Integrated Polarization-Splitting Grating Coupler for Chip-Scale Atomic Magnetometer.

Area of Science:

• Optoelectronics
• Nanophotonics
• Atomic Magnetometry

Background:

• Atomic magnetometers (AMs) are highly sensitive instruments for measuring biomagnetic fields.
• There is a growing need for miniaturized, cost-effective AMs using nanophotonics and CMOS technology.
• Current chip-scale AM development requires efficient optical components for signal detection.

Purpose of the Study:

• To demonstrate an integrated polarization-splitting grating coupler for chip-scale atomic magnetometers.
• To achieve efficient light coupling and polarization splitting at the rubidium D1 transition wavelength (795 nm).
• To enable differential detection of ultra-weak magnetic fields using compact planar optical components.

Main Methods:

• Design and fabrication of a polarization-splitting grating coupler using silicon nitride on silicon dioxide.
• Integration of the coupler with a silicon substrate, ensuring CMOS compatibility.
• Utilizing the coupler to process linearly polarized probe light affected by magnetically induced circular birefringence in an alkali medium.

Main Results:

• Demonstrated efficient coupling and polarization splitting of light at 795 nm.
• The device enables differential detection of optical rotation caused by magnetic fields.
• The fabricated coupler is compatible with standard CMOS nanofabrication processes.

Conclusions:

• The integrated grating coupler is a key enabling component for on-chip atomic magnetometers.
• This technology paves the way for compact, multi-channel, high-spatial-resolution biomagnetic imaging instruments.
• The developed device supports the advancement of miniaturized and cost-effective magnetic field sensing.