The 1529 nm Laser Stabilization Based on Dual-wavelength Modulation Transfer Spectroscopy

Modulation transfer spectroscopy (MTS) is a widely adopted sub-Doppler spectroscopic technique used for laser stabilization. In conventional MTS, modulation of the pump light is transferred to the probe light within a single atomic transition. A high population of atoms in the ground state is essential for achieving a high signal-to-noise ratio in MTS. Consequently, traditional MTS cannot be effectively applied to atomic transitions between higher energy levels, where the population of atoms is significantly lower. This work proposes a novel approach to stabilize a 1529 nm laser using dual-wavelength MTS. In this scheme, the pump and probe lights are generated by separate lasers, allowing for the modulation transfer process to occur between a 780 nm laser and a 1529 nm laser. Specifically, a prestabilized and modulated 780 nm laser is used as the pump light to interact with atoms, while the 1529 nm laser acts as the probe light to generate the servo signal necessary for locking the 1529 nm laser. This technique is versatile and can be applied to various atomic ensembles, including potassium (K), cesium (Cs), and lithium (Li).