Three-Dimensional Magneto-Optical Trap Beam Delivery with Scalable Wafer-Level Optics

Area of Science:

• Atomic, Molecular, and Optical Physics
• Photonics and Integrated Optics
• Nanotechnology

Background:

• Magneto-optical traps (MOTs) are crucial for cold atom preparation in precision applications.
• Conventional free-space optics for MOTs are bulky, costly, and hard to align.
• Existing photonic integrated circuit (PIC) MOTs still require external optics alignment, hindering miniaturization.

Purpose of the Study:

• To present a simplified, compact, and scalable beam delivery architecture for PIC-based MOTs.
• To eliminate the need for external optical components in MOT systems.
• To enable foundry-compatible fabrication of integrated MOT beam delivery.

Main Methods:

• Developed a two-wafer beam delivery architecture for PIC-based MOTs.
• Utilized inverse design and optimization for a multifunctional grating coupler and integrated metasurface retroreflectors.
• Designed components for circularly polarized light delivery of ⁸⁷Rb atoms at 780 nm.

Main Results:

• Experimentally demonstrated a retroreflector with 74% efficiency and 0.85 ellipticity.
• Simulated a grating coupler with 20% out-coupling efficiency and 0.85 polarization ellipticity.
• The proposed architecture significantly simplifies alignment and offers a compact footprint.

Conclusions:

• The novel two-wafer architecture successfully integrates all beam delivery optics onto a PIC.
• This approach eliminates external optics, simplifying alignment and reducing complexity for MOT systems.
• The design is scalable, foundry-compatible, and suitable for miniaturized precision atomic applications.