Broadband polarization-insensitive Mach-Zehnder interferometer for quantum manipulation based on thick silicon...

Area of Science:

• Integrated photonics
• Quantum optics

Background:

• Polarization-insensitive photonic devices are crucial for stable light manipulation in quantum systems.
• Random polarization changes degrade performance in optical communication and quantum applications.

Purpose of the Study:

• To design and demonstrate a polarization-insensitive Mach-Zehnder interferometer (MZI) on a nitride platform.
• To achieve high interference visibility and low polarization-dependent loss for quantum photonic applications.

Main Methods:

• Utilized particle-swarm optimization for a multimode interferometer with tailored edge shapes and sub-wavelength gratings.
• Incorporated segmented width-varied waveguides to counteract material birefringence in MZI arms.
• Fabricated the device on a 650 nm thick nitride platform.

Main Results:

• Achieved a single-photon interference visibility of approximately 98.7% even under active polarization scrambling.
• Demonstrated polarization-dependent loss below 0.3 dB over a 147 nm 1 dB bandwidth.
• Validated the device's robustness against polarization fluctuations.

Conclusions:

• The developed MZI is a promising component for polarization-insensitive integrated quantum photonic systems.
• Its high performance makes it suitable for applications like quantum key distribution.
• The design strategies effectively compensate for polarization-dependent effects in photonic devices.