A robust performance evaluation method for vapor cells used in magnetometers is proposed in this work.The performance of the vapor cell determines the sensitivity of the magnetic measurement,which is the core paramete...A robust performance evaluation method for vapor cells used in magnetometers is proposed in this work.The performance of the vapor cell determines the sensitivity of the magnetic measurement,which is the core parameter of a magnetometer.After establishing the relationship between intrinsic sensitivity and the total relaxation rate,the total relaxation rate of the vapor cell can be obtained to represent the intrinsic sensitivity of the magnetometer by fitting the parameters of the magnetic resonance experiments.The method for measurement of the total relaxation rate based on the magnetic resonance experiment proposed in this work is robust and insensitive to ambient noise.Experiments show that,compared with conventional sensitivity measurement,the total relaxation rate affected by magnetic noise below 0.9 n T,pump light frequency noise below 1.5 GHz,pump light power noise below 9%,probe light power noise below 3%and temperature fluctuation of 150±3℃deviates by less than 2%from the noise-free situation.This robust performance evaluation method for vapor cells is conducive to the construction of a multi-channel high-spatial-resolution cardio-encephalography system.展开更多
Zero-field single-beam atomic magnetometers with transverse parametric modulation for ultra-weak magnetic field detection have attracted widespread attention recently.In this study,we present a comprehensive response ...Zero-field single-beam atomic magnetometers with transverse parametric modulation for ultra-weak magnetic field detection have attracted widespread attention recently.In this study,we present a comprehensive response model and propose a modification method of conventional first harmonic response by introducing the second harmonic correction.The proposed modification method gives improvement in dynamic range and reduction of linearity error.Additionally,our modification method shows suppression of response instability caused by optical intensity and frequency fluctuations.An atomic magnetometer with single-beam configuration is built to compare the performance between our proposed method and the conventional method.The results indicate that our method’s magnetic field response signal achieves a 5-fold expansion of dynamic range from 2 nT to 10 nT,with the linearity error decreased from 5%to 1%.Under the fluctuations of 5%for optical intensity and±15 GHz detuning of frequency,the proposed modification method maintains intensityrelated instability less than 1%and frequency-related instability less than 8%while the conventional method suffers 15%and 38%,respectively.Our method is promising for future high-sensitive and long-term stable optically pumped atomic sensors.展开更多
Optically pumped magnetometers(OPMs)have developed rapidly in the bio-magnetic measurement field,which requires lasers with stable frequency and intensity for high sensitivity.Herein we stabilize a vertical-cavity sur...Optically pumped magnetometers(OPMs)have developed rapidly in the bio-magnetic measurement field,which requires lasers with stable frequency and intensity for high sensitivity.Herein we stabilize a vertical-cavity surface-emitting laser(VCSEL)without any additional setup except for the parts of an OPM.The linewidth of the absorption spectrum as a frequency reference is broadened to 40 GHz owing to pressure broadening.To enhance performance,the VCSEL injection current and temperature are tuned simultaneously using a closed-loop control system.The experiments reveal that the VCSEL frequency stability achieves 2×10^(-7) at an average time of 1 s,and the intensity noise is 1×10^(-6)V/Hz^(1/2) at 1-100 Hz.This approach is useful for suppressing OPM noise without additional sensor probe parts.展开更多
We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam...We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam DC mode achieves a sensitivity of 7 fT=Hz^(1/2) with probe noise below 4 fT=Hz^(1/2) and working bandwidth over 65 Hz.This mode is designed to precisely measure the noise floor of a mu-metal magnetic shield.The single-beam modulation mode(sensitivity 20 fT=Hz^(1/2))exhibits bandwidth characteristics suitable for biomagnetic measurements.Thus,our design is suitable for a miniaturized OPM with multiple functions,including magnetic-shield background noise measurement and medical imaging.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62173020 and 62103381)。
文摘A robust performance evaluation method for vapor cells used in magnetometers is proposed in this work.The performance of the vapor cell determines the sensitivity of the magnetic measurement,which is the core parameter of a magnetometer.After establishing the relationship between intrinsic sensitivity and the total relaxation rate,the total relaxation rate of the vapor cell can be obtained to represent the intrinsic sensitivity of the magnetometer by fitting the parameters of the magnetic resonance experiments.The method for measurement of the total relaxation rate based on the magnetic resonance experiment proposed in this work is robust and insensitive to ambient noise.Experiments show that,compared with conventional sensitivity measurement,the total relaxation rate affected by magnetic noise below 0.9 n T,pump light frequency noise below 1.5 GHz,pump light power noise below 9%,probe light power noise below 3%and temperature fluctuation of 150±3℃deviates by less than 2%from the noise-free situation.This robust performance evaluation method for vapor cells is conducive to the construction of a multi-channel high-spatial-resolution cardio-encephalography system.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB2002405)the National Natural Science Foundation of China(Grant No.61903013)。
文摘Zero-field single-beam atomic magnetometers with transverse parametric modulation for ultra-weak magnetic field detection have attracted widespread attention recently.In this study,we present a comprehensive response model and propose a modification method of conventional first harmonic response by introducing the second harmonic correction.The proposed modification method gives improvement in dynamic range and reduction of linearity error.Additionally,our modification method shows suppression of response instability caused by optical intensity and frequency fluctuations.An atomic magnetometer with single-beam configuration is built to compare the performance between our proposed method and the conventional method.The results indicate that our method’s magnetic field response signal achieves a 5-fold expansion of dynamic range from 2 nT to 10 nT,with the linearity error decreased from 5%to 1%.Under the fluctuations of 5%for optical intensity and±15 GHz detuning of frequency,the proposed modification method maintains intensityrelated instability less than 1%and frequency-related instability less than 8%while the conventional method suffers 15%and 38%,respectively.Our method is promising for future high-sensitive and long-term stable optically pumped atomic sensors.
基金supported by the National Key R&D Program of China(No.2018YFB2002405)the National Natural Science Foundation of China(No.61903013)。
文摘Optically pumped magnetometers(OPMs)have developed rapidly in the bio-magnetic measurement field,which requires lasers with stable frequency and intensity for high sensitivity.Herein we stabilize a vertical-cavity surface-emitting laser(VCSEL)without any additional setup except for the parts of an OPM.The linewidth of the absorption spectrum as a frequency reference is broadened to 40 GHz owing to pressure broadening.To enhance performance,the VCSEL injection current and temperature are tuned simultaneously using a closed-loop control system.The experiments reveal that the VCSEL frequency stability achieves 2×10^(-7) at an average time of 1 s,and the intensity noise is 1×10^(-6)V/Hz^(1/2) at 1-100 Hz.This approach is useful for suppressing OPM noise without additional sensor probe parts.
基金This work was supported by the National Key R&D Program of China(No.2018YFB2002405)the National Natural Science Foundation of China(No.61903013).
文摘We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam DC mode achieves a sensitivity of 7 fT=Hz^(1/2) with probe noise below 4 fT=Hz^(1/2) and working bandwidth over 65 Hz.This mode is designed to precisely measure the noise floor of a mu-metal magnetic shield.The single-beam modulation mode(sensitivity 20 fT=Hz^(1/2))exhibits bandwidth characteristics suitable for biomagnetic measurements.Thus,our design is suitable for a miniaturized OPM with multiple functions,including magnetic-shield background noise measurement and medical imaging.
