Chapter 3 - Harmonic Holography

Abstract

This chapter describes the principle and application of harmonic holography . It describes the theoretical foundation for scattering of optical harmonics by nanocrystals . The chapter discusses the coherence of optical second harmonics and explains the principle of harmonic holography, along with the first experimental demonstration of this principle. The chapter also describes the application of harmonic holography in 3D harmonic holographic microscopy for cell imaging. Second harmonic generation provides a unique means to achieve contrast in the coherent domain, enabling the use of holography in contrast imaging. The behavior of second harmonic generation at the nanoscale drastically differs from its counterpart in the bulk material due to the lack of phase matching. The dipole-like behavior of a nanocrystal that scatters in second harmonic frequency simplifies the estimation of the emission power of second harmonics. The theoretical predictions agree well with the experimental measurements. The chapter also shows that a harmonic holography is promising for constructing an ultrafast 4D contrast microscope with high spatial and temporal resolution. Harmonic holography records holograms using second harmonic signals scattered from SHG nanocrystals and an independently generated second harmonic reference. The first proof-of-principle experiment demonstrated a number of unique advantages of harmonic holography over direct imaging, including numerical aberration compensation and device noise elimination.