ATOMIC OSCILLATOR AND METHOD FOR FABRICATING ATOMIC OSCILLATOR

• US 20130015920A1
• Filed: 07/11/2012
• Published: 01/17/2013
• Est. Priority Date: 07/13/2011
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: SATO, Shunichi, ITOH, Akihiro, SATO, Yukito
• Granted Patent: US 8,970,309 B2
• Time in Patent Office: Days
• US Class Current: 331/94.1
• CPC Class Codes: G04F 5/14 using atomic clocks
• CPC Class Codes: H03L 7/26 using energy levels of molecules, atoms, or subatomic particles as a frequency reference
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

An atomic oscillator is disclosed, including an Alkaline metal cell, a light source illuminating a laser beam to the Alkaline metal cell, and a light detector detecting light passing through the Alkaline metal cell. The Alkaline metal cell includes a first member, a second member, a cell internal portion, and an Alkaline metal raw material. In the first member, a first glass substrate is bonded on a second surface of a first substrate where a first opening part is formed. In the second member, a second glass substrate is bonded to a fourth surface of a second substrate where a second opening part is formed. The cell internal portion is formed by the first opening part and the second opening part by bonding the first surface to the third surface. The Alkaline metal raw material is enclosed by the cell internal portion.

Claims

1. An atomic oscillator including an Alkaline metal cell in which the Alkaline metal is sealed, a light source which illuminates a laser beam to the Alkaline metal cell, and a light detector which detects light passing through the Alkaline metal cell, wherein the Alkaline metal cell comprises:

a first member in which a first glass substrate is bonded on a second surface of a first substrate where a first opening part is formed to penetrate from a first surface to the second surface;

a second member in which a second glass substrate is bonded to a fourth surface of a second substrate where a second opening part is formed to penetrate from a third surface to the fourth surface;

a cell internal portion which is formed by the first opening part of the first member and the second opening part of the second member by bonding the first surface of the first substrate in the first member to the third surface of the second substrate in the second member, and

an Alkaline metal raw material which is enclosed by the cell internal portion.

2. The atomic oscillator as claimed in claim 1, wherein the first surface of the first substrate in the first member and the third surface of the second substrate in the second member are bonded due to direct bonding.

3. The atomic oscillator as claimed in claim 1, wherein a metal film is further formed on one of or both of the first surface of the first substrate in the first member and the third surface of the second substrate in the second member;

and

the first surface of the first substrate in the first member and the third surface of the second substrate in the second member are bonded due to eutectic bonding through the metal film or direct bonding of metals.

4. The atomic oscillator as claimed in claim 1, wherein a glass frit is further provided on one of or both of the first surface of the first substrate in the first member and the third surface of the second substrate in the second member;

and

the first surface of the first substrate in the first member and the third surface of the second substrate in the second member are bonded due to bonding through the glass frit.

5. The atomic oscillator as claimed in claim 1, wherein the first substrate and the second substrate are formed by silicon.

6. The atomic oscillator as claimed in claim 1, comprising:

at least one third substrate which is provided between the first member and the second member, the at least one third substrate including a third opening part having approximately the same shape as shapes of the first opening part and the second opening part, wherein,

the first member is bonded to the at least one third substrate and the second member is bonded to the at least one third substrate; and

the cell internal portion is formed by the first opening part of the first member, the second opening part of the second member, and the third opening part of the at least one third substrate.

7. The atomic oscillator as claimed in claim 5, wherein a distance between the first glass substrate and the second glass substrate is greater than or equal to 1.5 mm.

8. The atomic oscillator as claimed in claim 1, wherein

the cell internal portion includes a first cell internal portion and a second cell internal portion;

the first cell internal portion is connected to the second cell internal portion by a cell connection part;

the Alkaline metal raw material is a chemical compound of Alkaline metal, and is arranged in the second cell internal portion; and

light illuminated from the light source passes the first cell internal portion.

9. The atomic oscillator as claimed in claim 1, wherein the atomic oscillator controls modulation frequency by a light absorption feature due to a quantum interference effect caused by two types of resonance light, by controlling two lights having different wavelengths to enter the Alkaline metal cell including sidebands emitted from the light source.

10. A method for fabricating an atomic oscillator which includes an Alkaline metal cell in which the Alkaline metal is sealed, a light source which illuminates a laser beam onto the Alkaline metal cell, and a light detector which detects light passing through the Alkaline metal cell, said method comprising:

forming a first opening part which penetrates from a first surface to a second surface of a first substrate and an second opening part which penetrates from a third surface to a fourth surface of a second substrate, the first opening part and the second opening part having approximately the same shape;

forming a first member by bonding a first glass substrate to the second surface of the first substrate where the first opening part is formed, and a second member by bonding a second glass substrate to the fourth surface of the second substrate where the second opening part is formed;

inputting an Alkaline metal raw material into the first opening part of the first member or the second opening part of the second member; and

bonding a first surface of the first substrate of the first member to a third surface of the second substrate of the second member,

wherein a cell internal portion of the Alkaline metal cell is formed by the first opening part of the first member and the second opening part of the second member.

11. The method as claimed in claim 10, wherein

the first substrate and the second substrate are formed by silicon;

and

the first member and the second member are bonded by direct bonding of the silicon.

12. The method as claimed in claim 10, further comprising:

forming a third opening part which is approximately the same shape as the first and second opening parts and penetrates from a fifth surface to a sixth surface in at least one third substrate,

wherein in the bonding the first member to the second member, the first surface of the first substrate of the first member is bonded to the third surface of the second substrate of the second member through the at least one third substrate.

13. The method as claimed in claim 10, wherein

a metal film is formed onto one of or both of the first surface of the first substrate of the first member and the third surface of the second substrate of the second member;

and

the first member is bonded to the second member by eutectic bonding through the metal film or direct bonding of metals.

14. The method as claimed in claim 10, wherein

a glass frit is formed on one of or both of the first surface of the first substrate of the first member and the third surface of the second member of the second member, and

the first member is bonded to the second member through the glass frit.

15. The method as claimed in claim 10, wherein

the Alkaline metal raw material is a chemical compound of the Alkaline metal;

and

after the cell internal portion is formed, the Alkaline metal is generated by heating the Alkaline metal raw material, illuminating ultraviolet light, and illuminating the laser beam.

16. The method as claimed in claim 10, wherein

the cell internal portion includes a first cell internal portion and a second cell internal portion;

the first cell internal portion is connected to the second cell internal portion by the cell connection part;

the Alkaline metal raw material is a chemical compound of the Alkaline metal, and is arranged in the second cell internal portion; and

the Alkaline metal is generated by heating the Alkaline metal raw material, illuminating ultraviolet light, and illuminating the laser beam, so that the Alkaline metal enters the first cell internal portion.

17. The method as claimed in claim 16, further comprising spatially separating the first cell internal portion and the second cell internal portion by sealing the cell connection part after moving the Alkaline metal into the first cell internal portion.

18. The method as claimed in claim 17, wherein the cell connection part is sealed by heating the glass frit.

19. The method as claimed in claim 11, wherein

the inputting the Alkaline metal raw material and the bonding the first member to the second member are conducted in a vacuum chamber;

and

the method further includes conducting an activation process with respect to bonding surfaces by illuminating plasma onto the bonding surfaces for bonding the first member to the second member in the vacuum chamber, before the bonding the first member to the second member.

20. The method as claimed in claim 10, wherein the bonding the first member to the second member is performed in an atmosphere of Nitrogen or an inert gas in the vacuum chamber.