Effects of axial field components on second harmonic generation microscopy

The effects of the axial field components of a focused beam under high NA on the second harmonic generation (SHG) in collagen was examined using a vectorial approach. We find that with high NA, the cross-component terms that are most likely to have an effect on SHG will be ExEx, ExEy, ExEz and EzEz as a result of tight focusing. By considering the tensor and the presence of the other electric field components the possibility of different polarization states of the generated second harmonic as a result of the nonlinear susceptibility tensor making it possible to generate radially polarized modes with linearly polarized beams. (c) 2006 Optical Society of America.