Phase coherent nonlinear spectroscopy and sources

  • Herman Offerhaus - Chair
  • Philip Chimento - Former member
  • Martin Jurna - Former member
  • Erik Garbacik - Former member
  • Andrew Fussell - Former member
  • Birthe Kann - Former member
  • Alyssa Stephenson - Former member

Phase coherent nonlinear spectroscopy and sources

Coherent Anti-Stokes Raman Scattering (CARS) is a complicated but promising phase coherent nonlinear technique for label-free detection and chemical selectivity of large molecules. The resonant enhancement of the CARS process makes it faster than Raman and, compared to IR spectroscopy, the short wavelengths involved, ensure a higher spatial resolution. Application in industry has been limited due to the complexity of the required systems and the low yield of the highly nonlinear interaction. To make this technique widely applicable, sources must be developed that provide turn-key operation and reasonable signal levels at the relevant wavelengths. An Optical Parametric Oscillator (OPO) pumped by a 532nm picosecond laser provides tunable output in the proper wavelength region with an appropriate bandwidth for CARS spectroscopy and microscopy at the characteristic CH stretching vibration.

In this research we have several goals:

  • Improvement of the sensitivity limit of CARS spectroscopy and microscopy
  • Improvement of the selectivity of the signal (rejection of non-resonant signal)
  • Application to biological relevant questions

In the image below a Sebaceous Gland can be seen inside a rat's ear at a typical depth of 50 μm at the lipid vibrational stretch frequency of 2845 cm-1.