A three-dimensional magneto-optical trap (MOT), acting as an efficient method for producing cold atoms from room-temperature atomic vapor, has been widely used to develop atomic sensors. Various compact MOTs using a single laser beam have been reported, simplifying apparatuses and leading to miniaturized devices. Here, we propose single-beam MOTs based on back-to-back pyramidal and conical mirrors. In such back-to-back mirrors, a MOT trapping volume is formed by an incident laser beam, a retroreflected beam, and multiple reflections from the mirror surfaces. We present the design of back-to-back mirrors and a series of compact MOT configurations, with the potential of increasing access to the MOT and simultaneously creating multiple MOTs. We demonstrate a MOT in a back-to-back conical mirror, loading \ensuremath{\sim}1 \ifmmode\times\else\texttimes\fi{}
107 87Rb atoms from background vapor and cooling the atoms to \ensuremath{\sim}7 \textmu{}K using polarization gradients. Single-beam MOTs based on back-to-back mirrors contribute to building compact and scalable cold-atom-based sensors.
A Magneto-Optical Trap (MOT) for
87Rb atoms near the surface of a dielectric coated mirror at the top of a small
20×25×40mm3 cell has been observed. Two beams of
3.3mW/cm2 were used for optical cooling and an anti-Helmholtz magnetic field with a spatial gradient of 9.1 G/cm was used for magnetic trapping. The thickness of the mirror coated on a cover glass was less than
100μm . The mirror covered the top of a cell and the atom-chip was located outside the vacuum in order to exploit the long life time of the mirror and easy operation of the chip. The trapping position was found 5 mm beneath the mirror surface. The number of trapped atoms was roughly
3×107 atoms and the temperature was approximately a few tens mK. In this paper, we describe the construction of the mirror-MOT in detail.