Spontaneous parametric down-conversion in periodically poled KTP waveguides and bulk crystals

Area of Science:

• Quantum Optics
• Nonlinear Optics
• Materials Science

Background:

• Spontaneous parametric down-conversion (SPDC) is a key process for generating entangled photon pairs.
• Periodically poled waveguides offer potential advantages over bulk crystals for nonlinear optical processes.
• Potassium titanyl phosphate (KTP) is a widely used nonlinear optical material.

Purpose of the Study:

• To theoretically and experimentally compare the efficiency of SPDC in periodically poled waveguides and bulk KTP crystals.
• To quantify the pair generation rate in both configurations.
• To assess the suitability of waveguides for enhanced SPDC applications.

Main Methods:

• Theoretical modeling of SPDC in both waveguide and bulk geometries.
• Experimental setup for measuring SPDC pair generation rates.
• Utilized periodically poled waveguides and bulk KTP crystals as nonlinear media.
• Measured pair generation rate in a 1-nm spectral bandwidth.

Main Results:

• Achieved a waveguide SPDC pair generation rate of 2.9 x 10^6 pairs/s per mW of pump power within a 1-nm bandwidth.
• The waveguide generation rate was over 50 times higher than that measured in bulk KTP crystals.
• Theoretical predictions showed good agreement with experimental results.

Conclusions:

• Periodically poled waveguides significantly enhance the efficiency of spontaneous parametric down-conversion compared to bulk KTP crystals.
• Waveguides offer a more efficient platform for generating photon pairs for quantum information and optics applications.
• The demonstrated high generation rate highlights the practical advantages of waveguide-based SPDC.