A Miniaturized Spin-Exchange Relaxation-Free Atomic Magnetometer Array Based on a 1 × 8 Planar Lightwave Circuit Waveguide Splitter

Using spin-exchange relaxation-free (SERF) atomic magnetometer array (AMA) in magnetocardiography and magnetoencephalography has presented a challenge in reducing its packing volume for integrated instrumentation and convenient maintenance. This study presents a novel, space-saving SERF AMA based on an 8-channel planar lightwave circuit (PLC) waveguide splitter with a compact footprint of 26 × 2.5 mm². The PLC splitting configuration allows the synchronization of the pump for a multisensor array, resulting in highly consistent performance among the sensors, with an impressive ultrahigh sensitivity of 34 fT Hz^−1/2 within a measurement bandwidth of 105 Hz. The PLC splitting method shows great promise in expanding the channel capacity of small-scale SERF AMAs, offering a cost-effective method for high-resolution medical diagnoses through functional magnetic imaging of humans. In addition, this method is expected to find applications in fields such as electromagnetic induction imaging, biological magnetism, and geomagnetic observation.