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Electro-optically forbidden or enhanced spin-to-orbital angular momentum conversion in a focused light beam
1State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, China.
Optics Letters
|April 3, 2008
Summary
We show how electric fields control spin-to-orbital angular momentum conversion in light beams using crystals. This electro-optic effect allows for controllable entanglement of photon properties.
Area of Science:
- Optics and Photonics
- Quantum Information Science
- Materials Science
Background:
- Spin-to-orbital angular momentum (SOM) conversion is crucial for light manipulation.
- The Pockels effect in uniaxial crystals allows for electric-field-induced changes in optical properties.
- Controlling photon entanglement is key for quantum technologies.
Purpose of the Study:
- To demonstrate electric-field control over SOM conversion in focused vectorial light beams.
- To investigate the role of spatial anisotropy in uniaxial crystals on SOM conversion.
- To explore the generation of entangled single photons with controllable spin and orbital angular momentum.
Main Methods:
- Utilizing a focused right-handed circularly polarized quasi-Gaussian beam.
- Employing a strontium barium niobate (SBN) uniaxial crystal exhibiting the Pockels effect.
- Applying an electric field to modulate the crystal's spatial anisotropy and observe SOM conversion.
Main Results:
- Demonstrated that electric fields can forbid or enhance SOM conversion.
- Identified a specific electric field (E(0)=-16.87 kV/cm) that forbids SOM conversion.
- Observed that generated single photons exhibit entanglement between spin and orbital angular momentum, controllable via the electric field.
Conclusions:
- Spatial anisotropy modulation via the Pockels effect offers a method to control SOM conversion.
- Electro-optic control of photon entanglement is achievable, opening avenues for quantum applications.
- The demonstrated effect provides a tunable platform for generating entangled photon states.
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