# High Quality of Electromagnetically Induced Transparency Spectroscopy of 87Rb in a Buffer Gas Cell with Magnetic Field

## TL;DR

This study demonstrates high-resolution electromagnetically induced transparency spectroscopy of 87Rb vapor in a buffer gas cell under magnetic fields, enabling precise Zeeman splitting measurements and laser frequency locking.

## Contribution

It introduces a spectral method with Doppler broadening removal for high-resolution Zeeman splitting measurement in 87Rb vapor with buffer gas and magnetic field.

## Key findings

- EIT spectral lines become weaker and wider with buffer gas.
- Doppler broadening can be fully removed using a weighted least-square fit.
- The method allows high-resolution Zeeman splitting measurement and laser frequency locking.

## Abstract

We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87Rb vapor with a buffer gas in a magnetic field at room temperature. It is found that the spectral lines caused by the velocity selective optical pump effects get much weaker and wider when the sample cell mixed with a 5-Torr N2 gas while the EIT signal kept almost unchanged. A weighted least-square fit is also developed to remove the Doppler broadening completely. This spectral method provides a way to measure the Zeeman splitting with high resolution, for example, the {\Lambda}-type EIT resonance splits into four peaks on the D2 line of 87Rb in the thermal 2-cm vapor cell with a magnetic field along the electric field of the linearly polarized coupling laser. The high resolution spectrum can be used to lock the laser to a given frequency by tuning the magnetic field.