Shaping light beams in nonlinear processes using structured light and patterned crystals

Sivan Trajtenebrg-Mills,Ady Arie

doi:10.1364/ome.7.002928

Abstract

Shaping light in second order nonlinear interaction is a compact way of controlling both shape and frequency of the output, a desirable trait for many different applications such as optical communication, particle manipulation, microscopy, spectroscopy, and quantum information. The use of patterned nonlinear crystals, combining holographic methods with electric field poling, has proven a useful way to create arbitrary one- and two-dimensional shapes, as well as beams that follow curved trajectories. Using structured light as an input beam has also been shown to produce light with special properties, such as vortex beams carrying orbital angular momentum, curved Airy beams, and others. We review the latest advances in the field.

Highlights

The manipulation and control of light beams attracted great interest over the past years
Methods which control the SH shape by manipulating the nonlinear coefficient of the crystal rely on custom made photonic crystals, where the sign of the second order susceptibility χ (2) is changed along the crystal according to a pre-designed pattern
The reconstructed wave must be separated from the reference wave. This is achieved by off-axis Fourier holography, i.e. imposing a carrier frequency upon the hologram, causing the reconstructed beam to split into multiple diffraction orders in the far field, whose angle θm can be calculated from the carrier frequency by θm = mλ fcarrier, where m is the diffraction order and lambda is the wavelength

Summary

Introduction

The manipulation and control of light beams attracted great interest over the past years. Shaping the beams in the nonlinear process itself is a compact way of controlling the generated light, which would be otherwise manipulated separately using different optical devices, such as lenses, phase and amplitude masks and others. It is especially useful in wavelengths where these are not abundant, or in when the setup space is limited (such as within a microscope). Self-accelerating beams such as the Airy beam was demonstrated [8,21], and lately beams with arbitrary caustic trajectories have been generated [22]

Theoretical background

Fabrication of poled crystals

Nonlinear beam shaping with nonlinear holograms

Control of the beam trajectory

Shaping beams with structured pump source

Summary