Integrating planar photonics for multi-beam generation and atomic clock packaging on chip

Abstract

The commercialization of atomic technologies requires replacing laboratory-scale laser setups with compact and manufacturable optical platforms. Complex arrangements of free-space beams can be generated on chip through a combination of integrated photonics and metasurface optics. In this work, we combine these two technologies using flip-chip bonding and demonstrate an integrated optical architecture for realizing a compact strontium atomic clock. Our planar design includes twelve beams in two co-aligned magneto-optical traps. These beams are directed above the chip to intersect at a central location with diameters as large as 1 cm. Our design also includes two co-propagating beams at lattice and clock wavelengths. These beams emit collinearly and vertically to probe the center of the magneto-optical trap, where they will have diameters of ≈100 µm. With these devices we demonstrate that our integrated photonic platform is scalable to an arbitrary number of beams, each with different wavelengths, geometries, and polarizations.

Grating magneto-optical traps with complicated level structures

“…Our results will inform future development of compact quantum devices based on laser-cooled atoms or molecules. Type-II gMOTs appear to be of little utility, so quantum devices based on open shell molecules will prefer compact MOT geometries that preserve the symmetry of the six-beam MOT, such as photonic-integrated-circuit MOTs or pyramid MOTs [15,18,19]. Type-I gMOTs are effective for initial laser cooling and can load 'bright' or 'gray' optical molasses to achieve sub-Doppler temperatures [30,35].…”

“…This six-beam MOT configuration is generally realized in a laboratory, where up to 2 m 3 of space is used simply for the optics needed align the laser beams and form the MOT. In the last two decades, efforts to miniaturize MOTs have led to many different types of MOT geometries that attempt to simplify the optical setup [12,13], including mirror MOTs [14], pyramidal MOTs [15], tetrahedral MOTs [16,17], and photonic-integrated-circuit MOTs [18,19], and others.…”

Metasurfaces toward Optical Manipulation Technologies for Quantum Precision Measurement

“…[205,206] By combining optical metasurface with grating output, Ropp C et al, National Institute of Standards and Technology, designed and manufactured an integrated photonics package for the miniaturization of a strontium atomic clock. [207] Figure 9e is a schematic illustration of the setup of the magneto-optical trap, obtaining 3D cooling and trapping in a compact plane geometry, resulting in 12 circularly polarized beams of 10 mm diameter, which are designed to form the magneto optical trap in a small volume of a vacuum chamber containing strontium vapor. Figure 9f shows the threestage design for the beam emitter consisting of an evanescent coupler, meta-grating, and metasurface with each component contributing to beam shaping and polarization control.…”

“…e) Schematic illustration of the setup of the magneto-optical trap for a strontium atomic clock. Reproduced with permission under terms of the CC BY license [207]. Copyright 2023, The Authors, published by Springer Nature.…”

Ultra-sensitive absolute angular position sensing using pixelated metasurface

“…Ultra-sensitive angle sensing is critical for determining angular positions at the micro and nano scales, with wide-ranging applications in fields such as precision machines, chip assembly, robotics control, satellite attitude determination and biomedical devices. [1][2][3][4][5] Utilizing a laser beam to measure the rotation or deviation of the object, laser angle sensors offer advantages of high precision, high speed, non-contact operation, and strong resistance to interference. 6 Common optical systems used for precisely obtain angular information include autocollimators and angle interferometers.…”