Laser stabilization via absorption spectroscopy and active temperature feedback for chip-scale atomic magnetometer

The performance of chip-scale quantum sensors is often limited by laser frequency instabilities, particularly during long-term, uninterrupted operation. In this study, a dual-mode stabilization method that combines absorption spectroscopy (AS) with active temperature feedback (ATF) is developed. This method enables frequency locking and long-term wavelength-shift suppression simultaneously for vertical-cavity surface-emitting lasers (VCSELs). By integrating miniaturized light source and compact 4 × 4 × 4 mm³ alkali metal vapor cell, the magnetometer demonstrates great potential for miniaturized integration. This approach achieves a sensitivity of 12.4 fT/Hz^1/2, representing a 56 % improvement compared to systems relying solely on ATF stabilization. The proposed method resolves critical stability-compatibility trade-offs in chip-scale quantum sensors for demanding applications such as biomagnetic imaging and fundamental physics research, achieving an Allan deviation of 3.22 × 10⁻⁷ over 16 h.