JPH0220926A - Atomic beam resonance device - Google Patents

Abstract

PURPOSE:To improve frequency accuracy of an atomic beam oscillator by providing an optical switch for turning ON/OFF repeatedly a stimulating light by the time required for allowing an atom in an atomic beam to pass through a stimulating light part and the time required for allowing the atom so pass through a cavity resonator. CONSTITUTION:An optical switch and an optical switch 11' are inserted into an optical path of the stimulating light from stimulating lasers 2, 2', and an optical path of the stimulating light from a stimulating laser 4, respectively, and also, a timing signal generator 12 for bringing the optical switches 11, 11' to ON/OFF control is provided. The timing signal generator 12 turns ON the switch during the time tau, and subsequently, turns it OFF during the time T, and repeats this control. In this case, the time tau is equal to the time required for allowing an atom of the highest speed contained in an atomic beam to pass through the stimulating part, that is, the time when the atom is irradiated by light from the stimulating lasers 2, 2', and the time T is equal to the time required for allowing its atom to pass through a cavity resonator 3. Consequently, a time/frequency standard whose frequency accuracy is excellent is obtained.

Description

[Detailed Description of the Invention] "Field of Industrial Application" The present invention relates to an atomic beam oscillator used, for example, to generate a standard clock for network synchronization. Related to atomic beam resonator.

``Prior art'' The optical bombing type atomic beam oscillator is an oscillator that obtains an extremely stable frequency by stabilizing the oscillation frequency of a crystal oscillator based on the transition frequency between electronic energy levels in the ultrafine structure of a cesium atom. It is.

FIG. 3 shows the configuration of a conventional optical bombing type atomic beam oscillator. The atomic beam emitted from the atomic beam generating reactor 1 reaches the cavity resonator 3 after being brought to a certain level of electron energy by the laser light emitted from the excitation laser 2.2'. The cavity resonator 3 is excited by microwaves, and atoms that reach this cavity resonator 3 interact with the microwaves and undergo induced transition. The atoms that have undergone induced transition are excited by the laser light emitted from the excitation laser 4 and emit fluorescence. This fluorescence is converted into an electrical signal by the photodetector 5 and then output to the synchronous detector 7. The synchronous detector 7 synchronously detects the output of the photodetector 5 using the output of the low frequency oscillator 6 as a reference signal.

This detection output indicates that the microwave frequency of the cavity resonator 3 is the transition frequency ν of the cesium atom. (9,19G+-1z)
This is a signal that becomes "0" when it matches the , and is output to the VCO (i-pressure controlled oscillator) control section 8 . The VCO control unit 8 is
Based on the output of the synchronous detector 7, the frequency of the microwave of the cavity resonator 3 is ν. The oscillation frequency of the VCO 9 is controlled so that The output of this VCO 9 is output to the outside as an oscillator output, and is also multiplied by a frequency multiplier 13 to have a frequency ν. is converted into a microwave and output to the cavity resonator 3 via the phase modulator IO.

"Problems to be Solved by the Invention" The optical bombing type atomic beam oscillator described above has the drawbacks of the conventional magnetic field deflection type atomic beam oscillator, such as low atomic utilization efficiency, frequency offset caused by the magnetic field, and complicated atomic orbits. This problem can be solved, and frequency stability and accuracy can be significantly improved. However, if part of the fluorescence generated when the atoms interact with the excitation light enters the cavity resonator 3, the energy level of the atoms will change due to this fluorescence, and the resonance frequency will also shift. This is called a light shift (e.g. ^, Br1ll
et, “Evaluation or the lig
ht 5hirts in an optically
pumped cesium beam
ency 5 standard.

"Metrologia, 17. pp, 147-
150.1981). The amount of shift is proportional to the intensity of fluorescence in the cavity resonator 3. Therefore, by increasing the distance between the region where atoms and excitation light interact and the cavity resonator 3, the amount of shift can be reduced in inverse proportion to the distance. However, if the distance between the region where the atoms and the excitation light interact and the cavity resonator 3 is increased, the device becomes larger.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an atomic beam resonator in which optical shift is fundamentally eliminated and frequency accuracy is improved.

"Means for Solving the Problems" The present invention provides a cavity resonator that resonates atoms at a predetermined electronic energy level using microwaves, and an atomic beam generator that supplies an atomic beam to the cavity resonator. a reactor, and generates excitation light for irradiating the atomic beam before entering the cavity resonator to excite the predetermined electron energy level and irradiating the atomic beam after exiting the cavity resonator. In the atomic beam resonator apparatus, the atomic beam resonator includes an excitation laser that emits from the cavity resonator and detects fluorescence from an atomic beam excited by the excitation light, in which the atoms in the atomic beam are excited by the excitation light. The present invention is characterized in that an optical switch means is provided for repeatedly turning on and off the excitation light depending on the time required for the atom to pass through the part and the time required for the atom to pass through the cavity resonator.

"Operation" In the present invention, while atoms at a certain electronic energy level are traveling in the cavity, excitation light is blocked to prevent fluorescence from entering the cavity. , this fundamentally eliminates optical software. According to such a configuration, it is possible to improve the frequency accuracy of the atomic beam oscillator without increasing the size of the device.

Embodiment FIG. 1 is a block diagram showing the configuration of an optical bombing type atomic beam oscillator using an atomic beam resonator according to an embodiment of the present invention. The same reference numerals are used to omit the explanation.The atomic beam oscillator shown in this figure is different from the one shown in FIG. 11, optical switches 11° are also inserted in the optical path of the excitation light from the excitation laser 4,
Further, a timing signal generator 12 is provided which generates a control signal for controlling on/off the optical switches 11, 11°.

Here, the timing signal generator 12 is the optical switch 11
, 1.1° are controlled on/off at the timing shown in FIG. That is, it is turned on for a time τ, then turned off for a time T, and this control is repeated.

In this case, the time τ is the time required for an atom with the most probable velocity included in the atomic beam to pass through the excitation light section, that is,
The time T is equal to the time during which the atom is irradiated with the light from the excitation lasers 2, 2', and the time T is equal to the time required for the atom to pass through the cavity resonator 3.

In such a configuration, first, when the light opening switches t + and t t' at time τ are turned on, light from the laser 2°2° irradiates the atomic beam. Next, during the time T during which the atoms, which have reached a certain electronic energy level due to the above-mentioned light irradiation, pass through the cavity' (oscillator 3), the optical switch +1.11'
is turned off. Therefore, the atoms pass through the cavity resonator 3 without any optical shift, and at this time, the atoms undergo induced transition at the resonant frequency.

Next, the optical switch 11.11' is turned on again,
The atoms that have passed through the cavity resonator 3 are excited by the laser light from the laser 4 and emit fluorescence.

At this time, ■CO control unit 8 also becomes operational, and this VCO
The control unit 8 controls the oscillation frequency of the VCO 9 .

At this time, atomic beam irradiation is simultaneously performed by the laser light from the laser 2.2, and the above operation is repeated thereafter.

"Effects of the Invention" As explained above, according to the present invention, it is possible to completely eliminate the optical shift in the cavity resonator, thereby realizing a time/frequency standard with excellent frequency accuracy. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical bombing type atomic beam oscillator to which an atomic beam resonator according to an embodiment of the present invention is applied, and FIG. 2 is an optical switch 1 in the same embodiment.
FIG. 3 is a block diagram showing an example of the configuration of a conventional optical pumping type atomic beam oscillator. l... Atomic beam generator, 2.2°...
Excitation laser, 3...Cavity resonator, 4...
・Excitation laser, 5...Photodetector, 11.11
'...Optical switch, 12...Timing signal generator. Figure 3

Claims (1)

[Claims] A cavity resonator that resonates atoms at a predetermined electronic energy level using microwaves, an atomic beam generator that supplies an atomic beam to the cavity resonator, and atoms before entering the cavity resonator. an excitation laser that irradiates a beam to excite the electrons to the predetermined energy level and generates excitation light for irradiating the atomic beam after exiting the cavity resonator; and a photodetector for detecting fluorescence from the atomic beam excited by the excitation light, the time required for the atoms in the atomic beam to pass through the excitation light portion and the time required for the atoms to pass through the excitation light portion, An atomic beam resonator comprising an optical switch means for repeatedly turning on and off the excitation light depending on the time required for the excitation light to pass through a body resonator.