JPS6334638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas cell type atomic oscillator using a coaxial cavity resonator.

4 and 5 are schematic diagrams showing a conventional gas cell type atomic oscillator.

Conventionally, a gas cell type atomic oscillator 1 includes an optical microwave section 2, a voltage-controlled crystal oscillator 3, a frequency synthesizer 5, etc., as shown in FIG. Lamp cell 6 encapsulating the isotope Rb ⁸⁷ , lamp excitation coil 7, reflector 9, lamp exciter 10, Rb ⁸⁵
It has a filter cell 11 in which Rb 87 is enclosed, a cylindrical cavity resonator 12, a resonance cell 13 in which Rb ⁸⁷ is enclosed, a photodetector 15, an amplifier 16, a frequency multiplier 17, and the like. Heaters 19, 20, 21 connected to temperature control devices 22, 23, 25 are wound around each cell 6, 11, 13. 21, the temperature is controlled to the optimum temperature.

During operation, the lamp cell 6 emits high-frequency discharge light by the lamp exciter 10, and among the generated light, unnecessary wavelength light is absorbed by the filter cell 11, and only the desired wavelength light enters the resonance cell 13. do. Furthermore, the output of the crystal oscillator 3 is sent to a frequency synthesizer 5.
The frequency multiplier 17 raises the resonance frequency of Rb ⁸⁷ to around f _Rb =6834.68...[MHz], and adds it to the cavity resonator 12 as a microwave MW. Microwave applied to cavity resonator 12
When MW matches the resonant frequency f _Rb of Rb ⁸⁷ in the resonant cell 13, the light passing through the resonant cell 13 is absorbed due to optical microwave double resonance, thereby reducing the detection output S1 of the photodetector 15. . This detection output S1 is sent to the crystal oscillator 3 via the servo amplifier 16.
In addition, the oscillation frequency f _QZ of the oscillator 3 is stabilized and controlled based on the resonance frequency f _Rb . Normally, the resonance frequency f _Rb is extremely stable, so the oscillation frequency f _QZ is highly stable.

By the way, although the atomic oscillator 1 ^is highly stable, it has the disadvantage of increasing the size of the entire device, so as shown in ^FIG . Rb ⁸⁵ out of 13
A method has also been adopted in which unnecessary wavelength components of the light from the lamp cell 6 are absorbed, and the filter cell 11 is omitted to reduce the size of the optical microwave section 2.
However, the cylindrical cavity resonator 12, which occupies a large proportion of the oscillator 1, remains as it is. The cylindrical cavity resonator 12 is the most common excitation mode of TE ₀₁₁ , and the inner diameter of the cylinder is approximately 70 [mm], which has been the biggest obstacle in reducing the size of the optical microwave section 2. .

Therefore, a proposal has been made to use a coaxial cavity resonator with a large degree of freedom instead of the cylindrical cavity resonator 12 in an attempt to downsize the cavity, but in this case, the excitation mode of the cavity becomes the TEM mode. , the magnetic field is distributed in the circumferential direction of the cavity resonator. For that purpose, C-
A magnetic field (static magnetic field) is generated by energizing a central conductor placed near the central axis of the cavity resonator so as to be parallel to this, but in this case, the C-magnetic field inside the resonator The intensity becomes non-uniform as it decreases as it moves away from the central conductor, and the half-width of the atomic resonance line expands, resulting in the disadvantage that the stability of the atomic oscillator 1 deteriorates.

Therefore, the present invention provides a coaxial cavity resonator provided with a center conductor as a cavity resonator, and
One or more auxiliary conductors are installed outside the resonator in parallel with the center conductor, and the center conductor and the auxiliary conductors are configured to homogenize the C-magnetic field in the resonator, thereby achieving the above-mentioned It is an object of the present invention to provide a gas cell type atomic oscillator that eliminates the drawbacks.

The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the gas cell type atomic oscillator according to the present invention, FIG. 2 is a diagram showing the state of magnetic field formation in the coaxial cavity resonator of the oscillator in FIG. 1, and FIG. It is a graph showing the relationship between the distance from the center conductor of a coaxial cavity resonator and the magnetic field strength.

As shown in FIG. 1, the gas cell type atomic oscillator 1 includes an optical microwave section 2 and a voltage-controlled crystal oscillator 3.
However, the same parts as those already explained in FIGS. 4 and 5 are given the same reference numerals, and the explanation of those parts will be omitted. The optical microwave section 2 is provided with a coaxial cavity resonator 26, and a center conductor 26a is provided in the central portion of the resonator 26 along the axial direction of the resonator 26. 2
Two auxiliary conductors 27 and 27' are provided around the central conductor 26a in parallel to the central conductor 26a.

Since the present invention has the above-described configuration, when the gas cell type atomic oscillator 1 is operated, the excitation mode of the coaxial cavity resonator 26 by the microwave MW becomes the TEM mode, and the magnetic field is generated in the circular direction of the resonator 26. Distributed circumferentially. Therefore, by flowing the current I _C through the center conductor 26a in the direction of the arrow in the figure, the resonator 2
6, as shown in FIG.
A centered concentric magnetic field 29 is formed parallel to the magnetic field generated by the microwave MW from the frequency multiplier 17. The strength H _C of this magnetic field 29 is
As shown in FIG. 3, it is inversely proportional to the distance r from the center conductor 26a, and becomes smaller as the distance from the conductor 26a increases. Therefore, a current I _S is passed through the auxiliary conductors 27, 27', and auxiliary magnetic fields 30, 30' are generated concentrically around the auxiliary conductors 27, 27', but the strength of the auxiliary magnetic fields 30, 30' is H _S As shown in FIG. 3, increases with the distance r from the center conductor 26a. Therefore, the composite magnetic field obtained by combining them, that is,
The strength of the C-magnetic field H _T in the resonator 26 is equal to the magnetic field 29,
30, 30', and near the uniform magnetic field zone 31, which has the highest degree of uniformity.
By installing a resonance cell in which both Rb ⁸⁷ and Rb ⁸⁵ are sealed, an atomic resonance line having a small half-width and a high Q can be obtained.

Note that in the above embodiment, the auxiliary conductors 27, 27'
We have described the case where two auxiliary conductors are provided, but the auxiliary conductor 2
Of course, one or more 7, 27' may be provided depending on the installation location of the resonance cell. Further, in the above embodiment, the direction of the auxiliary magnetic fields 30, 30' is
Although the magnetic field 29 is made to act in the direction of strengthening the magnetic field 29 within the resonator 26, it is also possible to make the direction of the auxiliary magnetic fields 30 and 30' act in the direction of weakening the magnetic field 29 to synthesize a C-magnetic field of a special strength. It is possible.

As explained above, according to the present invention, one or more auxiliary conductors 27, 27' are provided outside the coaxial cavity resonator 26 in parallel with the center conductor 26a, and the auxiliary magnetic field by the auxiliary conductors 27, 27' is Since the magnetic field 29 caused by the center conductor 26a can be made uniform by the 30 and 30', the atomic resonance line in the resonator 26 can have a small half-width, and the stability of the atomic oscillator 1 can be further improved. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the gas cell type atomic oscillator according to the present invention, FIG. 2 is a diagram showing the state of magnetic field formation in the coaxial cavity resonator of the oscillator in FIG. 1, and FIG. is a graph showing the relationship between the distance from the center conductor of a coaxial cavity resonator and the magnetic field strength, the fourth
1 and 5 are schematic diagrams showing a conventional gas cell type atomic oscillator. 1... Gas cell type atomic oscillator, 2... Optical microwave section, 26... Coaxial cavity resonator, 26a...
Center conductor, 27, 27'...Auxiliary conductor, H _T ...C
- Magnetic field strength.

Claims (1)

[Claims] 1. In a gas cell type atomic oscillator having an optical microwave section provided with a cavity resonator, a coaxial cavity resonator provided with a center conductor is provided as the cavity resonator, and outside the resonator, 1 A gas cell type atomic oscillator constructed in such a manner that more than one auxiliary conductor is installed in parallel to a center conductor, and the C-magnetic field in the resonator can be made uniform by the center conductor and the auxiliary conductors.