Generation of dipole vortex array using spiral Dammann zone plates.

Area of Science:

• Optics
• Photonics
• Nanotechnology

Background:

• Vortex beams, characterized by orbital angular momentum, have unique properties for optical applications.
• Generating complex three-dimensional (3D) optical fields, such as dipole vortices, is crucial for advanced optical manipulation and microscopy.
• Diffractive optical elements offer versatile methods for shaping light fields.

Purpose of the Study:

• To propose and demonstrate a novel diffractive optical element, the spiral Dammann zone plate (SDZP), for generating 3D dipole vortex arrays.
• To experimentally validate the capability of SDZP in creating tunable 3D optical fields.

Main Methods:

• Fabrication of a 1×5 spiral Dammann zone plate (SDZP) using lithography and wet-etching.
• Combining the SDZP with a Dammann grating to generate 3D dipole vortex arrays.
• Experimental demonstration of 1×5 and 5×5×5 dipole vortex arrays using a low numerical aperture (NA=0.127) objective.

Main Results:

• Successful generation of a 1×5 coaxial dipole vortex array.
• Experimental demonstration of a 5×5×5 dipole vortex array by combining SDZP and a 5×5 Dammann grating.
• Tunable topological charges of the generated vortex arrays were confirmed by varying the incident vortex beam's charge.

Conclusions:

• The spiral Dammann zone plate (SDZP) is an effective tool for creating 3D dipole vortex arrays.
• The proposed method allows for the generation of complex, tunable optical fields in three dimensions.
• This technique holds promise for applications requiring precise control of light fields, such as optical trapping and microscopy.