Polarization effects in nonlinear interference of down-converted photons.

Area of Science:

• Nonlinear optics
• Quantum optics
• Photonics

Background:

• Spontaneous parametric-down conversion (SPDC) generates entangled photon pairs.
• Photon interference patterns are sensitive to polarization changes.
• Measuring infrared (IR) sample retardation typically requires specialized equipment.

Purpose of the Study:

• To develop novel, cost-effective methods for measuring IR sample retardation.
• To leverage visible light components for IR optical measurements.
• To investigate polarization effects in nonlinear interference.

Main Methods:

• Utilizing frequency nondegenerate spontaneous parametric-down conversion (SPDC) to generate visible (signal) and IR (idler) photons.
• Implementing a nonlinear Michelson interferometer to analyze signal photon interference.
• Introducing polarization rotation to idler photons via a birefringent sample and observing its effect on signal photon interference.

Main Results:

• Demonstrated induced coherence where signal photon interference depends on idler photon polarization rotation.
• Developed two new methods for IR sample retardation measurement with high accuracy.
• Achieved accuracy comparable to industrial-grade optical elements.

Conclusions:

• The developed IR polarimetry technique offers a cost-effective and accurate solution for material research.
• This method enables precise optical inspection and quality control using readily available visible light components.
• The study highlights the potential of nonlinear interference for advanced optical metrology.