CN-121983842-A - Single-sideband modulated Raman light generation device and method for cold atom interference

CN121983842ACN 121983842 ACN121983842 ACN 121983842ACN-121983842-A

Abstract

The invention discloses a single sideband modulated Raman light generating device and a method for cold atom interference, wherein the device comprises the following components: the device comprises a microwave source, a radio frequency source, a mixer, a radio frequency switch, a voltage-controlled attenuator, a band-pass filter, a phase shifter, a power divider, an IQ modulator, a phase adjusting power supply, a seed laser, a laser amplifier and a frequency doubling crystal. The microwave source is connected with the frequency mixer, the radio frequency switch is connected between the radio frequency source and the frequency mixer, the frequency mixer is connected with the voltage-controlled attenuator, the band-pass filter is connected between the voltage-controlled attenuator and the power divider, the power divider is also connected with the IQ modulator, the phase shifter is connected between the power divider and the IQ modulator, the phase adjusting power supply is connected with the IQ modulator, the seed laser is connected with the IQ modulator, and the laser amplifier is connected between the IQ modulator and the frequency doubling crystal. The invention can realize the generation and modulation of the Raman light by adopting one seed laser and one IQ modulator, has compact system structure and can improve the precision of interferometry.

Inventors

YANG SHENGJUN
YUAN LIANG

Assignees

南方科技大学

Dates

Publication Date: 20260505
Application Date: 20251224

Claims (10)

1. A single sideband modulated Raman light generating device for cold atom interference is characterized by comprising a microwave source, a radio frequency source, a mixer, a radio frequency switch, a voltage-controlled attenuator, a band-pass filter, a phase shifter, a power divider, an IQ modulator, a phase adjusting power supply, a seed laser, a laser amplifier and a frequency doubling crystal, wherein, The microwave source is connected with the mixer; The radio frequency switch is connected between the radio frequency source and the mixer; the mixer is connected with the voltage-controlled attenuator; The band-pass filter is connected between the voltage-controlled attenuator and the power divider; the power divider is also connected with the IQ modulator, and the phase shifter is connected between the power divider and the IQ modulator; The phase adjusting power supply is connected with the IQ modulator; The seed laser is connected with the IQ modulator, and the laser amplifier is connected between the IQ modulator and the frequency doubling crystal.
2. The single sideband modulated raman light generating device for cold atom interferometry of claim 1 wherein the voltage of the voltage controlled attenuator is adjusted to adjust the strength of the sideband radio frequency signal input to the IQ modulator.
3. The single sideband modulated raman light generating device for cold atom interferometry of claim 1 wherein in the state where the radio frequency switch is closed, the raman light generating device is in a single sideband modulated state and in the state where the radio frequency switch is open, the IQ modulator is in a non-operational state.
4. The single sideband modulated raman light generating device for cold atom interferometry of claim 1, further comprising a saturated absorption frequency stabilization device coupled to the seed laser for locking a raman laser to a predetermined frequency point.
5. The single sideband modulated Raman light generating apparatus for cold atom interferometry of claim 4, further comprising a polarizing beam splitter and an F-P scanning cavity, wherein the polarizing beam splitter is respectively coupled to the frequency doubling crystal, the saturated absorption frequency stabilizing device and the F-P scanning cavity, and the F-P scanning cavity is configured to monitor spectral components of the Raman laser in a single sideband operating state.
6. The single sideband modulated raman light generating device for cold atom interferometry of claim 1 wherein said IQ modulator comprises a dual cascaded M-Z interferometer, seed laser light input to said IQ modulator being modulated to produce optical field outputs having frequencies ω and ω±Δ.
7. A single sideband modulated raman light generation method based on a single sideband modulated raman light generation apparatus for cold atom interferometry as claimed in any one of claims 1 to 6, comprising the steps of: mixing frequency with a radio frequency source through a microwave source to generate a sideband radio frequency signal; Generating a radio frequency signal with the frequency delta through a voltage-controlled attenuator and a band-pass filter; dividing a sideband radio frequency signal into two paths of signals I and Q through a power divider, inputting the signals I and Q into an IQ modulator to modulate input seed laser, and generating an optical field with the frequencies of omega and omega + -delta; the phase difference between the signals of the I and Q paths is regulated to 90 degrees through a phase shifter, and the internal phase of the IQ modulator is controlled through a phase regulating power supply so as to output a single-sideband light field with the frequencies of omega and omega+delta; the optical field is amplified in optical power by a laser amplifier and converted into raman light by a frequency doubling crystal.
8. The method for generating single sideband modulated raman light according to claim 7, wherein the step of generating a sideband radio frequency signal having a frequency Δ by a voltage controlled attenuator and a bandpass filter comprises: Generating, by a mixer, a radio frequency signal comprising a plurality of frequency components having a frequency delta; the voltage of the voltage-controlled attenuator is adjusted to adjust the strength of the sideband radio frequency signal input to the IQ modulator; The redundant frequency components are filtered by a band-pass filter, so that the radio frequency signal with the frequency delta passes through.
9. The single sideband modulated raman light generation method of claim 7, further comprising the steps of: the Raman light is locked to a preset frequency point through a saturated absorption frequency stabilization device; the spectral components of the raman laser are monitored by the F-P scanning cavity in a single sideband operating state to determine the sideband suppression ratio and power allocation achieved by the voltage controlled attenuator and the phase adjusting power supply.
10. The single sideband modulated raman light generation method of claim 7, further comprising the steps of: the on-off of the microwave source is controlled by the radio frequency switch so as to realize the switching of the double-component Raman light and the single-component preparation light.

Description

Single-sideband modulated Raman light generation device and method for cold atom interference Technical Field The invention relates to the technical field of laser frequency conversion, in particular to a single sideband modulated Raman light generation device and method for cold atom interference. Background The atomic interferometer utilizes the material wave characteristics of atoms to carry out interferometry, shows extremely high measurement sensitivity and precision, and is widely applied to the fields of basic physical research and precise measurement such as gravity, gravity gradient, rotation, fine structure constant, magnetic field, universal gravitation constant and the like. For the matter wave interference experiment, the raman light generally refers to a two-component optical field with two-beam frequency differences being atomic hyperfine structure splitting (6.834 GHz for alkali metal rubidium atoms), and can generate two-photon resonance with atoms to couple two hyperfine ground state energy levels, while the atomic interferometer of a pulse sequence needs to utilize coherent raman light to realize beam splitting, reflection and beam combination operation of atomic matter waves, so how to generate high-quality low-noise raman light is a key technology of the atomic interferometer, and various methods for realizing the raman light include electro-optical modulation frequency shift and optical phase-locked loop for locking the frequency and phase between two independent lasers. The optical phase-locked loop has the advantages of low-frequency band (10-100 Hz) phase noise, however, the system has a complex structure, two independent laser systems are needed, the miniaturization and integration of the instrument are not facilitated, and in addition, the phase noise in a high-frequency range (> 1 MHz) is usually high due to the limitation of the bandwidth of an electronic feedback circuit. The general electro-optic modulation frequency shift scheme is compact and simple, but the modulation spectrum can naturally generate carrier wave (omega) and a plurality of symmetrical sidebands). One sideband and a carrier wave can be used for forming Raman two-photon transition, and redundant sidebands not only cause waste of laser power, but also can generate non-resonance interaction with other energy levels on atoms to generate additional Raman two-photon transition components, so that systematic errors are introduced, and the accuracy of interferometry is affected. Accordingly, the prior art is still in need of improvement and development. Disclosure of Invention In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a single sideband modulated raman light generating device and method for cold atom interference, so as to solve the problems of phase errors caused by the multi-band problem of the existing electro-optic modulator and the complex structure caused by the need of multiple lasers in the optical phase-locked loop. The technical scheme of the invention is as follows: In a first aspect, the invention provides a single sideband modulated Raman light generation device for cold atom interference, which comprises a microwave source, a radio frequency source, a mixer, a radio frequency switch, a voltage controlled attenuator, a band-pass filter, a phase shifter, a power divider, an IQ modulator, a phase adjusting power supply, a seed laser, a laser amplifier and a frequency doubling crystal, wherein, The microwave source is connected with the mixer; The radio frequency switch is connected between the radio frequency source and the mixer; the mixer is connected with the voltage-controlled attenuator; The band-pass filter is connected between the voltage-controlled attenuator and the power divider; the power divider is also connected with the IQ modulator, and the phase shifter is connected between the power divider and the IQ modulator; The phase adjusting power supply is connected with the IQ modulator; The seed laser is connected with the IQ modulator, and the laser amplifier is connected between the IQ modulator and the frequency doubling crystal. The invention is further arranged to adjust the strength of the sideband radio frequency signal input to the IQ modulator by adjusting the voltage of the voltage controlled attenuator. According to the invention, when the radio frequency switch is in a closed state, the Raman light generation device is in a single-sideband modulation state, and when the radio frequency switch is in an open state, the IQ modulator is in a non-working state. The device further comprises a saturated absorption frequency stabilization device, wherein the saturated absorption frequency stabilization device is connected with the seed laser and used for locking the Raman laser to a preset frequency point. The invention further provides a polarization spectroscope and an F-P scanning cavity, wherein the polarization spectroscope is respe