Atomic, Molecular, and Optical Physics Seminar
CARS using Femtosecond Chirped Pulses: Control and Applications
Department of Physics and Engineering Physics
Stevens Institute of Technology (Hoboken, NJ)
Coherent anti-Stokes Raman scattering (CARS) is a four wave mixing process utilizing ultrafast laser pulses to generate strong, molecular-specific signals. Quantum control methods, when applied to CARS spectroscopy and microscopy, provide high molecular specificity by selective excitation of predetermined Raman transitions via ultrafast laser pulse manipulation. We propose a new method for vibrational mode selective excitation in CARS based on chirped pulse adiabatic passage . This method may be used in impulsive and non-impulsive regime of light-matter interaction. We discuss the liquid phase aspects of the control technique arising from the molecular interaction with the solvent environment. We study the energy and phase relaxation as factors of the optical polarization decay and show that in strong fields the dynamics of induced polarization is dependent on phase relaxation, and to less extent on vibrational energy relaxation for characteristic times close to pulse duration. Chirped pulse adiabatic control of vibrational dynamics in CARS is expected to advance the development of novel imaging techniques.  S.A. Malinovskaya, "Mode selective excitation using ultrafast chirped laser pulses", Phys. Rev. A 73, 033416 (2006); S.A. Malinovskaya, V.S. Malinovsky, "Chirped pulse adiabatic control in CARS for imaging of biological structure and dynamics", Optics Lett. 32, 76025 (2007).
Monday, April 9, 2007
Gant Science Complex