Page 51 - 2024S

44 UEC Int’l Mini-Conference No.52

Towards the Development of a Compact Beam Expander Design for

Trapping Ultra-Cold Atoms

*
Ahmed SOHAIL , Tetsuo KISHIMOTO
Department of Engineering Science
The University of Electro-Communications
Tokyo, Japan

Keywords: Magneto-optical trap (MOT), Photonic integrated circuit (PIC), bulk optics, far-field
diffraction.

Abstract
For several decades, developing compact MOTs has received a lot of attention. To improve functionality
and control and meet the growing demand for portability in these systems, photonic integration is
becoming more and more desirable. Numerous challenges emerge as the design becomes more complex.
For instance, creating light beams with large mode expansions and numerical apertures requires a
sophisticated arrangement of bulk optics. We are planning a beam expander design based on a thin optical
structure that makes a possible use of the light diffraction phenomenon. This design is aimed to yield
optimal outcomes in terms of compactness and efficiency as compared to PIC-based structures. The
behavior of the beam is estimated and calculated in Fresnel and Fraunhofer regions using mathematical
frameworks, including the Rayleigh-Sommerfeld diffraction integral, Kirchhoff's formula, and Huygens-
Fresnel principle. Furthermore, this study aims to investigate the light beam's polarization effect and how
the light beam's diffraction angle affects the restoring force exerted on the atoms within the MOT.