Implementation method for difference detection of coherent population trapping magnetometer

Abstract

The present invention discloses an implementation method for difference detection of a coherent population trapping magnetometer. The method employs the linear polarization polychromatic light outputted by VCSEL and the atom effect in a magnetic field to extract CPT signals by means of an Faraday effect through a difference detection technology so as to effectively inhibit the AM and FM-AM noise generated by laser in signals, eliminate background noise generated by polychromatic light useless optical frequency components, improve the measurement precision of a CPT magnetometer, and extend the detection range of the magnetic field intensity through the difference.

Description

technical field [0001] The invention relates to the field of atomic magnetometers, and in particular to a method for realizing a differential detection coherent population and trapping magnetometer. Background technique [0002] Magnetometers have extremely important applications in the fields of geomagnetic field detection, space physics, and biomedicine. The atomic magnetometer is a device that uses the Zeeman effect of atoms in a magnetic field to reverse the magnetic field information. The miniature atomic magnetometer realized by the CPT phenomenon is only 12mm in size 3 , the power consumption is only 195mW, and the sensitivity can reach 50pT / Hz 1 / 2 . [0003] Energy level Zeeman movement makes the hyperfine energy level split of alkali atoms in the magnetic field change, and 87 Rb atom as an example, according to the Breit-Rabi formula ( is the reduced Planck constant, ω hfs is the frequency difference between the two energy states whose ground state magnetic ...

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Problems solved by technology

[0004] The popular scheme has the advantage of being easy to implement a small magnetometer, but it also has some disadvantages: using a single left-handed or right-handed circularly polarized dichroic light to interact with atoms will pump some atoms into a polarized dark state, thus reducing the number of atoms participating in the CPT resonance , to reduce the amplitude of the CPT signal; in the FM light output by the VCSEL, only ±1 sidebands contribute to the CPT signal, and other optical frequency components do not contribute to the CPT signal, and the non-contributing optical frequency components are also detected, resulting in background optical noise of the signal Large; VCSEL output laser power fluctuations cause strong amplitude (AM) noise; VCSEL output laser has a wide bandwidth, and the frequency jitter is converted into amplitude fluctuations through the CPT signal, which generates frequency-amplitude conversion (FM-AM) noise

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