WO2001026231A1 - Apparatus for the generation of a reference frequency - Google Patents
Apparatus for the generation of a reference frequency Download PDFInfo
- Publication number
- WO2001026231A1 WO2001026231A1 PCT/IB2000/001411 IB0001411W WO0126231A1 WO 2001026231 A1 WO2001026231 A1 WO 2001026231A1 IB 0001411 W IB0001411 W IB 0001411W WO 0126231 A1 WO0126231 A1 WO 0126231A1
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- WIPO (PCT)
- Prior art keywords
- generating
- reference frequency
- frequency
- radiation
- transition
- Prior art date
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Classifications
-
- G—PHYSICS
- G04—HOROLOGY
- G04F—TIME-INTERVAL MEASURING
- G04F5/00—Apparatus for producing preselected time intervals for use as timing standards
- G04F5/14—Apparatus for producing preselected time intervals for use as timing standards using atomic clocks
-
- G—PHYSICS
- G04—HOROLOGY
- G04F—TIME-INTERVAL MEASURING
- G04F5/00—Apparatus for producing preselected time intervals for use as timing standards
- G04F5/14—Apparatus for producing preselected time intervals for use as timing standards using atomic clocks
- G04F5/145—Apparatus for producing preselected time intervals for use as timing standards using atomic clocks using Coherent Population Trapping
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/26—Automatic control of frequency or phase; Synchronisation using energy levels of molecules, atoms, or subatomic particles as a frequency reference
Definitions
- CPT Coherent Population Trapping
- Said coupling is produced, for instance, by coupling two hyperfine levels of the S state of the atom with an excited P levels, by means of two laser radiations with a corresponding frequency.
- a coherence phenomenon occurs, so that the atoms are no longer able to absorb energy from the laser radiations.
- coherence causes a dark line to appear in the atom fluorescence spectrum.
- CP T phenomenon produces the coupling of the two hyperfine levels without influencing their population, that remains in thermal equilibrium.
- Said coherence originates further an oscillating magnetization that, if the atomic system is placed inside a suitable microwave cavity, , leads to the emission of a coherent microwave radiation, i.e. a maser emission.
- FIG. 1 is shown a basic diagram of an apparatus for generating a reference frequency, making use of the CPT phenomenon, according to the prior art. Further details regarding such an apparatus for generating a reference frequency can be found in the publication Coherent population trapping in cesium: dark lines and coherent microwave emission " di JNanier, A. Godone, F. Levi. Physical Review A, vol. 58, n. 3. September 1998, p. 2345-2358, whose contents are here embodied for reference.
- Said apparatus comprises a laser 10, emitting a radiation L of wavelenght WL.
- ground state 6S ⁇ /2 and excited state 6P 3 / 2 are shown, that are divided by a transition called D 2 transition and corresponding to a 852 n wavelenght.
- Modulated radiation LP is send, through an attenuator 13. a polarizer 14 and a quarte-wave plate 15. used for obtaining circularly polarized light, to a microwave cavity 16 continining a cesium cell 17.
- Said cesium cell 17 is a quartz cell containing cesium and a buffer gas. nitrogen for instance, that, as it is known, it is used for decreasing the width of the dark line produced by the CPT phenomenon, due to the Dicke effect.
- the synthesis block 12 that substantially corresponds to a microwave frequency generator, adnt that in other types of embodiment, can directly drive the injection current of the laser, is locked through phase or frequency modulation techniques to the frequency of the dark line or of the microwave emission.
- FIG. 1 shows a basic diagram of an apparatus for generating a reference frequency according the prior art
- - figure 2 shows a diagram of atomic levels used by the apparatus for generating a reference frequency of figure 1 :
- - figure 2a shows a basic spectral diagram of a quantity used by the apparatus for generating a reference frequency of figure 1 ;
- a transition in order to produce the CPT phenomenon in the alkali-metal atom, a transition is used that is associated to symmetrical dipole matrix elements, i.e. the transition from line transition Di, in substitution of a transition associated to asymmetrical dipole matrix elements, transition Di. for obtaining to use for the stimulation two laser radiations that are symmetrical with respect to power distribution.
- this allows for using two sidebands that are symmetrical with respect to power distribution.
- e D ⁇ of the cesium 133 and rubidium 87 are shown.
- Dipole matrix elements DM are indicated on the side of the lines representing the transitions.. In rubidium 87 case . the line D 2 .
- corresponds to a frequency gap of 6.8 GFIz. while 9.2 GHz is the gap for cesium 133.
- figure 4 an apparatus for generating a reference frequency according to the invention is shown.
- An electro-optical modulator 1 1 1 generates a modulated radiation LPR, i.e. generates the sidebands, as the modulator 1 1 shown in figure 1.
- the electro-optical modulator 1 1 1 sends said modulated radiation LPR to a beam splitterl29, that, besides transmitting the modulated radiation LPR to a cell 1 17 placed inside a microwave cavity 1 16, transmits said radiation LPR to frequency lock block 128. that produces a frequency reference to stabilize the laser 1 10.
- the modulated radiation LPR is transmitted, as before said, to the microwave cavity 1 16. equipped with a magnetic shield 121. that contains a rubidium cell 1 17. i.e. a quartz cell containing rubidium 87 and a buffer gas mixture.
- Microwave output power Pout is taken a transmitted to superheterodyne synthesis block 130. comprising a microwave amplifier 131 , receiving power Pout, amplifying it in suitable manner, and transmitting said power Pout then to a mixing block 132 and, from there, to a synchronous detector 135. that detects the frequency corresponding to the peak of the output power Pout and drives, through a servo block 136 a controlled oscillator 137, that operates at a natural frequenc) of 10 MHz.
- the output frequency FO of the controlled oscillator 137 is sent to a multiplier 133. that multiplies it by a factor m and sends to the mixing block 132. according the well-known superheterodyne technique.
- the output frequency FO of the controlled oscillator 137 is sent, multiplied by a factor n through a multiplier 134. to drive the electro-optical modulator 1 1 1 .
- a clock signal CK is taken from the output of the controlled oscillator 137, that is consequently locked to the atomic transition active in the cell 1 17: said clock signal C.I is the reference frequenc) supplied by the atomic clock.
- the superheterodyne synthesis block 130 is generated the driving frequency of the electro-optical modulator 1 1 1 , so that the modulated radiation is locked to the frequency of the peak of the output power Pout, originated by the maser emission in the cavity 1 16.
- the servo circuit for obtaining a clock signal from the fluorescence power Pfl will be analogous to the superheterodyne synthesis block 130, that operates with the microwave power Pout.
- an amplitude servo circuit 140 substantially analogous in operation to the superheterodyne synthesis block 130. that controls an amplitude modulator 141. interposed on the path of the modulated radiation LPR.
- the amplitude servo circuit 140 takes the microwave power Pout and derives an amplitude correction signal EA. used for controlling the amplitude modulator 141.
- the apparatus for generating a reference frequency advantageously solves the problem of the frequenc) shift of the maser emission and/or dark line, by using a transition endowed with dipole matrix elements symmetrical.
- th e power distribution in the harmonics of the spectrum of the modulated radiation used for the simulation can be equal, minimizing the effect of frequency shift due to the amplitude of the modulation used for frequenc) locking the local oscillator.
- transitions marked by symmetrical dipole matrix elements can be used, as transition Di in cesium 133 or rubidium 85.
Abstract
Apparatus for generating a reference frequency, comprising means for generating electromagnetic coherent radiation used for exciting two hyperfine atomic levels of a material in order to cause a Coherent Population Trapping phenomenon to occur and to measure the frequency of a radiation emitted by said material in consequence of the excitation, in order to use such frequency as reference frequency. According to the invention, the two hyperfine levels are chosen apt to originate a transition (D1) in said material, to which transition a symmetrical dipole matrix (DM) is associated, in order to reduce the frequency shift and asymmetries in reference frequency (CK).
Description
APPARATUS FOR THE GENERATION OF A REFERENCE FREQUENCY
DESCRIPTION
The present invention relates to an apparatus for generating a reference frequency , comprising means for generating electromagnetic coherent radiation used for exciting two hyperfine atomic levels of a material in order to cause a Coherent Population Trapping phenomenon to occur and to measure the frequency of a radiation emitted by said material in consequence of the excitation, in order to use such frequency as reference frequency.
In application in fields like, for instance, laser cooling, magnetometry. laser emissions and, in particular, atomic frequency standards, it is known, in order to obtain a microwave coherent radiation emission, to make use of the phenomenon called Coherent Population Trapping (CPT), that requires, in alkali-metal atoms like cesium or rubidium for instance, to couple two ground states to an excited state, by means of two resonant and mutually coherent radiations. Said coupling determines coherence effects in the excitation process.
Said coupling is produced, for instance, by coupling two hyperfine levels of the S state of the atom with an excited P levels, by means of two laser radiations with a corresponding frequency. When the frequency of said radiation resonates with the transitions, a coherence phenomenon occurs, so that the atoms are no longer able to absorb energy from the laser radiations. Thus, coherence causes a dark line to appear in the atom fluorescence spectrum. So, CP T phenomenon produces the coupling of the two hyperfine levels without influencing their population, that remains in thermal equilibrium. Said coherence originates further an oscillating magnetization that, if the atomic system is placed inside a suitable microwave cavity, , leads to the emission of a coherent microwave radiation, i.e. a maser emission. The output power is function of the frequency difference between the two CPT stimulating radiations and the maximum power is obtained at the value of the hyperfine frequency. In figure 1 is shown a basic diagram of an apparatus for generating a reference frequency, making use of the CPT phenomenon, according to the prior art. Further details regarding such an apparatus for generating a reference frequency can be found in the publication Coherent population trapping in cesium: dark lines and coherent microwave emission " di JNanier, A. Godone, F. Levi. Physical Review A, vol. 58, n. 3. September 1998, p. 2345-2358, whose contents are here embodied for reference.
Said apparatus comprises a laser 10, emitting a radiation L of wavelenght WL. In figure 2 are shown schematically the energy levels of cesium 133 that are employed. Ground state 6Sι/2 and excited state 6P3/2 are shown, that are divided by a transition called D2 transition and corresponding to a 852 n wavelenght. Ground state Sι/2 comprises two hyperfine levels corresponding to F=3, and F=4, divide by 9,2 GHz.
The wavelenght WL of radiation L emitted by laser 10 corresponds to the transition from the hyperfine level 6S1/2 F=3, F=4 to excited state P3/2. An electro-optical modulator 1 1. driven by a synthesis block 12 to a frequency of 4.6 GHz, produces a modulated radiation, that comprises in its spectrum lateral band, spaced in frequency by 9.2 GHz. and necessary for the stimulation, i.e. corresponding to the transition between hyperfine levels 6S1/2 F=3. 6Sι/2 F=4 shown in figure 2.
In figure 2a the spectrum of the modulated radiation LP is illustated. that shows a carrier JO at the frequency corresponding to wavelenght WL, and two sidebands .11 , i.e. the first harmonics of radiation L. Higher order harmonics J2 are further shown. Sidebands J 1 , whose amplitude. as it can be observed, is enhanced by the modulation, are at wavelenghts at to stimulate the levels 6S1/2 F=3. F=4, and originate the CPT phenomenon.
Modulated radiation LP is send, through an attenuator 13. a polarizer 14 and a quarte-wave plate 15. used for obtaining circularly polarized light, to a microwave cavity 16 continining a cesium cell 17. Said cesium cell 17 is a quartz cell containing cesium and a buffer gas. nitrogen for instance, that, as it is known, it is used for decreasing the width of the dark line produced by the CPT phenomenon, due to the Dicke effect.
The atomic system in the cesium cell 17, excited by the modulated radiation LP, generates a microwave field, the detection of which allows for obtaining a clock signal. The microwa\ e cavity 16, that operates in TE01 1 mode, is placed in a magnetic field BO. created by a solenoid 25 in order to produce, by Zeeman effect, the separation of the Zeeman sublevels with different quantic number.
Outside the microwave cavity 16 a magnetic shield 21 is provided, in order to have a good uniformity and stability of the magnetic field. A fluorescence detector 18. placed in a suitable hole 19 of the cavity 16, measures a fluorescence power Pfl, while the output laser radiation LU. to which a transmitted power Ptr is associated, exits from a hole 20.
From the microwave cavity 16 is further taken, through a coupling loop 23, the microwave
output power Pout, that is delivered to an heterodyne receiver 22.
It is possible to use either the coherent microwave emission or the dark line for building an atomic frequency standard.
It is possible, in fact, o obtain that the synthesis block 12, that substantially corresponds to a microwave frequency generator, adnt that in other types of embodiment, can directly drive the injection current of the laser, is locked through phase or frequency modulation techniques to the frequency of the dark line or of the microwave emission.
Since, for instance, the microwave emission frequency, to which the laser driving generator is locked, is taken in correspondence of the maximum of the power, there are some drawbacks regarding applications like atomic frequency standards, because of shifts and asymmetries of the spectrum from which the microwave emission frequency is obtained, and of the dark line in the fluorescence spectrum that is used as a reference.
Such shifts arise because of different factors, depending from magnetic field, from collisions in the buffer gas and, in particular, depending from the laser radiations used to excite the atoms.
It is the object of the present invention to solve the above drawbacks and provide an apparatus for generating a reference frequency, having a more efficient and improved performance with respect to existing solutions.
In this frame, it is the main object of the present invention to provide an apparatus for generating a reference frequency that allows for obtaining a frequency stabilized maser emission and in which the frequency shift and asymmetries due to excitation laser radiation are strongly reduced.
In order to achieve such aims, it is the object of the present invention to provide an apparatus for generating a reference frequency and/or a method for stimulating an apparatus for generating a reference frequency and/or an atomic clock incorporating the features of the annexed claims, which form an integral part of the description herein.
Further objects, features and advantages of the present invention will become apparent from the following detailed description and annexed drawings, which are supplied by way of non limiting example, wherein: - figure 1 shows a basic diagram of an apparatus for generating a reference frequency according the prior art;
- figure 2 shows a diagram of atomic levels used by the apparatus for generating a reference frequency of figure 1 :
- figure 2a shows a basic spectral diagram of a quantity used by the apparatus for generating a reference frequency of figure 1 ;
- figure 3 shows a diagram of atomic levels used by the apparatus for generating a reference frequency of figure 4; - figure 4 shows a basic diagram of an apparatus for generating a reference frequency according to the invention.
The invention is based on the observation that frequency shift of the microwave emission and of the dark line, produce by the radiation incident on the cell, are due to power distribution of the laser harmonics, also called sidebands, through two contributions: a first contribution from the frequency shift originated by the power of the laser radiation incident on the cell, independent from the frequency behavior of the laser, and a second frequency shift depending in a quadratic manner from the frequency behavior of the laser.
In rubidium and cesium the line D2, is part of a spectral lines doublet, that is produced because of the coupling between angular orbital momentum and outer electron spin momentum. The energetic levels doublet is completed by the line Di .
The interaction between the incident optical radiation and the atom, a cesium atom for instance, is identified by the dipole matrix elements.
According to the invention, in order to produce the CPT phenomenon in the alkali-metal atom, a transition is used that is associated to symmetrical dipole matrix elements, i.e. the transition from line
transition Di, in substitution of a transition associated to asymmetrical dipole matrix elements, transition Di. for obtaining to use for the stimulation two laser radiations that are symmetrical with respect to power distribution. In particular this allows for using two sidebands that are symmetrical with respect to power distribution. In figure 3 transition D| e D^ of the cesium 133 and rubidium 87 are shown. Dipole matrix elements DM are indicated on the side of the lines representing the transitions.. In rubidium 87 case . the line D2. for instance, that is the transition from ground level F=l and F=2 to excited level F'=2. bears the value 1/2 and is a symmetrical transition, while transition from level F=l . F=2 to excited level F'=l is asymmetrical. Because of the small separation in frequency the two lines are separately excitable. For the transition Di . on the other hand, the value of dipole matrix elements DM is respectively - 1 /3Λ/2 and + 1/3V2. and -1/2, +1/2, i.e. dipole matrix elements DM are fully symmetrical.
It is observed, further, that for rubidium 87. transition D| corresponds to a frequency gap of 6.8 GFIz. while 9.2 GHz is the gap for cesium 133.
In figure 4 an apparatus for generating a reference frequency according to the invention is shown.
Said apparatus for generating a reference frequency according to the invention comprises a laser 1 10, emitting a radiation LR at a wavelenght WLR of 794,98 nm, modulated at a frequency of 6,8/2n GHz. where n=l ,2,3, that couples the rubidium 87 levels for the line D) .
An electro-optical modulator 1 1 1 generates a modulated radiation LPR, i.e. generates the sidebands, as the modulator 1 1 shown in figure 1.
The electro-optical modulator 1 1 1 sends said modulated radiation LPR to a beam splitterl29, that, besides transmitting the modulated radiation LPR to a cell 1 17 placed inside a microwave cavity 1 16, transmits said radiation LPR to frequency lock block 128. that produces a frequency reference to stabilize the laser 1 10.
The modulated radiation LPR is transmitted, as before said, to the microwave cavity 1 16. equipped with a magnetic shield 121. that contains a rubidium cell 1 17. i.e. a quartz cell containing rubidium 87 and a buffer gas mixture. Microwave output power Pout is taken a transmitted to superheterodyne synthesis block 130. comprising a microwave amplifier 131 , receiving power Pout, amplifying it in suitable manner, and transmitting said power Pout then to a mixing block 132 and, from there, to a synchronous detector 135. that detects the frequency corresponding to the peak of the output power Pout and drives, through a servo block 136 a controlled oscillator 137, that operates at a natural frequenc) of 10 MHz. The output frequency FO of the controlled oscillator 137 is sent to a multiplier 133. that multiplies it by a factor m and sends to the mixing block 132. according the well-known superheterodyne technique.
Further, the output frequency FO of the controlled oscillator 137 is sent, multiplied by a factor n through a multiplier 134. to drive the electro-optical modulator 1 1 1 . A clock signal CK is taken from the output of the controlled oscillator 137, that is consequently locked to the atomic transition active in the cell 1 17: said clock signal C.I is the reference frequenc) supplied by the atomic clock.
Thus, through the superheterodyne synthesis block 130 is generated the driving frequency of the electro-optical modulator 1 1 1 , so that the modulated radiation is locked to the frequency of the peak of the output power Pout, originated by the maser emission in the cavity 1 16.
It is possible, of course, to lock to dark line frequency, derived by the fluorescence spectrum, obtained as shown in figure 1 , i.e. directly by the spectrum of a sensor analogous to the fluorescence detector 18, that measures a fluorescence power Pfl spectrum. The servo circuit
for obtaining a clock signal from the fluorescence power Pfl will be analogous to the superheterodyne synthesis block 130, that operates with the microwave power Pout. In figure 4 is further shown an amplitude servo circuit 140, substantially analogous in operation to the superheterodyne synthesis block 130. that controls an amplitude modulator 141. interposed on the path of the modulated radiation LPR. The amplitude servo circuit 140 takes the microwave power Pout and derives an amplitude correction signal EA. used for controlling the amplitude modulator 141.
The control is performed in a similar way as to what proposed for the optical pumping standards, i.e. in J. Camparo. Phys. Rev. Lett. Vol. 80, p. 222, Jan 1998. In other words, the Rabi resonances technique is used. To control the CPT phenomenon that forms the basis of the present invention. It can be demonstrated, indeed, that, in presence of the CPT phenomenon, stimulated in the cell 1 17, an amplitude modulation of the powr of the laser 1 10, that is used to excite the transition, generates a resonance at a frequency equal to Rabi frequency in output signal spectrum, i.e. the microwave power Pout. Through the servo circuit 140 a locking to this resonance frequency is performed, in order to stabilize the power of the modulated radiation LPR incident on the cell 1 17.
From the above description the features of the present invention as well as the relevant advantages thereof are clear. The apparatus for generating a reference frequency according to the invention advantageously solves the problem of the frequenc) shift of the maser emission and/or dark line, by using a transition endowed with dipole matrix elements symmetrical. In this wa>. advantageously, th e power distribution in the harmonics of the spectrum of the modulated radiation used for the simulation can be equal, minimizing the effect of frequency shift due to the amplitude of the modulation used for frequenc) locking the local oscillator. Further, being now possible to use excitation radiations with a symmetrical power, a greater compensation of the residual light shift, both for amplitude and power, is also obtained b) suitably varying the modulation index, i.e. using a modulation depth such as to eliminate the residual light shift due to all the harmonics, since the principal light shift effect has been eliminated by symmetrizing the sidebands. The use of rubidium 87 is particularly advantageous since it presents a lower number of
Zeeman levels in state associate to D| transition, with respect to cesium 133, for istancc, so that the levels have a larger population available for the clock transition. Further, advantageousl) . being the frequency asssociated to Di transition of rubidium 87 only 6.8
GHz, this allows for using a larger microwave cavity and obtaining a larger atomic volume in the cell, producing in this way a higher output power and a better signal to noise ratio, that determine a better stability of the frequency reference.
It is obvious that many changes are possible for the man skilled in the art to the apparatus for generating a reference frequency described above by way of example, without departing from the novelty spirit of the innovative idea, and it is also clear that in practical actuation of the invention the components may often differ in form and size from the ones described and be replaced with technical equivalent elements.
By way of example, transitions marked by symmetrical dipole matrix elements can be used, as transition Di in cesium 133 or rubidium 85.
Claims
1. Apparatus for generating a reference frequency , comprising means for generating electromagnetic coherent radiation used for exciting two hyperfine atomic levels of a material in order to cause a Coherent Population Trapping phenomenon to occur and to measure the frequency of a radiation emitted by said material in consequence of the excitation, in order to use such frequency as reference frequency, characterized in that the two hyperfine levels are chosen apt to originate a transition (Di) in said material, to which transition a symmetrical dipole matrix (DM) is associated, in order to reduce the frequency shift and asymmetries in reference frequency (CK).
2. Apparatus for generating a reference frequency according to claim 1 , characterized in that said transition is stimulated through the transizione D| in alkali-metals..
3. Apparatus for generating a reference frequency according to claim 2, characterized in that means for generating electromagnetic radiation (1 10. I l l ) generates excitation modulated laser radiations (LPR), whose sidebands have substantially the same power density.
4. Apparatus for generating a reference frequency according to claim 3, characterized in that the alkali-metal is rubidium 87.
5. Apparatus for generating a reference frequency according to claim 3, characterized characterized in that the alkali-metal is cesium 133.
6. Apparatus for generating a reference frequency according to claim 3, characterized characterized in that the alkali-metal is rubidium 85.
7. Apparatus for generating a reference frequency according to one or more of the preceding claims, characterized in that the cell (1 1 7) is contained in a microwave cavity ( 1 16) and the mesured frequency of the radiation emitted by the material because of the excitation in order to obtain the reference frequency (CK) is the peak frequency of a microwave coherent radiation (Pout).
8. Apparatus for generating a reference according to one or more of the preceding claims. characterized in that the measured frequency of the radiation emitted by the material following the excitation for obtaining the reference frequency (CK) is obtained by lines of the fluorescence spectrum (Pfl) of the material, in particular of the so-called dark line.
9. Method for stimulating an apparatus for generating a reference frequency, that provides for exciting two hyperfine atomic levels of a material contained in a microwave cavity through laser radiations in order to produce a Coherent Population Trapping type phenomenon and for measuring the frequency of the resulting fluorescence spectrum and/or the frequency of coherent microwave radiation generated in a microwave cavity characterized by the choosing the two hyperfine levels so that they originate a transition to which a symmetrical dipole matrix is associated in order to reduce the frequency shifts.
10. . Method for stimulating an apparatus for generating a reference frequency , according to the preceding claim, characterized by using the lateral band or harmonics of the laser radiation employed to excite the hyperfine levels that produce a transition to which a symmetrical dipole matrix is associated, and in that said sidebands also have a symmetrical power distribution.
1 1. Method for stimulating an apparatus for generating a reference frequency , according to the preceding claim, characterized by modulating the laser radiation (LPR) incident on the cell
( 1 16) with a modulation depth that eliminates the residual light shift due to the harmonics (JO, .11. J2). after eliminating the main contribution to the light shift by symmetrizing the sidebands (J l ).
12. Method for stimulating an apparatus for generating a reference frequency , according to one or more of the preceding claim characterized by using a servo circuit ( 140) and amplitude modulating means ( 141 ) for stabilizing the amplitude of the laser radiation (LPR) incident on the cell ( 1 16), said servo circuit (140) operating through the Rabi resonances technique on the output signal spectrum (Pout).
13. Atomic clock characterized by using the apparatus for generating a reference frequency according to claim 1 and/or the method for stimulating an apparatus for generating a reference frequency according to claim 10 to the present description and enclosed drawings.
14. Apparatus for generating a reference frequency and/or method for stimulating an apparatus for generating a reference frequency according to the teachings of the present description and enclosed drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU79372/00A AU7937200A (en) | 1999-10-05 | 2000-10-04 | Apparatus for the generation of a reference frequency |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ITTO99A000853 | 1999-10-05 | ||
| ITTO990853 IT1307355B1 (en) | 1999-10-05 | 1999-10-05 | APPARATUS FOR GENERATING A REFERENCE FREQUENCY. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2001026231A1 true WO2001026231A1 (en) | 2001-04-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2000/001411 WO2001026231A1 (en) | 1999-10-05 | 2000-10-04 | Apparatus for the generation of a reference frequency |
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|---|---|
| AU (1) | AU7937200A (en) |
| IT (1) | IT1307355B1 (en) |
| WO (1) | WO2001026231A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1577720A2 (en) * | 2004-03-18 | 2005-09-21 | Agilent Technologies, Inc.(a Delaware Corporation) | Method and apparatus for reducing errors due to line asymmetry in devices utilizing coherent population trapping |
| CN100589049C (en) * | 2007-09-13 | 2010-02-10 | 中国科学院武汉物理与数学研究所 | Coherent maser radiation cold atomic clock |
| CN102063054A (en) * | 2011-02-22 | 2011-05-18 | 合肥威师智能电子电器厂 | CPT (Coherent Population Trapping) atomic clock |
| WO2014034955A1 (en) * | 2012-08-30 | 2014-03-06 | Ricoh Company, Ltd. | Atomic oscillator and interrogation method of coherent population trapping resonance |
| CN103823356A (en) * | 2014-03-07 | 2014-05-28 | 中国科学院武汉物理与数学研究所 | PXI (PCI eXtensions for Instrumentation) system-based passive CPT (Coherent Population Trapping) atomic clock experimental facility and method |
| CN113206435A (en) * | 2021-04-14 | 2021-08-03 | 温州激光与光电子协同创新中心 | Multi-wavelength laser generating device based on mixed atom air chamber |
-
1999
- 1999-10-05 IT ITTO990853 patent/IT1307355B1/en active
-
2000
- 2000-10-04 AU AU79372/00A patent/AU7937200A/en not_active Abandoned
- 2000-10-04 WO PCT/IB2000/001411 patent/WO2001026231A1/en active Search and Examination
Non-Patent Citations (4)
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| GODONE ET AL.: "A New Atomic Frequency Standard: The coherent Population Trapping Cs Maser", 1998 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS DIGEST, 1998, pages 175 - 176, XP002159308, ISBN: 0-7803-5018-9, Retrieved from the Internet <URL:http://iel.ihs.com:80/cgi-bin/iel_cgi?sess=349284831&prod=IEL&page=%2fiel4%2f5667%2f15175%2f00699845%2epdf> [retrieved on 20010202] * |
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| VANIER J ET AL: "COHERENT POPULATION TRAPPING IN CESIUM: DARK LINES AND COHERENT MICROWAVE EMISSION", PHYSICAL REVIEW, A. GENERAL PHYSICS,AMERICAN INSTITUTE OF PHYSICS. NEW YORK,US, vol. 58, no. 3, September 1998 (1998-09-01), pages 2345 - 2358, XP000978042, ISSN: 1050-2947 * |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1577720A2 (en) * | 2004-03-18 | 2005-09-21 | Agilent Technologies, Inc.(a Delaware Corporation) | Method and apparatus for reducing errors due to line asymmetry in devices utilizing coherent population trapping |
| EP1577720A3 (en) * | 2004-03-18 | 2005-11-30 | Agilent Technologies, Inc.(a Delaware Corporation) | Method and apparatus for reducing errors due to line asymmetry in devices utilizing coherent population trapping |
| US7345553B2 (en) | 2004-03-18 | 2008-03-18 | Agilent Technologies, Inc. | Method and apparatus for reducing errors due to line asymmetry in devices utilizing coherent population trapping |
| CN100589049C (en) * | 2007-09-13 | 2010-02-10 | 中国科学院武汉物理与数学研究所 | Coherent maser radiation cold atomic clock |
| CN102063054A (en) * | 2011-02-22 | 2011-05-18 | 合肥威师智能电子电器厂 | CPT (Coherent Population Trapping) atomic clock |
| CN102063054B (en) * | 2011-02-22 | 2012-09-05 | 合肥威师智能电子电器厂 | CPT (Coherent Population Trapping) atomic clock |
| WO2014034955A1 (en) * | 2012-08-30 | 2014-03-06 | Ricoh Company, Ltd. | Atomic oscillator and interrogation method of coherent population trapping resonance |
| JP2014049886A (en) * | 2012-08-30 | 2014-03-17 | Ricoh Co Ltd | Atomic oscillator and method for exciting cpt resonance |
| CN104685788A (en) * | 2012-08-30 | 2015-06-03 | 株式会社理光 | Atomic oscillator and interrogation method of coherent population trapping resonance |
| EP2891247A4 (en) * | 2012-08-30 | 2015-10-28 | Ricoh Co Ltd | Atomic oscillator and interrogation method of coherent population trapping resonance |
| US9444476B2 (en) | 2012-08-30 | 2016-09-13 | Ricoh Company, Ltd. | Atomic oscillator and interrogation method of coherent population trapping resonance |
| CN104685788B (en) * | 2012-08-30 | 2017-11-03 | 株式会社理光 | The atomic oscillator and method for inquiring of coherent population trapping resonance |
| CN103823356A (en) * | 2014-03-07 | 2014-05-28 | 中国科学院武汉物理与数学研究所 | PXI (PCI eXtensions for Instrumentation) system-based passive CPT (Coherent Population Trapping) atomic clock experimental facility and method |
| CN113206435A (en) * | 2021-04-14 | 2021-08-03 | 温州激光与光电子协同创新中心 | Multi-wavelength laser generating device based on mixed atom air chamber |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1307355B1 (en) | 2001-11-06 |
| AU7937200A (en) | 2001-05-10 |
| ITTO990853A1 (en) | 2001-04-05 |
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