Infrared upconverted image edge enhancement using spiral phase filter

We present a theoretical and experimental demonstration of infrared upconverted image edge enhancement, acquired with quasi-phase-matching for the sum-frequency conversion process and a spiral phase filter. By illuminating a transmission mask with a 1559.5 nm Gaussian beam to create an infrared image and pumped with a 1064 nm vortex beam, an upconverted edge-enhanced image at 632.5 nm is generated. The theoretical model for the process is derived, which well explains the deviation of experimental results. The proposed technique can be further adapted for other spectral regions and nonlinear optical processes.