Study on modulation transfer spectroscopy of Rb atoms

Closed-loop frequency stabilization-'laser locking'-is required for laser cooling, precision spectroscopy and atomic clocks. We compare the modulation transfer with the direct modulation in signal intensity and noise. By calculating, we get the conclusion that the ratio of signal intensity between modulation transfer scheme and the direct modulation scheme is 1.13:1 whereas the SNR of the modulation transfer scheme and the direct modulation scheme is almost 1.17:1, when the power of the laser is equal and without considering the details of interaction between lights and atoms. And we experimentally realized a stable external-cavity diode laser via MTS referencing on the Rb D2 lines at 780nm.