# US 12,119,832 B2 · Atomic oscillator

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- Number: US 12,119,832 B2
- Document ID: US12119832B2
- Status: Granted
- Kind: B2
- Application number: 18/101,737
- Filed: 2023-01-26
- Published: 2023-10-05
- Granted: 2024-10-15
- Earliest claimed: 2022-03-30
- Assignees: NEC Corporation
- Applicants: NEC Corporation
- Inventors: Sota Kagami
- Web page: https://patentgrep.com/patent/US12119832B2

## CPC

- G04F 5/145: {using Coherent Population Trapping}
- H03L 7/26: using energy levels of molecules, atoms, or subatomic particles as a frequency reference
- G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S)
- H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B)

## Abstract

An atomic oscillator according to the present invention includes an alkali metal cell, a light source configured to emit excitation light to the alkali metal cell, and a photodetector configured to detect transmission light passed through the alkali metal cell. In the atomic oscillator, a light absorber and a light radiator are placed. The light absorber is configured to raise a temperature thereof in accordance with absorption light to heat the alkali metal cell in contact with the alkali metal cell. The light radiator is configured to radiate light corresponding to heat of the alkali metal cell in contact therewith. The atomic oscillator further includes a second light source configured to emit light to the light absorber, and a second photodetector configured to detect the light radiated by the light radiator.

## Claims

### Claim 1

An atomic oscillator comprising: an alkali metal cell; a light source configured to emit excitation light to the alkali metal cell; and a photodetector configured to detect transmission light passed through the alkali metal cell,
wherein a light absorber and a light radiator are placed, the light absorber being configured to raise a temperature thereof in accordance with absorption light to heat the alkali metal cell in contact with the alkali metal cell, the light radiator being configured to radiate light corresponding to heat of the alkali metal cell in contact therewith,
the atomic oscillator further comprising: a second light source configured to emit light to the light absorber; and a second photodetector configured to detect the light radiated by the light radiator.

### Claim 2 (depends on 1)

The atomic oscillator according to claim 1, wherein
the light absorber and the light radiator are each formed of a film member attached to a face of the alkali metal cell.

### Claim 3 (depends on 1)

The atomic oscillator according to claim 1, wherein
the light absorber and the light radiator are each formed of black body paint applied to a face of the alkali metal cell.

### Claim 4 (depends on 1)

The atomic oscillator according to claim 1, wherein
the light absorber is formed of a member having a higher absorptivity to the light emitted by the second light source than to the light emitted by the light source.

### Claim 5 (depends on 1)

The atomic oscillator according to claim 1, wherein
the light absorber is formed to be larger in size than the light radiator.

### Claim 6 (depends on 1)

The atomic oscillator according to claim 1, wherein
the second light source is configured to emit light having a shorter wavelength than light that can be detected by the second photodetector.

### Claim 7 (depends on 1)

The atomic oscillator according to claim 1, comprising
a control unit configured to detect a temperature of the alkali metal cell based on the light detected from the second photodetector, and control the light emitted by the second light source based on the detected temperature.

### Claim 8

A method for controlling an atomic oscillator, the atomic oscillator including: an alkali metal cell; a light source configured to emit excitation light to the alkali metal cell; and a photodetector configured to detect transmission light passed through the alkali metal cell,
the method comprising:
emitting light to a light absorber placed in contact with the alkali metal cell and configured to raise a temperature thereof in accordance with absorption light to heat the alkali metal cell, from a second light source that is different from the light source; and
detecting light radiated from a light radiator placed in contact with the alkali metal cell and configured to radiate light corresponding to heat of the alkali metal cell in contact therewith, by a second photodetector that is different from the photodetector.

### Claim 9 (depends on 8)

The method for controlling the atomic oscillator according to claim 8, comprising
detecting a temperature of the alkali metal cell based on the light detected from the second photodetector, and controlling the light emitted from the second light source based on the detected temperature.

### Claim 10

A control apparatus controlling an operation of an atomic oscillator, the atomic oscillator including: an alkali metal cell; a light source configured to emit excitation light to the alkali metal cell; and a photodetector configured to detect transmission light passed through the alkali metal cell, the control apparatus being configured to:
emit light to a light absorber placed in contact with the alkali metal cell and configured to raise a temperature thereof in accordance with absorption light to heat the alkali metal cell, from a second light source that is different from the light source; and
detect light radiated from a light radiator placed in contact with the alkali metal cell and configured to radiate light corresponding to heat of the alkali metal cell in contact therewith, by a second photodetector that is different from the photodetector.