Abstract
We use the method of saturation absorption spectroscopy and third harmonic technique to construct the frequency stabilization system of near infrared rays (775~807 nm) external cavity diode laser (ECDL) to the iodine molecule. And use the 120 cm and 50 cm iodine absorption cell and keep temperature of the cell on 600℃ to improve the absorption signal. The third derivative of the iodine hyperfine absorption signal was used as the error signal. The accuracy of absolute frequency will be less than 100 kHz. Otherwise, since the wavelength of the second harmonic generation (SHG) of 1.55 μm DFB diode laser will operate in the wavelength range of the previous system. The doubler was waveguide periodically-poled LiNbO (PPLN). We obtain a second harmonic power of 1.3 mW at 777 nm. This SHG will be an another light source of the frequency stabilization system. We provide a new method of the laser frequency stabilization. This method will be a new option of the optical fiber communication and the laser spectroscopy.