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Adjustable diffractive spiral phase plates
Optics Express
|April 4, 2015
Summary
Researchers created adjustable Moiré diffractive spiral phase plates. This optical device allows continuous tuning of helical charge for generating various Laguerre-Gauss (LG) beams.
Area of Science:
- Optics and Photonics
- Diffractive Optics
- Beam Shaping
Background:
- Spiral phase plates (SPPs) are crucial for generating optical vortex beams.
- Controlling the helical charge of SPPs typically requires fabricating new elements for each desired charge.
Purpose of the Study:
- To develop and demonstrate a novel Moiré diffractive spiral phase plate (MDSPP) with continuously adjustable helical charge.
- To enable flexible generation of Laguerre-Gauss (LG) beams with tunable properties.
Main Methods:
- Fabrication of two axially stacked diffractive elements with conjugate structures using gray-scale photolithography.
- Utilizing the mutual rotation angle between the stacked elements to control the joint transmission function.
- Experimental demonstration using a TEM(00) beam as input.
Main Results:
- Successful fabrication of MDSPPs with 200 nm pixel size and 128 phase levels in fused silica.
- Experimental generation of approximated Laguerre-Gauss (LG) beams with continuously adjustable helical charge.
- Demonstration of a variable radius for the ring-shaped intensity distribution of the generated LG beams.
Conclusions:
- The developed MDSPP offers a versatile platform for on-demand generation of optical vortex beams.
- This technology provides a flexible and continuous method for tuning the helical charge and beam properties.
- The findings have potential applications in optical manipulation, communication, and quantum information processing.
