Observation of a triangular-lattice pattern in nonlinear wave mixing with optical vortices

Abstract

Preparation, control, and measurement of optical vortices are increasingly important, as they play essential roles in both fundamental science and optical technology applications. Spatial light modulation is the main approach behind the control strategies, although there are limitations concerning the controllable wavelength. It is therefore crucial to develop approaches that expand the spectral range of light modulation. Here, we demonstrate the modulation of light by light in nonlinear optical interactions to demonstrate the identification of the topological charge of optical vortices. A triangular-lattice pattern is observed in light beams resulting from the spatial cross modulation between an optical vortex and a triangular shaped beam undergoing parametric interaction. Both up- and downconversion processes are investigated, and the far-field image of the converted beam exhibits a triangular lattice. The number of sites and the lattice orientation are determined by the topological charge of the vortex beam. In the downconversion process, the lattice orientation can also be affected by phase conjugation. The observed cross modulation works for a large variety of spatial field structures. Our results show that modulation of light by light can be used at wavelengths for which solid-state devices are not yet available.

Spatial Hadamard encoding with difference frequency generation

“…11 This close connection between DFG and SPDC has initiated a number of new methods that are more efficient to characterize and harness the spatial correlation of photon pairs. 12,13 Taking advantage of the high photon flux in the seeded process, we show that a practical image coding scheme using the spatial correlation of photon pairs can be realized through DFG.…”

Light correcting light with nonlinear optics

“…9,10 Beyond linear optics, structured light control with nonlinear optics has become topical of late, 11 shifting the focus of attention from wavelength change and efficiency to spatial modal creation, control, and detection. This has led to a reinvention of the field with a modern twist, ushering in new selection rules [12][13][14] and processes [15][16][17][18] while fostering widereaching applications, including spatial mode creation [19][20][21] and detection, 22,23 image processing [24][25][26][27] and filtering, 28 holography, [29][30][31] enhanced interferometry, 32 high-dimensional teleportation, 33,34 as well as the development of modern nonlinear materials. [35][36][37][38] Unfortunately, the spatial structure of light becomes distorted in complex channels, [39][40][41][42] arresting its full potential.…”

Remote transport of high-dimensional orbital angular momentum states and ghost images via spatial-mode-engineered frequency conversion

“…Recent years have also witnessed a growing interest in the nonlinear frequency conversion of structured light 5 , 18 . In spatial domain, it was demonstrated that using OAM light as fundamental frequency light source, one can realize the image processing and mode detection during the process of upconversion imaging 19 , 20 , and by shaping the spatial shape of the pump source, one can enhance the performance of high-dimensional OAM frequency interface 21 – 24 . In time-frequency domain, by using the dispersion-engineered sum-frequency generation, the quantum pulse gate for harnessing and selecting the time-frequency mode has been realized 25 , 26 .…”