CN102377431B - Coherent population trapping atomic clock and realization method thereof - Google Patents
Coherent population trapping atomic clock and realization method thereof Download PDFInfo
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- CN102377431B CN102377431B CN 201010248337 CN201010248337A CN102377431B CN 102377431 B CN102377431 B CN 102377431B CN 201010248337 CN201010248337 CN 201010248337 CN 201010248337 A CN201010248337 A CN 201010248337A CN 102377431 B CN102377431 B CN 102377431B
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Abstract
The invention provides a coherent population trapping atomic clock and a realization method thereof. The realization method of the coherent population trapping atomic clock comprises the following steps of: filtering an alkali metal gas electrodeless lamp and taking the filtered alkali metal gas electrodeless lamp as a pumping light source for pumping an alkali metal gas atom in a gas chamber, realizing the reverse of the population and then forming alkali metal gas laser under the action of a laser resonant cavity; processing the alkali metal gas laser and carrying out phase locking to obtain dual-frequency laser or carrying out modulation to obtain n-frequency laser; carrying out laser pumping on an alkali metal atomic bubble by adopting the obtained laser; and generating a signal with standard frequency according to a signal generated by carrying out the laser pumping on the alkali metal atomic bubble by the laser. According to the coherent population trapping atomic clock and the realization method thereof disclosed by the invention, the alkali metal laser is used as a laser light source of the CPT (Coherent Population Trapping) atomic clock, the stability of frequency of the alkali metal laser is enhanced and the precision and the reliability of the CPT atom clock are improved. In addition, the service life of the alkali metal gas as a grain medium is long; and even if an alkali metal laser works at higher temperature, the service life of the alkali metal laser can also reach twenty years and further the service life of the CPT atom clock is prolonged.
Description
Technical field
The present invention relates to atomic clock and frequency standard technical field, relate in particular to a kind of coherent layout number imprison (Coherent Population Trapping is called for short CPT) atomic clock and its implementation.
Background technology
The narrow linewidth of the coherent dark attitude that forms owing to CPT when the CPT atomic clock is based on coherent laser and Three-level Atom that two bundle frequency differences equal the clock jump frequency of atom and interacts is composed and the atomic clock that microwave radiation realized that is concerned with.
The used laser of present international CPT atomic clock all is a semiconductor laser, Vcsel that especially can high frequency modulated (Vertical Cavity Surface EmittingLaser is called for short VCSEL).Usually, semiconductor laser or VCSEL have the gain bandwidth of several nanometers, and in atomic clock long-term work process, the frequency of semiconductor laser or VCSEL can be drifted about, thereby influence the precision and the reliability of atomic clock.In addition, in order to improve the signal to noise ratio of CPT atomic clock, need allow the atom bubble be operated under the higher temperature, and VCSEL is operated in higher temperature following time, the life-span can shorten, thereby causes the lifetime of CPT atomic clock.
Summary of the invention
The invention provides a kind of CPT atomic clock and its implementation,, solve short problem of CPT atomic clock life-span in order to improve the precision and the reliability of CPT atomic clock in the prior art.
The invention provides a kind of CPT atomic clock implementation method, comprising:
Alkali metal gas electrodeless lamp optical filtering back is carried out pumping as pump light source to the alkali metal gas atom in the air chamber, realize that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect;
Described alkali metal gas laser is handled, through phase-locked acquisition double-frequency laser, perhaps obtained the n frequency laser through ovennodulation, n is the natural number more than or equal to 2;
Adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble is carried out laser pumping, according to the double-frequency laser of the phase-locked acquisition of described process, perhaps the n frequency laser that obtains through ovennodulation carries out the signal of the signal generation standard frequency of laser pumping generation to described alkali metal atom bubble.
The present invention also provides a kind of CPT atomic clock, comprising:
The alkali metal gas laser device is used for alkali metal gas electrodeless lamp is carried out pumping as pump light source to the alkali metal gas atom of air chamber, realizes that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect;
The alkali metal atom bubble;
The laser deriving means is used for the phase-locked acquisition double-frequency laser of described alkali metal gas laser process perhaps is used for described alkali metal gas is obtained the n frequency laser through ovennodulation, and n is the natural number more than or equal to 2;
Signal generating apparatus is used for according to the n frequency laser that will obtain through the double-frequency laser of phase-locked acquisition or through ovennodulation described alkali metal atom bubble being carried out the signal that signal that pumping produces generates standard frequency.
CPT atomic clock provided by the invention and its implementation, adopt the LASER Light Source of alkali metal laser as the CPT atomic clock, this alkali metal laser adopts alkali metal gas electrodeless lamp as pump light source, the light source of alkali metal gas electrodeless lamp emission filtered to satisfy in order to reach the pumping demand of one or more different wave lengths that the counter-rotating of layout number requires, the frequency stability and the pumping efficiency of pump light source have been guaranteed, need not the wavelength or the frequency of pump light source are carried out frequency stabilization control, therefore pump light source continuous operation for a long time, thereby strengthened the stability of the frequency of alkali metal laser, improved the precision and the reliability of CPT atomic clock.In addition, the alkali metal gas life-span as gain media among the present invention is long, even be operated under the higher temperature, the life-span of alkali metal laser also can reach 20 years, with respect to prior art, has increased the life-span of CPT atomic clock.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do one to the accompanying drawing of required use in embodiment or the description of the Prior Art below introduces simply, apparently, accompanying drawing in describing below is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Figure 1 shows that the flow chart of CPT atomic clock implementation method of the present invention;
Figure 2 shows that the alkali metal gas atomic energy level schematic diagram that relates in the various embodiments of the present invention;
Figure 3 shows that the rubidium atomic energy level structural representation that relates in the various embodiments of the present invention;
Figure 4 shows that the structural representation of CPT atomic clock of the present invention;
Figure 5 shows that the structural representation of CPT atomic clock embodiment one of the present invention;
Figure 6 shows that the structural representation of CPT atomic clock embodiment two of the present invention.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
Be illustrated in figure 1 as the flow chart of CPT atomic clock implementation method of the present invention, comprise:
Step 1011 adopts alkali metal gas electrodeless lamp to be created in first excited state and sends out alkali metal gas atom in the pump light pumping air chamber to transition spectral line between the ground state, so that the alkali metal gas atomic transition in the air chamber is to described first excited state, wherein, it is identical with alkali metal gas kind in the air chamber to fill alkali metal gas in the alkali metal gas electrodeless lamp.For example: with caesium electrodeless lamp pump caesium gas atom, or with rubidium electrodeless lamp pump rubidium gas atom.
Be illustrated in figure 2 as the alkali metal gas atomic energy level schematic diagram that relates in the various embodiments of the present invention, adopt alkali metal gas electrodeless lamp to be created in excitation state np
2P
3/2To ground state ns
2S
1/2Between transition pump light that spectral line is sent out with the alkali metal gas atomic excitation to excitation state np
2P
3/2Perhaps adopt alkali metal gas electrodeless lamp to be created in excitation state np
2P
1/2To ground state ns
2S
1/2Between transition pump light that spectral line is sent out with the alkali metal gas atomic excitation to excitation state np
2P
1/2Perhaps adopt alkali metal gas electrodeless lamp to be created in excitation state (n+1) p
2P
3/2To ground state ns
2S
1/2Between transition pump light that spectral line is sent out with the alkali metal gas atomic excitation to excitation state (n+1) p
2P
3/2Perhaps adopt alkali metal gas electrodeless lamp to be created in excitation state (n+1) p
2P
1/2To ground state ns
2S
1/2Between transition pump light that spectral line is sent out with the alkali metal gas atomic excitation to excitation state (n+1) p
2P
1/2
Step 1012, by other gas atoms that mix in the air chamber and/or the impact effect of the alkali metal gas atom in gas molecule and the air chamber, alkali metal gas atom in the air chamber migrates to second excitation state close with first excited state from first excited state, forms the layout number counter-rotating between second excitation state and the ground state.
In conjunction with shown in Figure 2, the alkali metal gas atom in the air chamber migrates to second excitation state close with described first excited state from first excited state, and the layout number counter-rotating that forms between second excitation state and the ground state specifically can be: excitation state np
2P
3/2The alkali metal gas atom transfer to excitation state np
2P
1/2Thereby, form excitation state np
2P
1/2With ground state ns
2S
1/2Between layout number counter-rotating; Perhaps excitation state np
2P
1/2The alkali metal gas atom transfer to excitation state np
2P
3/2Thereby, form excitation state np
2P
3/2With ground state ns
2S
1/2Between layout number counter-rotating; Perhaps excitation state (n+1) p
2P
3/2The alkali metal gas atom transfer to excitation state (n+1) p
2P
1/2Thereby, form excitation state (n+1) p
2P
1/2With ground state ns
2S
1/2Between layout number counter-rotating; Perhaps excitation state (n+1) p
2P
1/2The alkali metal gas atom transfer to excitation state (n+1) p
2P
3/2Thereby, form excitation state (n+1) p
2P
3/2With ground state ns
2S
1/2Between layout number counter-rotating.
In the embodiment of the invention, in the step 1012 in order to form excitation state np
2P
3/2With ground state ns
2S
1/2Between layout number counter-rotating, or form excitation state (n+1) p
2P
3/2With ground state ns
2S
1/2Between layout number counter-rotating, need to regulate the alkali metal gas electrodeless lamp that adopts and be created in excitation state np
2P
1/2Or (n+1) p
2P
1/2To ground state ns
2S
1/2Between the transition spectral line send out variant composition the intensity of spectral line in the pump light.For the caesium atom, can be with the ground state 6s in the caesium gas electrodeless lamp
2S
1/2Atom total angular momentum F=3 or the light filtering of the corresponding spectral line composition of F=4.For atomic weight is 87 rubidium atom, can be with the ground state 5s in the caesium gas electrodeless lamp
2S
1/2F=1 or the light filtering of the corresponding spectral line composition of F=2.
Step 1013, under the feedback effect of the residing resonant cavity of air chamber, export the alkali metal gas laser of second excitation state to transition spectral line respective frequencies between the ground state.
In conjunction with shown in Figure 2, frequency is corresponding excitation state np respectively
2P
1/2To ground state ns
2S
1/2Between transition spectral line or excitation state np
2P
3/2To ground state ns
2S
1/2Between transition spectral line or excitation state (n+1) p
2P
1/2To ground state ns
2S
1/2Between transition spectral line or excitation state (n+1) p
2P
3/2To ground state ns
2S
1/2Between the transition spectral line.
In embodiments of the present invention, be in the alkali metal gas atom in the air chamber in the resonant cavity and other gas atoms and/or the gas molecule of mixing and be referred to as gain media, no longer specifically statement of similar description is hereinafter arranged.Wherein, other gas atoms of mixing and/or gas molecule comprise the atom of quenching gas such as ethane or helium or the atom or the molecule of molecule and buffer gas (as argon, krypton, xenon etc.).
In method shown in Figure 1, can also be by the Q value of resonant cavity of control laser, make the chamber loft wide less than or greater than the laser gain live width, thereby regulate the live width of exporting laser; Can also control the length of the resonant cavity of laser, to regulate the output frequency of output laser.In addition, because gain media is a gas, the interaction between the atom of gas is less, and the resonant cavity of laser is longer, and the live width of output laser will obviously be narrower than the live width of the laser of ordinary semiconductor laser output.
Need to prove that alleged " first excited state " and " second excitation state close with first excited state " in various embodiments of the present invention is for convenience to the differentiation in the name of two adjoining excitation state.Promptly in embodiments of the present invention, if first excited state is (n+1) p
2P
1/2, second excitation state is (n+1) p so
2P
3/2If first excited state is np
2P
3/2, second excitation state is np so
2P
1/2
With alkali metal is that rubidium is an example, is illustrated in figure 3 as the rubidium atomic energy level structural representation that relates in the various embodiments of the present invention, and two frequencies of laser correspond respectively to the 5s of rubidium atom
2S
1/2The F=1 attitude is to 5p
2P
1/2The jump frequency of F=1 attitude and 5s
2S
1/2The F=2 attitude is to 5p
2P
1/2The jump frequency of F=1 attitude.Perhaps, two of laser frequencies correspond respectively to the 5s of rubidium atom
2S
1/2The F=1 attitude is to 5p
2P
1/2The jump frequency of F=2 attitude and 5s
2S
1/2The F=2 attitude is to 5p
2P
1/2The jump frequency of F=2 attitude.
Perhaps, step 102 can be carried out the phase-locked back acquisition of bimodulus double-frequency laser to alkali metal gas laser.For example, can adopt the Phase Lock Technique in the laser technology field to carry out the phase-locked back acquisition of bimodulus double-frequency laser.The difference on the frequency of double-frequency laser can be measured by quick photoelectric detector, and the difference on the frequency of double-frequency laser can be by the long control in the chamber of laserresonator.
In the step 103, with the alkali metal atom bubble being carried out laser pumping through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation, two sub-energy levels of clock transition of alkali metal atom ground state are by under two coherent laser field couplings, alkali metal atom is coherently imprisoned in the dark attitude of quantum that two sub-energy levels are formed, and no longer absorbs photon.
The CPT atomic clock can comprise active CPT atomic clock and passive-type CPT atomic clock.For active CPT atomic clock, the alkali metal atom bubble is arranged in the microwave cavity, be filled with required buffer gas in the alkali metal atom bubble, the alkali metal atom bubble can also be arranged in the D.C. magnetic field (in this area so-called C field), alkali metal gas atom bubble also periphery can also be provided with magnetic screen and temperature control equipment, and the alkali metal atom when being in coherent layout number imprison attitude is exported under the coupling of microwave cavity as the relevant sharp microwave of penetrating.
For active CPT atomic clock, step 103 can comprise: adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble that is arranged in the microwave cavity is carried out pumping, produce microwave signal; To adopt the n frequency laser that obtains through the double-frequency laser of phase-locked acquisition or through ovennodulation to carry out the microwave signal that pumping produces and compare the generation error signal with the microwave signal of microwave source to being arranged on alkali metal atom bubble in the microwave cavity; Produce control signal according to error signal, control signal is sent to crystal oscillator, make crystal oscillator generate the signal of standard frequency, and the signal of the standard frequency that generates according to crystal oscillator generates the signal that is used to drive electrooptic modulator.
For passive-type CPT atomic clock, the alkali metal atom bubble does not need to be arranged in the microwave cavity, directly the alkali metal atom bubble is carried out pumping generation light signal through the double-frequency laser of phase-locked acquisition or through the n frequency laser that ovennodulation obtains.
For passive-type CPT atomic clock, step 103 can comprise: adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble is carried out pumping, produce light signal; Adopt photodetector to receive the alkali metal atom bubble is carried out the light signal that pumping produced, and convert the light signal that receives to the signal of telecommunication through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation; The signal of telecommunication that converts to according to photodetector generates control signal, and control signal is sent to crystal oscillator, makes crystal oscillator generate the signal of standard frequency, and the signal of the standard frequency that generates according to crystal oscillator generates the signal that is used to drive described electrooptic modulator.
The CPT atomic clock implementation method that present embodiment provides, adopt the LASER Light Source of alkali metal laser as the CPT atomic clock, this alkali metal laser adopts alkali metal gas electrodeless lamp as pump light source, the light source of alkali metal gas electrodeless lamp emission is carried out rate light can be satisfied in order to reach the pumping demand of one or more different wave lengths that the counter-rotating of layout number requires, the frequency stability and the pumping efficiency of pump light source have been guaranteed, need not the wavelength or the frequency of pump light source are carried out frequency stabilization control, therefore pump light source continuous operation for a long time, thereby strengthened the stability of the frequency of alkali metal laser, improved the precision and the reliability of CPT atomic clock.In addition, the alkali metal gas life-span as gain media among the present invention is long, even be operated under the higher temperature, the life-span of alkali metal laser also can reach 20 years, with respect to prior art, has increased the life-span of CPT atomic clock.
Be illustrated in figure 4 as the structural representation of CPT atomic clock of the present invention, this CPT atomic clock comprises alkali metal gas laser device 11, alkali metal atom bubble 12, laser deriving means 13 and signal generating apparatus 14.Alkali metal gas laser device 11 is used for alkali metal gas electrodeless lamp is carried out pumping as pump light source to the alkali metal gas atom of air chamber, realizes that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect.Alkali metal atom bubble 12 can be the bubble that is filled with alkali metal gas that a glass is made.The alkali metal gas laser that laser deriving means 13 is used for alkali metal gas laser device 11 is formed perhaps is used for alkali metal gas is obtained the n frequency laser through ovennodulation through phase-locked acquisition double-frequency laser.Signal generating apparatus is used for the double-frequency laser through phase-locked acquisition, and perhaps the n frequency laser that obtains through ovennodulation carries out the signal of the signal generation standard frequency of pumping generation to the alkali metal atom bubble.
Wherein, the alkali metal gas laser device can comprise alkali metal gas electrodeless lamp 111, filtering apparatus 112 and the condenser lens 113 that sets gradually, and is used to be created in the pump light source of first excited state to transition spectral line between the ground state.Also comprise the laserresonator of being with piezoelectric ceramic 114, an end of this laserresonator is provided with the high anti-pump light diaphotoscope 115 of laser near condenser lens 113 1 sides, and the other end of laserresonator is provided with coupled lens 116 near piezoelectric ceramic 114 1 sides.Also comprise the air chamber 117 that is arranged in the laserresonator, be filled with in the air chamber 117 and alkali metal gas electrodeless lamp 111 interior identical alkali metal gas, and be mixed be used for air chamber 117 in other gas atoms and/or the gas molecule of alkali metal gas atomic collision, form alkali metal gas laser.
Wherein, the laser deriving means can be electrooptic modulator or bimodulus phase-locking device.
Be illustrated in figure 5 as the structural representation of CPT atomic clock embodiment one of the present invention, this CPT atomic clock is a kind of active CPT atomic clock, the CPT atomic clock that this embodiment provides is on the basis of as shown in Figure 4 CPT atomic clock, also comprise isolator 15, spectroscope 16, speculum 17, quarter-wave plate 18 and alkali metal atom spectrum frequency stabilization system 22, signal generating apparatus comprises microwave cavity 141, microwave source 142, first control module 143 and the crystal oscillator 144 that is arranged on alkali metal atom bubble 12 outsides.Isolator 15 and spectroscope 16 are successively set between piezoelectric ceramic 114 and the laser deriving means, the laser deriving means is an electrooptic modulator 23 in the present embodiment, the road light signal of telling from spectroscope 16 is input to alkali metal atom spectrum frequency stabilization system 22, alkali metal atom spectrum frequency stabilization system 22 outputs signal to piezoelectric ceramic 114, chamber by piezoelectric ceramic 114 control resonant cavitys is long, thus the frequency of the laser of stabilized lasers resonant cavity output.Speculum 17 and quarter-wave plate 18 are successively set between electrooptic modulator 23 and the microwave cavity 141.Alkali metal atom bubble 12 is arranged on microwave cavity 141 inside.Wherein, microwave source 142 signal that is used for the standard frequency that generates according to crystal oscillator 144 generates the signal that is used to drive electrooptic modulator 23.First control module 143 is used for the microwave signal of microwave cavity 141 outputs is compared with the microwave signal of microwave source 142 outputs, produce error signal, and, control signal is sent to crystal oscillator 144 according to error signal generation control signal, make crystal oscillator 144 produce the signal of standard frequencies.
Among Fig. 5, the outside of microwave cavity 141 can also be provided with C field coil 24, temperature control equipment 25 and magnetic shielding device 26.
The operation principle of this active CPT atomic clock is: the light that alkali metal gas electrodeless lamp 111 generations are sent is electro-optical device 112 and the condenser lens 113 back pump light sources that produce first excited states to the transition spectral line between the ground state after filtration, gain media in this pump light source and the laserresonator in the air chamber 117 interacts, and forms alkali metal laser.Two glass end faces of air chamber 117 can plate the loss that anti-reflection film lowers pump light source and laser.With alkali metal is that rubidium is an example, through the D of the 780.0nm after filtering
2Spectral line is as pump light source, and rubidium atom bubble is energized into D by pump light source
2The excitation state of spectral line, i.e. 5p
2P
3/2Attitude, by the ethane and the helium effect that mix in the air chamber 117, these are excited to D
2The atom transfer of the excitation state of spectral line is to 5p
2P
1/2Attitude, just D
1The excitation state of spectral line has formed D
1The excitation state of spectral line and the counter-rotating of the atom layout number between the ground state.Under the feedback of laserresonator, form near the D of 794.8nm wavelength
1The laser output of spectral line, the adjusting long by the laserresonator chamber is locked in D with laser frequency on the rubidium atomic spectra
15s in the spectral line
2S
1/2, the F=1 energy level is to 5p
2P
1/2, on the frequency of F '=2 energy level correspondences.
Alkali metal laser is by isolator 15 and spectroscope 16, and a part of laser is input to electrooptic modulator 23, and a part of laser is input to alkali metal atom spectrum frequency stabilization system 22.Alkali metal atom spectrum frequency stabilization system 22 produces the piezoelectric ceramic control signal according to the laser of input, the piezoelectric ceramic control signal sends to piezoelectric ceramic 114, the chamber that can control laserresonator by piezoelectric ceramic 114 is long, thus the frequency of the alkali metal laser of control output.The laser of 23 pairs of inputs of electrooptic modulator is modulated the back and is produced the n frequency laser, and laser forms circularly polarized light through speculum 17 and quarter-wave plate 18 backs.
Circularly polarized light carries out pumping to alkali metal atom bubble 12, and microwave cavity 141 carries out the signal reflex that pumping produces with circularly polarized light to alkali metal atom bubble 12, forms standing wave, the relevant microwave signal of output.
As can be seen from Figure 5, first control module 143 is by the frequency of the signal of generated error signal controlling crystal oscillator 144 generations, and the generation of error signal depends on the microwave signal of the signal formation that the interaction of n frequency laser that microwave signal that microwave source generates and electrooptic modulator 23 produce and alkali metal atom bubble produces, the generation that is to say error signal depends on the microwave signal of microwave source and the frequency of the laser that electrooptic modulator generates, this is actually and has formed a closed-loop control, makes the signal of crystal oscillator output can be stabilized in standard frequency.
Be illustrated in figure 6 as the structural representation of CPT atomic clock embodiment two of the present invention, the CPT atomic clock that this CPT atomic clock is a kind of passive-type, the signal generating apparatus 14 of this CPT atomic clock comprise photodetector 145, microwave source 142, second control module 146 and crystal oscillator 144.Wherein, photodetector 145 is used for the light signal that the alkali metal atom bubble carries out the pumping generation being converted the n frequency laser to the signal of telecommunication.The signal of telecommunication that second control module 146 is used for converting to according to photodetector 145 generates control signal, and control signal is sent to crystal oscillator 144, makes crystal oscillator 144 generate the signal of standard frequency.
The main distinction part of CPT atomic clock shown in Figure 6 and CPT atomic clock shown in Figure 5 is: among Fig. 6, do not comprise microwave cavity 141, and among Fig. 5, signal generating apparatus comprises microwave cavity 141.Comprise among Fig. 6 that photodetector 145, the second control modules 146 produce control signal according to the signal of telecommunication that photodetector 145 generates; And among Fig. 5, do not comprise that photodetector 145, the first control modules 143 generate control signal according to the error signal of microwave source 142 and microwave cavity 141 generations.
This passive-type CPT atomic clock and the lasing operation principle of active CPT atomic clock are basic identical, and the difference part is that passive-type CPT atomic clock is different with the principle of the standard frequency of active CPT atomic clock adjustment output.
Passive-type CPT atomic clock does not have microwave cavity 141, adopt the n frequency laser that the light signal that alkali metal atom bubble 12 carries out the pumping generation is converted to the signal of telecommunication through behind the photodetector 145, second control module 146 generates control signal according to the signal of telecommunication that photodetector 145 converts to, control signal is sent to crystal oscillator, make crystal oscillator generate the signal of standard frequency.In addition, microwave source 142 generates the signal that is used to drive electrooptic modulator 23 according to the signal of the standard frequency of crystal oscillator 144 generations.
In passive-type CPT atomic clock, photodetector 145 detects and is actually a kind of fluorescent line signal, the bright line signal that comprises resonance concealed wire or transmitted light, detected fluorescent line signal is relevant with the off resonance of clock jump frequency, and second control module 146 generates control signal according to this fluorescent line signal.
Among Fig. 6, in case the signal generation deviation that photodetector detects, then second control module can be controlled the frequency of crystal oscillator output, and can control the frequency of the n frequency laser of electrooptic modulator generation according to the signal of crystal oscillator output, and then the signal that makes photodetector detect levels off to echo signal, in fact also is to have formed a kind of closed-loop control.
Passive-type CPT atomic clock is not owing to need microwave cavity, and therefore whole structure can miniaturization and microminiaturization, in conjunction with microelectromechanical systems (Micro-Electro-Mechanical Systems is called for short MEMS), can make chip-shaped CPT atomic clock.
Be to be that electrooptic modulator is that example is introduced among Fig. 5 and Fig. 6 with the laser deriving means, if the laser deriving means is the bimodulus phase-locking device, then also can control the frequency of laser of the double frequency of bimodulus phase-locking device output as feedback signal according to the interact signal that produces of double-frequency laser and alkali metal atom bubble.Can adopt some control technologys to realize particularly.
CPT atomic clock provided by the invention, adopt the LASER Light Source of alkali metal laser as the CPT atomic clock, this alkali metal laser adopts alkali metal gas electrodeless lamp as pump light source, the light source of alkali metal gas electrodeless lamp emission filtered to satisfy in order to reach the pumping demand of one or more different wave lengths that the counter-rotating of layout number requires, the frequency stability and the pumping efficiency of pump light source have been guaranteed, need not the wavelength or the frequency of pump light source are carried out frequency stabilization control, therefore pump light source continuous operation for a long time, thus the stability of the frequency of alkali metal laser strengthened.In addition, the alkali metal gas life-span as gain media among the present invention is long, even be operated under the higher temperature, the life-span of alkali metal laser also can reach 20 years, with respect to prior art, increased the life-span of CPT atomic clock, improved the precision and the reliability of CPT atomic clock.
It should be noted that at last: above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the spirit and scope of various embodiments of the present invention technical scheme.
Claims (4)
1. a coherent layout number imprison atomic clock implementation method is characterized in that, comprising:
Alkali metal gas electrodeless lamp optical filtering back is carried out pumping as pump light source to the alkali metal gas atom in the air chamber, realize that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect;
Described alkali metal gas laser is handled, through phase-locked acquisition double-frequency laser, perhaps obtained the n frequency laser through ovennodulation, n is the natural number more than or equal to 2;
Adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble is carried out laser pumping, described alkali metal atom bubble is carried out the signal that signal that laser pumping produces generates standard frequency according to the n frequency laser that obtains through the double-frequency laser of phase-locked acquisition or through ovennodulation;
The phase-locked acquisition double-frequency laser of described process perhaps obtains the n frequency laser through ovennodulation, comprising:
Adopt electrooptic modulator that described alkali metal gas laser modulation back is obtained the n frequency laser; Perhaps
Described alkali metal gas laser is carried out the phase-locked back of bimodulus obtain double-frequency laser;
Described employing is carried out laser pumping through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation to the alkali metal atom bubble, according to the n frequency laser that obtains through the double-frequency laser of phase-locked acquisition or through ovennodulation described alkali metal atom bubble is carried out the signal that signal that laser pumping produces generates standard frequency, comprising:
Adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble that is arranged in the microwave cavity is carried out pumping, produce microwave signal;
To adopt the n frequency laser that obtains through the double-frequency laser of phase-locked acquisition or through ovennodulation to carry out the microwave signal that pumping produces and compare the generation error signal with the microwave signal of microwave source to being arranged on alkali metal atom bubble in the microwave cavity;
Produce control signal according to described error signal, described control signal is sent to crystal oscillator, make crystal oscillator generate the signal of standard frequency, and the signal of the standard frequency that generates according to described crystal oscillator generates the signal that is used to drive described electrooptic modulator;
Perhaps, described employing is carried out laser pumping through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation to the alkali metal atom bubble, according to the n frequency laser that obtains through the double-frequency laser of phase-locked acquisition or through ovennodulation described alkali metal atom bubble is carried out the signal that signal that laser pumping produces generates standard frequency, comprising:
Adopt through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation the alkali metal atom bubble is carried out pumping, produce light signal;
Adopt photodetector to receive the alkali metal atom bubble is carried out the light signal that pumping produced, and convert the light signal that receives to the signal of telecommunication through the double-frequency laser of phase-locked acquisition or the n frequency laser that obtains through ovennodulation;
The signal of telecommunication that converts to according to photodetector generates described control signal, described control signal is sent to crystal oscillator, make crystal oscillator generate the signal of standard frequency, and the signal of the standard frequency that generates according to described crystal oscillator generate the signal that is used to drive described electrooptic modulator.
2. method according to claim 1, it is characterized in that, the described back of will alkali metal gas electrodeless lamp filtering be carried out pumping as pump light source to the alkali metal gas atom in the air chamber, realize that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect, comprising:
Adopt alkali metal gas electrodeless lamp to be created in first excited state and send out alkali metal gas atom in the pump light pumping air chamber to transition spectral line between the ground state, so that the described alkali metal gas atomic transition in the described air chamber is to described first excited state, wherein, it is identical with alkali metal gas kind in the described air chamber to fill alkali metal gas in the described alkali metal gas electrodeless lamp;
By other gas atoms that mix in the described air chamber and/or the impact effect of the described alkali metal gas atom in gas molecule and the described air chamber, described alkali metal gas atom in the described air chamber migrates to second excitation state close with described first excited state from described first excited state, forms the layout number counter-rotating between described second excitation state and the ground state;
Under the feedback effect of the residing resonant cavity of described air chamber, export the alkali metal gas laser of described second excitation state to transition spectral line respective frequencies between the described ground state.
3. a coherent layout number imprison atomic clock is characterized in that, comprising:
The alkali metal gas laser device is used for alkali metal gas electrodeless lamp is carried out pumping as pump light source to the alkali metal gas atom of air chamber, realizes that layout number counter-rotating back forms alkali metal gas laser under the laserresonator effect;
The alkali metal atom bubble;
The laser deriving means is used for the phase-locked acquisition double-frequency laser of described alkali metal gas laser process perhaps is used for described alkali metal gas is obtained the n frequency laser through ovennodulation, and n is the natural number more than or equal to 2;
Signal generating apparatus is used for according to the n frequency laser that will obtain through the double-frequency laser of phase-locked acquisition or through ovennodulation described alkali metal atom bubble being carried out the signal that signal that pumping produces generates standard frequency;
Described laser deriving means is electrooptic modulator or bimodulus phase-locking device;
Described signal generating apparatus comprises: the microwave cavity, microwave source, first control module and the crystal oscillator that are arranged on alkali metal atom bubble outside;
Described microwave source is used for generating the signal that is used to drive described electrooptic modulator according to the signal of the standard frequency of described crystal oscillator generation;
Described first control module is used for the microwave signal of described microwave cavity output is compared with the microwave signal of described microwave source output, produce error signal, and, described control signal is sent to crystal oscillator according to described error signal generation control signal, make crystal oscillator produce the signal of standard frequency;
Perhaps, described signal generating apparatus comprises photodetector, described microwave source, second control module and described crystal oscillator:
Described microwave source is used for generating the signal that is used to drive described electrooptic modulator according to the signal of the standard frequency of described crystal oscillator generation;
Described photodetector is used for and will the light signal that the alkali metal atom bubble carries out the pumping generation be converted to the signal of telecommunication through the phase-locked double-frequency laser that obtains or through the n frequency laser that ovennodulation is obtained;
The signal of telecommunication that described second control module is used for converting to according to described photodetector generates control signal, and described control signal is sent to crystal oscillator, makes described crystal oscillator generate the signal of standard frequency.
4. coherent layout number imprison atomic clock according to claim 3 is characterized in that described alkali metal gas laser device comprises:
The alkali metal gas electrodeless lamp that sets gradually, filtering apparatus and condenser lens are used to be created in the pump light source of first excited state to transition spectral line between the ground state;
The laserresonator of band piezoelectric ceramic, an end of described laserresonator is provided with the high anti-pump light diaphotoscope of laser near described condenser lens one side, and the other end of described laserresonator is provided with coupled lens near piezoelectric ceramic one side;
Be arranged at the air chamber in the described laserresonator, be filled with in the described air chamber with described alkali metal gas electrodeless lamp in identical alkali metal gas, and be mixed be used for described air chamber in other gas atoms and/or the gas molecule of alkali metal gas atomic collision, form alkali metal gas laser.
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| CN103414470B (en) * | 2013-07-29 | 2016-01-20 | 北京大学 | The active light clock production method that gain media is separated with quantum reference medium and device |
| CN103856215A (en) * | 2014-03-03 | 2014-06-11 | 苏州大学 | Low-power-consumption chip level atomic clock physical packaging device |
| CN105577188B (en) * | 2015-12-17 | 2018-09-07 | 北京无线电计量测试研究所 | A kind of method and device for realizing CPT atomic frequency standards |
| CN105811972B (en) * | 2016-03-11 | 2019-02-22 | 清华大学 | A kind of pulsed coherent layout Trapping of Atoms clock magnetic field servo-system |
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| CN107064826B (en) * | 2017-05-18 | 2019-11-08 | 北京航空航天大学 | A kind of nonmagnetic atom microscopic method based on chamber resonance and magnetic aggregated structure |
| CN107579409B (en) * | 2017-09-22 | 2019-06-18 | 合肥工业大学 | A kind of bright squeezed type light field generator |
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