Coherent Population Trapped Atomic Frequency Standard and the Method of Improving Its Short-term Stability

Abstract

The invention discloses a coherent population trapping an atomic frequency standard and a method for improving its short-term stability, belonging to the field of atomic frequency standards. The atomic frequency standard includes: a voltage-controlled crystal oscillator; a linear polarization excitation unit, which is used to generate a microwave search signal according to the output frequency of the voltage-controlled crystal oscillator; a physical unit, which is used to generate an optical detection signal under the action of the microwave search signal; a servo loop, It is used to perform synchronous phase detection on the optical detection signal to generate a synchronous phase detection signal; the control unit is used to generate a correction voltage based on the synchronous phase detection signal to act on the voltage-controlled crystal oscillator; the system relaxation time detection unit is used to detect the atomic frequency standard system Relaxation time Δt; the control unit is also used for timing control of the optical switch and servo loop in the physical unit according to the system relaxation time Δt, after controlling the optical switch in the physical unit to be turned on for N Δt time lengths, control The servo loop performs synchronous phase detection on the optical detection signal generated by the physical unit.

Description

technical field [0001] The invention relates to the field of atomic frequency standards, in particular to a coherent population trapping atomic frequency standard and a method for improving its short-term stability. Background technique [0002] Coherent Population Trapping (English: Coherent Population Trapping, referred to as: CPT) atomic frequency standard is a new type of atomic frequency standard realized by using a quantum interference phenomenon generated by the interaction between atoms and coherent lasers. The miniaturized atomic frequency standard has smaller volume and power consumption than the hydrogen atomic frequency standard and cesium atomic frequency standard, and is even much smaller than the current rubidium atomic frequency standard with the smallest volume and power consumption. [0003] The principle of the CPT atomic frequency standard is to use microwaves to modulate the laser to obtain the interaction between the two-color coherent laser and the ato...

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Problems solved by technology

[0005] When the two-color coherent laser interacts with atoms, a large number of atoms accumulate in the ground state hyperfine sub-level state, forming a polarized dark state phenomenon and cannot participate in the preparation of the CPT atomic state, thereby affecting the system signal-to-noise ratio of the CPT atomic frequency standard, which is not conducive to CPT Short-term Stability of Atomic Frequency Standard System

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