Frequency Stabilization Using Polarization Spectroscopy and Cr-He Hollow Cathode Discharge

Polarization spectroscopy is used to lock a frequency-doubled Ti:Sapphire laser to the 425.5 nm ⁷S₃→⁷P₄⁰ transition of ⁵²Cr. A Cr−He hollow cathode discharge cell is designed and fabricated to produce Cr atom vapor instead of a high temperature cell. Without any modulation devices or lock-in amplifiers, a high signal-to-background level polarization spectroscopy signal is obtained. Moreover, a frequency fluctuation of ±295 kHz for more than one hour is achieved.