  We present a new interferometric technique for measuring Coherent Anti-Stokes
Raman Scattering (CARS) and Second Harmonic Generation (SHG) signals.
Heterodyne detection is employed to increase the sensitivity in both CARS and
SHG signal detection, which can also be extended to different coherent
processes. The exploitation of the mentioned optical nonlinearities for
molecular contrast enhancement in Optical Coherence Tomography (OCT) is
presented. Numerical simulations for both coherent nonlinear processes are
performed in order to determine the properties of the signal expected at the
exit of the described nonlinear interferometer.
