CPT atomic clock

The invention discloses a CPT atomic clock which is applied to the field of atomic frequency standards. The CPT atomic clock comprises a VCSEL, a 1/4 lambda wave plate, a lens and an optical cavity, and the VCSEL is used for generating laser required by light pumping of the CPT atomic clock; the lens and the optical cavity are arranged between the VCSEL and the 1/4 lambda wave plate; the lens is arranged on one side close to the VCSEL, and the lens is used for converging laser emitted by the VCSEL into Gaussian light; the optical cavity is arranged on one side close to the 1/4 lambda wave plate; the inner surface of the cavity mirror of the optical cavity comprises a reflecting mirror which is used for adjusting the amplitude of different frequencies in the laser signal so as to eliminate the high-order sideband. According to the scheme, the reflecting mirror of the optical cavity can be used for adjusting the amplitudes of different frequencies in the optical signals, eliminating high-order sidebands and att