The biaxial nonlinear crystal BiB₃O₆ as a polarization entangled photon source using non-collinear type-II parametric...

Area of Science:

• Quantum optics
• Materials science for photonics

Background:

• Nonlinear optical crystals are essential for generating entangled photons.
• Bismuth borate (BiB₃O₆ or BiBO) is a biaxial crystal with potential for nonlinear optical applications.
• Beta-barium borate (β-BaB₂O₄ or BBO) is a well-established crystal for entangled photon sources.

Purpose of the Study:

• To fully characterize the bismuth borate (BiB₃O₆ or BiBO) crystal for use as a polarization entangled photon source.
• To compare the performance of BiBO with the conventional beta-barium borate (BBO) crystal.
• To investigate key crystal design parameters for optimizing entangled photon generation.

Main Methods:

• Utilizing non-collinear type-II spontaneous parametric down-conversion (SPDC).
• Analyzing crystal cutting angles, photon polarization, effective nonlinearity, spatial and temporal walk-offs, crystal thickness, and pump laser bandwidth.
• Experimentally generating polarization-entangled photons and measuring generation rates.

Main Results:

• BiBO demonstrates high rates of polarization-entangled photon generation.
• BiBO enhances the generation rate by a factor of 2.5 compared to BBO, equivalent to a 2.5x increase in pump power.
• Detailed characterization of BiBO's relevant parameters for SPDC is provided.

Conclusions:

• Bismuth borate (BiB₃O₆ or BiBO) is a superior crystal for generating polarization-entangled photons compared to BBO.
• The enhanced generation rate from BiBO is critical for advancing the creation of multiphoton entangled states.
• BiBO offers a significant practical improvement for quantum information applications requiring high entangled photon flux.