Optical Image Self-Convolution Based on Second-Harmonic Generation With a Single Spatial Light Modulator

By combining optical Fourier transform with second-harmonic generation (SHG) from infrared to visible region in a periodically poled Magnesium-doped Lithium Niobate (PPLN) crystal, we present a simple yet efficient experiment to revisit the optical implementation of image self-convolution. In contrast to previous scheme, here the main feature is the holographic gratings we prepare by a phase-only spatial light modulator that enables a deeper understanding on the centrosymmetry for intensity images, and particularly, the conjugate symmetry for both intensity and phase images. We manifest both cases by observing the real-time autocorrelation peaks that appear gradually in the output SHG signals. As our optical scheme possesses the inherent capacity of parallel processing, it will find potential in pattern recognition, particularly, for infrared remote sensing.