Electromagnetically Induced Transparency in $\Lambda$-systems of $^{87}Rb$ atom in magnetic field

The electromagnetically induced transparency (EIT) observations in two $\Lambda$-systems of $^{87}Rb$ atom, $|5^{2}S_{1/2} F=1\rangle \rightarrow |5^{2}P_{3/2} F'=1\rangle \leftarrow |5^{2}S_{1/2} F=2\rangle$ and $|5^{2}S_{1/2} F=1\rangle \rightarrow |5^{2}P_{3/2} F'=2\rangle \leftarrow |5^{2}S_{1/2} F=2\rangle$, have been investigated in detail and the results are found consistent with our proposed theoretical models. The second $\Lambda$-system provides EIT signal with higher magnitude than the first system, both in absence and in presence of an applied magnetic field. The observed steeper slope of the EIT signal in presence of the magnetic field can enable one to achieve tight frequency locking of lasers using these EIT signals.