liquid crystal doped with an infrared dye. Experimental results were obtained with room temperature LiF:F 2- and LiF:F 2+ color center lasers, and a Q-switched alexandrite laser. This technique can be used to provide instantaneous, single-shot, two-dimensional images of the internal structure of materials versus depth.
  • Published In

    Author List

  • Fleurov VB; Lawson CM; Brown D; Dergachev AY; Mirov SB; Lindquist RG
  • Start Page

  • 126
  • End Page

  • 134
  • Volume

  • 2853