CN103955130A - Differential detection device and method for coherent layout imprisoned magneto-optic effect - Google Patents
Differential detection device and method for coherent layout imprisoned magneto-optic effect Download PDFInfo
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- CN103955130A CN103955130A CN201410197736.2A CN201410197736A CN103955130A CN 103955130 A CN103955130 A CN 103955130A CN 201410197736 A CN201410197736 A CN 201410197736A CN 103955130 A CN103955130 A CN 103955130A
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Abstract
The invention discloses a differential detection device for a coherent layout imprisoned magneto-optic effect. The differential detection device comprises a bias coupler, a laser, a solenoid, alkali metal atomic vapor bubbles, a polarization beam splitting crystal, a photoelectric cell and a second photoelectric cell. The invention also discloses a differential detection method for the coherent layout imprisoned magneto-optic effect. According to the method, differential detection is performed on a laser signal obtained after linearly polarized light and atoms are mutually interacted in a magnetic field; through the scheme, common-mode noises which are associated with laser amplitude noises and frequency noises can be inhibited, so that the signal-to-noise ratio of the signal is improved; therefore, the stability of the output frequency of a coherent layout imprisoned atomic clock is improved. A passive coherent layout imprisoned atomic clock realized by adopting the scheme has the advantages of simple structure, low cost, small size and the like, and is suitable for realizing small and micro atomic clocks. The invention also discloses the differential detection method for the coherent layout imprisoned magneto-optic effect.
Description
Technical field
The present invention relates to passive-type coherent layout Trapping of Atoms clock field, relate in particular to the difference detecting device of coherent layout imprison magneto-optic effect, also relate to the difference detecting method of coherent layout imprison magneto-optic effect.
Background technology
Passive-type coherent layout Trapping of Atoms clock is a kind of electronics equipment of exporting highly stable frequency signal, have volume little, low in energy consumption, lightweight, start the various features such as fast and Miniaturized, can be applicable to the technical fields such as satellite navigation, location, Geological Engineering measurement, communication, missile guidance and electronics equipment equipment.
The principle of work of passive-type coherent layout Trapping of Atoms clock is: the laser of two different frequencies (two-color laser) field and the Three-level Atom system effect being comprised of an excited level and the hyperfine energy level of two ground state, when two frequencies of two-color laser meet respectively the frequency from a ground state to excited state transition, and the difference of two frequencies strictly equals the resonant frequency of the hyperfine energy of two ground state of atom inter-stage, two-color laser field just can resonate with the imprison of atoms at suitable temperatures coherent layout, two ground state of atom are prepared into coherent superposition state, i.e. coherent layout imprison state.Atom in coherent layout imprison state no longer absorbs energy from laser field, therefore when the two-color laser bundle through atomic medium meets coherent layout imprison resonant condition transmitted light than the light intensity that does not meet resonant condition (electromagnetically induced Transparency Phenomenon) more by force.Passive-type coherent layout Trapping of Atoms clock is locked in the output frequency of atomic clock on the resonant frequency of the hyperfine energy of atom two ground state inter-stage as frequency discrimination signal by surveying transmission laser light intensity, utilize the electromagnetically induced transparent signal obtaining.
The scheme of the passive-type coherent layout Trapping of Atoms clock of current trend is that the laser beam that laser tube produces realizes coherent layout imprison resonance by the interior atomic gas of atom steam bubble and bubble, and photodetector is surveyed transmission laser bundle and obtained photosignal.In the photosignal that detector obtains, comprised the needed coherent layout imprison of locking atomic clock output frequency signal.In addition, in the signal detecting, also comprise the absorption signal of atom pair single photon, and the laser frequency composition that does not participate in atom effect, the noise that these signals are corresponding comprises: 1, laser power noise; 2, the absorption signal amplitude noise that laser frequency noise changes into by atom pair laser absorption; 3, the fluctuating of the atomicity density of steam bubble causes gradual amplitude noise that the absorption of atom pair laser changes etc.The slowly time-varying noise that light absorption is changed that the noise that these are associated with laser amplitude noise and frequency noise and atomicity density fluctuation cause has affected the signal to noise ratio (S/N ratio) of coherent layout imprison signal, thereby affects the frequency stability of passive-type coherent layout Trapping of Atoms clock.
The invention provides and a kind ofly by difference detecting, suppress noise and improve the device and method that institute's coherent layout that obtains is imprisoned Signal-to-Noise.
Summary of the invention
The principle of linearly polarized light coherent layout imprison Magneto-optic Rotation is: in magnetic field environment, left-handed and the right-handed rotation component of linearly polarized light has experienced different dispersions and absorption when from alkali metal atom coherent layout imprison resonance, and laser is through rotating polarization direction afterwards with the effect of bubble Atom.
After atom steam bubble, place a polarization beam splitting crystal, when the transmission polarization direction of polarization beam splitting crystal and the polarization direction angle of incident ray polarized light are 45 °, the absorption signal of atom pair single photon and the polarization that does not participate in the laser frequency composition of atom effect do not change, be polarized the two bundle laser that beam splitting crystal minute success ratio equates, when linearly polarized light coherent layout imprison Magneto-optic Rotation effect is carried out to difference detecting, these signals are cancelled out each other, and the Magneto-optic Rotation signal that polarization has occurred to rotate can be extracted, therefore in principle, can greatly reduce the slowly time-varying noise that light absorption is changed that the noise that is associated with laser amplitude noise and frequency noise and atomicity density fluctuation cause.In addition, parallel lines polarized light and alkali metal atom are done the used time except the Magneto-optic Rotation effect of coherent layout imprison resonance, also have the Magneto-optic Rotation effect of alkali metal atom to single-photon transition.When magnetic field is the magnitude of tens μ T in theory, under the condition of work of passive-type coherent layout Trapping of Atoms clock, little 3 magnitudes of Magneto-optic Rotation signal amplitude that alkali metal atom resonates than coherent layout imprison to the Magneto-optic Rotation signal amplitude of single-photon transition, and the Magneto-optic Rotation signal of single-photon transition is Doppler broadening, the Magneto-optic Rotation effect of signals of the linearly polarized light coherent layout imprison that therefore the Magneto-optic Rotation signal of single-photon transition obtains us can be ignored, the Magneto-optic Rotation signal that we experimentally detect is mainly derived from linearly polarized light and alkali-metal coherent layout imprison resonance.
The difference detecting device that the object of this invention is to provide a kind of coherent layout imprison magneto-optic effect, temperature, drive current, input microwave power that this device not only can suppress laser tube change the laser power noise causing, can also suppress laser frequency noise composes by Atomic absorption the amplitude noise and the steam bubble temperature variation that are transformed and causes the noise to laser absorption, thereby improve the signal to noise ratio (S/N ratio) of coherent layout imprison signal, and then improve the degree of stability of passive-type coherent layout Trapping of Atoms clock output frequency.And this apparatus structure is simple, cost is low, volume is little, be applicable to small-sized and miniature atomic clock.
To achieve these goals, the invention provides a kind of difference detecting device of coherent layout imprison magneto-optic effect, device comprises the biasing coupling mechanism that microwave signal and direct current signal is coupled into modulation signal, the laser tube being driven by modulation signal, alkali metal atom steam bubble, polarization beam splitting crystal and the first photoelectric cell that the exit direction of the laser beam of launching along laser tube sets gradually, reflection direction at polarization beam splitting crystal is provided with the second photoelectric cell, and alkali metal atom steam bubble is placed in solenoid.Buffer gas in atom steam bubble is inert gas, and pressure is 3-5Torr, and temperature is controlled at 40-60 ° of C, and alkali metal atom steam bubble provides the 5-15 μ axial magnetic field of T by solenoid, and solenoid outermost layer carries out magnetic shielding with the material of high magnetic permeability.45 ° of the transmission polarization direction angles of the laser polarization direction that laser tube sends and polarization beam splitting crystal, transmitted light is polarized beam splitting crystal and is divided into two bundles that power equates.The first photoelectric cell is arranged on the transmission direction of polarization beam splitting crystal, and the second photoelectric cell is arranged on the reflection direction of polarization beam splitting crystal.
Correspondingly, the present invention also provides a kind of difference detecting method of coherent layout imprison magneto-optic effect, comprising:
Step 1, microwave signal and direct current signal intercouple by biasing coupling mechanism, and the signal driver laser tube after coupling sends polychrome frequency modulation linearly polarized light;
Step 2, in the magnetic field environment of 5-15uT, in polychrome frequency modulation linearly polarized laser bundle and alkali metal atom steam bubble, alkali metal atom effect obtains Magneto-optic Rotation effect;
Step 3, that the laser beam through alkali metal atom steam bubble is divided into polarization is mutually vertical, two bundles that power equates;
Step 4, survey respectively the luminous power of two bundle laser, the optical power signals of two bundle laser is subtracted each other, obtain the Magneto-optic Rotation signal of linearly polarized light coherent layout imprison.
The difference detecting device of coherent layout imprison magneto-optic effect is with respect to the passive-type coherent layout Trapping of Atoms clock scheme of current trend, and volume, power consumption and cost all remain unchanged substantially, can be applied to small-sized, miniature passive-type coherent layout Trapping of Atoms clock.
By following description also by reference to the accompanying drawings, it is more clear that the present invention will become, and these accompanying drawings are used for explaining embodiments of the invention.
Accompanying drawing explanation
Fig. 1 is the structural representation of apparatus of the present invention.
Fig. 2 is the noise spectrum of differential signal and the contrast of the noise spectrum of single photoelectric cell signal that apparatus of the present invention produce.
Fig. 3 is the process flow diagram of the inventive method.
In figure: the 1-coupling mechanism of setovering; 2-laser tube; 3-alkali metal atom steam bubble; 4-polarization beam splitting crystal; 5-the first photoelectric cell; 6-the second photoelectric cell; 7-solenoid.
Embodiment
With reference now to accompanying drawing, describe embodiments of the invention, in accompanying drawing, similarly element numbers represents similar element.
As shown in Figure 1, by microwave signal and direct current signal, pass through biasing coupling mechanism 1, the frequency range of biasing coupling mechanism work should comprise the micro-wave frequency of input, the modulation signal driving laser pipe 2 being coupled into, the exit direction of the laser beam of launching along laser tube sets gradually alkali metal atom steam bubble 3, polarization beam splitting crystal 4, the first photoelectric cell 5, the second photoelectric cells 6 that are placed in solenoid 7.45 ° of the transmission polarization direction angles of the laser polarization direction that laser tube 2 sends and polarization beam splitting crystal 4, two bundles that minute success ratio equates are that the polarization angle by regulating laser tube to send laser guarantees.The first photoelectric cell 5 is arranged on the transmission direction of polarization beam splitting crystal, and the second photoelectric cell 6 is arranged on the reflection direction of polarization beam splitting crystal 4, and the first photoelectric cell 5 and the second photoelectric cell 6 can be selected the S-25VL photoelectric cell of OSI Optoelectronics company.The alkali metal atom steam bubble 3 being placed in solenoid needs solenoid 7 that the axial magnetic field of 5-15uT is provided, and outermost layer need to carry out with the material of high magnetic permeability the impact that magnetic shielding reduces stray magnetic field, and the material of high magnetic permeability can adopt not alloy of glass.Buffer gas in atom steam bubble is selected inert gas or nitrogen, and pressure should be 3-5Torr, and temperature is controlled at 40-60 ° of C
Particularly, the polychrome linearly polarized light that the laser tube 2 that the modulation signal being coupled into by biasing coupling mechanism 1 by microwave signal and direct current signal drives sends and atomic interaction are prepared coherent layout imprison state, under the axial magnetic field environment providing at solenoid, due to Magneto-optic Rotation effect, the left-handed and right hand component of linearly polarized light is experiencing different dispersions and absorption from atom as the used time.After vapour of an alkali metal bubble 3, laser beam is polarized beam splitting crystal 4 and is divided into the two bundle laser that power is close, is surveyed respectively by the first photoelectric cell 5 and the second photoelectric cell 6, and detectable signal subtracts each other can obtain linearly polarized light coherent layout imprison Magneto-optic Rotation signal.
Fig. 2 is the noise spectrum of differential signal and the contrast of the noise spectrum of single photoelectric cell signal that apparatus of the present invention produce.The line of grey is the noise spectrum of single photoelectric cell signal, the line of black is the noise spectrum of the differential signal of device generation, the former squelch of noise ratio frequency range the latter of 0.1Hz-1kHz surpasses 20dB, prove that the present invention can suppress the slowly time-varying noise to light absorption variation that the noise that is associated with laser amplitude noise and frequency noise and atomicity density fluctuation cause really.
Fig. 3 is the process flow diagram of the inventive method.
The difference detecting method of coherent layout imprison magneto-optic effect of the present invention comprises the steps:
Step 1, microwave signal and direct current signal intercouple by biasing coupling mechanism, and the signal driver laser tube after coupling sends polychrome frequency modulation linearly polarized light;
Step 2, in the magnetic field environment of 5-15uT, in polychrome frequency modulation linearly polarized laser bundle and alkali metal atom steam bubble, alkali metal atom effect obtains Magneto-optic Rotation effect;
Step 3, that the laser beam through alkali metal atom steam bubble is divided into polarization is mutually vertical, two bundles that power equates;
Step 4, survey respectively the luminous power of two bundle laser, the optical power signals of two bundle laser is subtracted each other, obtain the Magneto-optic Rotation signal of linearly polarized light coherent layout imprison.
Invention has been described for above combination most preferred embodiment, but the present invention is not limited to the embodiment of above announcement, and should contain the various modifications of carrying out according to essence of the present invention, equivalent combinations.
Claims (5)
1. coherent layout is imprisoned the difference detecting device of magneto-optic effect, it is characterized in that, comprise the biasing coupling mechanism that microwave signal and direct current signal is coupled into modulation signal, the laser tube being driven by modulation signal, alkali metal atom steam bubble, polarization beam splitting crystal and the first photoelectric cell that the exit direction of the laser beam of launching along laser tube sets gradually, reflection direction at polarization beam splitting crystal is provided with the second photoelectric cell, and alkali metal atom steam bubble is placed in solenoid.
2. the difference detecting device of coherent layout imprison magneto-optic effect according to claim 1, is characterized in that 45 ° of the transmission polarization direction angles of the laser polarization direction that described laser tube sends and polarization beam splitting crystal.
3. coherent layout according to claim 1 is imprisoned the difference detecting device of magneto-optic effect, it is characterized in that, the buffer gas arranging in described alkali metal atom steam bubble is inert gas, pressure is 3-5Torr, temperature is controlled at 40-60 ° of C, alkali metal atom steam bubble provides the 5-15 μ axial magnetic field of T by solenoid, and solenoid outermost layer carries out magnetic shielding with the material of high magnetic permeability.
4. utilize device described in claim 1 to carry out the difference detecting method of coherent layout imprison magneto-optic effect, comprising:
Step 1, microwave signal and direct current signal intercouple by biasing coupling mechanism, and the signal driver laser tube after coupling sends polychrome frequency modulation linearly polarized light;
Step 2, in the magnetic field environment of 5-15uT, in polychrome frequency modulation linearly polarized laser bundle and alkali metal atom steam bubble, alkali metal atom effect obtains Magneto-optic Rotation effect;
Step 3, that the laser beam through alkali metal atom steam bubble is divided into polarization is mutually vertical, two bundles that power equates;
Step 4, survey respectively the luminous power of two bundle laser, the optical power signals of two bundle laser is subtracted each other, obtain the Magneto-optic Rotation signal of linearly polarized light coherent layout imprison.
5. the difference detecting method of coherent layout imprison magneto-optic effect according to claim 4, is characterized in that, the buffer gas arranging in described alkali metal atom steam bubble is inert gas, and pressure is 3-5Torr, and temperature is controlled at 40-60 ° of C.
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| CN104868913A (en) * | 2015-04-30 | 2015-08-26 | 江汉大学 | Coherent population trapping atomic frequency standard |
| CN105242521A (en) * | 2015-11-13 | 2016-01-13 | 中国科学院武汉物理与数学研究所 | Device and method for achieving minitype CPT atomic clock physical system |
| CN105699919A (en) * | 2016-03-01 | 2016-06-22 | 中国科学院武汉物理与数学研究所 | Implementation method for difference detection of coherent population trapping magnetometer |
| CN109245764A (en) * | 2018-11-09 | 2019-01-18 | 成都天奥电子股份有限公司 | A kind of rubidium atomic clock device based on difference optical detection |
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Application publication date: 20140730 |