Laser mode-hopping assisted all-optical single beam pulsed atomic magnetometer

• Published in: arXiv.org
• Main Authors: Yoon, Ji Hoon, Hong, Sang Hyuk, Jeong, Taek, Yim, Sin Hyuk, Shim, Kyu Min, Lee, Sangkyung
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 02.04.2024
• Subjects: Bragg reflectors; Cramer-Rao bounds; Current modulation; DBR lasers; Electrons; Faraday effect; Frequency counters; Laser modes; Lasers; Lower bounds; Magnetometers; Optical pumping; Polarization (spin alignment); Sensitivity
• ISSN: 2331-8422

We demonstrate an all-optical single beam pulsed atomic magnetometer assisted by laser mode-hopping in a distributed Bragg reflector (DBR) laser. We implement a temporal sequence of the laser current; sinusoidal current modulation including the laser mode-hop current for synchronous optical pumping and the following constant current for paramagnetic Faraday rotation measurements to probe the free induction decay (FID) of transverse \(^{87}\)Rb spin polarization. Repetitive sudden frequency shifts of 20 GHz around the pressure-broadened \(^{87}\)Rb spectra originating from laser mode-hopping enables discontinuous optical pumping modulation with a large depth which enhances transverse spin polarization. We achieve a sensitivity of 3.77 pT/Hz\(^{1/2}\) in a magnetic field of 14 \(\mu\)T, limited by the performance of the frequency counter. The Cramer-Rao lower bound (CRLB) of the sensitivity due to the non-magnetic noise such as photon shot-noise is 191 fT/Hz\(^{1/2}\). Our approach based on laser mode-hopping can be applied to miniaturization of all-optical atomic magnetometers with sub-pT/Hz\(^{1/2}\) sensitivities.