Metasurface-integrated elliptically polarized laser-pumped SERF magnetometers

Area of Science:

• Atomic physics and quantum sensing
• Nanophotonics and optical engineering
• Biomagnetism and medical imaging

Background:

• Spin-exchange relaxation-free (SERF) atomic magnetometers offer high sensitivity for biomagnetism.
• Conventional optical components hinder miniaturization and on-chip integration of SERF magnetometers.
• Elliptically polarized laser pumping is crucial for certain SERF magnetometer designs but requires bulky optics.

Purpose of the Study:

• To develop a compact, nanofabrication-compatible method for generating elliptically polarized light for SERF magnetometers.
• To demonstrate an on-chip polarization control solution for integrated atomic magnetometers.
• To enhance the feasibility of high-resolution biomagnetism imaging and portable atomic sensing.

Main Methods:

• A single-piece metasurface was designed using a computer-assisted optimization algorithm.
• The metasurface was fabricated on a SiO2 substrate using silicon-rich silicon nitride.
• An 87Rb vapor cell magnetometer utilizing the metasurface was constructed and tested.

Main Results:

• The metasurface achieved an ellipticity angle of 22.17° with <2% deviation from target polarization.
• The fabricated metasurface exhibited >80% transmittance at 795 nm.
• The resulting SERF magnetometer demonstrated a high sensitivity of 10.61 fT/Hz^1/2.

Conclusions:

• A metasurface-based approach enables efficient on-chip polarization control for SERF atomic magnetometers.
• This technology is a critical step towards fully integrated atomic magnetometers.
• The developed method facilitates advancements in high-resolution biomagnetism imaging and portable atomic sensors.