Light intensity fluctuation insensitive faraday polarimeter for atomic magnetometer

Atomic Magnetometer has ranked the highest sensitive magnetometer in recent years. To realize a high performance atomic magnetometer, a well designed polarimeter is required to detect the atomic spin precession. Among various polarimeter techniques available, faraday polarimeter is suitable for high sensitive atomic magnetometer application due to its high angular sensitivity at low frequency range. However, this polarimeter is sensitive to light intensity fluctuation which will decrease the atomic magnetometer sensitivity and its long time performance. Instead of utilizing a light intensity feedback controlled system to active stabilize the light intensity, this paper proposed a faraday polarimeter with light intensity fluctuation compensation capability. The structure and mathematic model of this polarimeter was analyzed, experimental tests were performed. With this polarimeter, the light intensity fluctuation was decreased significantly to 0.001%, and an angular sensitivity of 10^-8 rad/Hz^1/2 has been achieved.