Improvement of saturated absorption frequency stabilization of diode laser at 852 nm

In order to comppress the fluctuation of frequency and improve the frequency stability of laser, we demonstrate a wavelength-modulation-locking laser source which has a continuous tuning range around the central wavelength of 852 nm. The system consists of a grating-feedback external cavity diode laser part, an error signal obtaining part and a proportional-integral feedback control part. Two channels are conducted to lock the laser at the hyperfine transition peaks and around the peaks respectively. And the two channels can be switched expediently. When locking at the peaks, the third derivation of the spectrum signal is carried out as an error signal to control the feedback loop. And when locking at the frequency points around the peaks, the output spectrum line is used as the feedback control signal directly. The locking range of the laser frequency is expanded and the fluctuation of the laser is comppressed within the range of 1.15 MHz.