WO2016038990A1

WO2016038990A1 - Resonator, light source device and frequency filter

Info

Publication number: WO2016038990A1
Application number: PCT/JP2015/068891
Authority: WO
Inventors: 真美子鯨岡; 市村　厚一; 隼人後藤; 悟史中村
Original assignee: 株式会社東芝
Priority date: 2014-09-08
Filing date: 2015-06-30
Publication date: 2016-03-17
Also published as: JPWO2016038990A1; JP6253793B2

Abstract

A resonator according to one embodiment of the present invention comprises a first mirror, a second mirror, a first spacer and a second spacer. The first spacer is arranged between the first mirror and the second mirror, and is in contact with the first mirror. The second spacer is arranged between the first spacer and the second mirror, and is in contact with the second mirror. A first resonator length which is formed of the first mirror and the second mirror in a first state wherein the first spacer and the second spacer are in contact with each other is different from a second resonator length which is formed of the first mirror and the second mirror in a second state which is different from the first state and wherein the first spacer and the second spacer are in contact with each other.

Description

Resonator, light source device, and frequency filter

Embodiments of the present invention relate to a resonator, a light source device, and a frequency filter.

The resonator is used in fields such as high resolution spectroscopy and optical communication, for example. A light source having a stable frequency can be obtained by locking the frequency to a resonator having high frequency stability. The resonator is also used as a frequency filter. In order to enhance practicality in application fields such as spectroscopy and optical communication, a resonator having a variable resonance frequency is desired.

Japanese Patent Laid-Open No. 9-129957

Embodiments of the present invention provide a resonator having a variable resonance frequency, a light source device, and a frequency filter.

According to the embodiment of the present invention, the resonator includes a first mirror, a second mirror, a first spacer, and a second spacer. The first spacer is provided between the first mirror and the second mirror and is in contact with the first mirror. The second spacer is provided between the first spacer and the second mirror and is in contact with the second mirror. The first resonator length formed by the first mirror and the second mirror in a first state where the first spacer and the second spacer are in contact with each other is such that the first spacer and the second spacer are The second resonator length formed by the first mirror and the second mirror in a second state that is in contact and different from the first state is different.

FIG. 1A to FIG. 1E are schematic views showing a resonator according to the first embodiment. 1 is a schematic cross-sectional view showing a resonator according to a first embodiment. FIG. 3A and FIG. 3B are schematic views showing the resonator according to the first embodiment. FIG. 4A and FIG. 4B are schematic views showing another resonator according to the first embodiment. FIGS. 5A to 5F are schematic views showing another resonator according to the first embodiment. FIG. 6A and FIG. 6B are schematic views showing another resonator according to the first embodiment. FIG. 7A to FIG. 7D are schematic views showing another resonator according to the first embodiment. FIG. 8A to FIG. 8D are schematic perspective views showing the resonator according to the first embodiment. FIG. 9A and FIG. 9B are schematic views showing another resonator according to the first embodiment. FIG. 10A and FIG. 10B are schematic views showing another resonator according to the first embodiment. FIG. 11A and FIG. 11B are schematic views showing another resonator according to the first embodiment. FIG. 12A and FIG. 12B are schematic views illustrating a resonator according to the second embodiment. FIG. 13A and FIG. 13B are schematic views showing another resonator according to the second embodiment. FIG. 14A to FIG. 14D are schematic views showing another resonator according to the second embodiment. FIG. 15A and FIG. 15B are schematic views showing the resonator according to the embodiment. FIG. 16A and FIG. 16B are schematic views showing the resonator according to the embodiment. FIG. 17A and FIG. 17B are schematic views showing the resonator according to the embodiment. FIG. 18A and FIG. 18B are schematic views showing the resonator according to the embodiment. It is a schematic diagram which shows the resonator which concerns on embodiment. FIG. 20A and FIG. 20B are schematic views illustrating the resonator according to the embodiment. FIG. 21A and FIG. 21B are schematic views illustrating the resonator according to the embodiment. It is a schematic diagram which shows the light source device which concerns on 3rd Embodiment. It is a schematic diagram which shows another light source device which concerns on 3rd Embodiment. It is a schematic diagram which shows the frequency filter which concerns on 4th Embodiment. FIG. 25A to FIG. 25F are schematic views showing a resonator according to the fifth embodiment. FIG. 26A to FIG. 26D are schematic views showing another resonator according to the fifth embodiment. FIG. 27A and FIG. 27B are schematic views showing another resonator according to the fifth embodiment. FIG. 28A and FIG. 28B are schematic views showing another resonator according to the fifth embodiment. FIG. 29A to FIG. 29D are schematic views showing another resonator according to the sixth embodiment. FIG. 30A to FIG. 30D are schematic views showing another resonator according to the sixth embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1A to FIG. 1E are schematic views illustrating the resonator according to the first embodiment.
FIG. 2 is a schematic cross-sectional view illustrating the resonator according to the first embodiment.
FIG. 1A is a schematic perspective view. FIG. 1B is a schematic perspective view illustrating elements included in the resonator separately. FIG. 1C and FIG. 1D are schematic cross-sectional views. FIG.1 (e) is a top view from the arrow Ar direction shown to Fig.1 (a).

As shown in FIG. 1A, the resonator 110 according to the embodiment includes a first mirror 10, a second mirror 20, a first spacer 50, a second spacer 60, and a control unit 30. . In this example, a fixing portion 81 is further provided.

As shown in FIG. 2, the resonator 110 may include a container 80. In the container 80, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30 are arranged. The inside of the container 80 is decompressed, for example. The influence of external heat and atmospheric pressure is suppressed, and the resonator length expansion and contraction of the resonator is suppressed. The container 80 may be provided with a temperature adjustment element 82. The temperature of the resonator 110 is adjusted to a desired temperature by the temperature adjustment element 82.

In FIG. 1B, the control unit 30 and the fixing unit 81 are omitted. FIG. 1C illustrates the second mirror 20. FIG. 1D illustrates the first mirror 10.

As shown in FIGS. 1A and 1B, the second mirror 20 faces the first mirror 10. The first mirror 10 has a first mirror surface 10a. The second mirror 20 has a second mirror surface 20a. The first mirror surface 10a and the second mirror surface 20a face each other. The first mirror 10 and the second mirror 20 form, for example, a Fabry-Perot optical resonator.

As will be described later, the spatial arrangement between the first mirror 10 and the second mirror 20 is variable. For example, in one state (for example, the first state), the direction connecting the first mirror 10 and the second mirror 20 is the Z-axis direction. One direction perpendicular to the Z-axis direction is taken as an X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis direction.

The first spacer 50 is provided between the first mirror 10 and the second mirror 20. The first spacer 50 is connected to the outer edge portion 10 r of the first mirror 10. In the embodiment, at least a part of the first spacer 50 may be provided between the first mirror 10 and the second mirror 20. The first spacer 50 may be connected to at least a part of the outer edge portion 10r of the first mirror 10.

The first spacer 50 has, for example, a tubular shape (frame shape) whose axis is the Z-axis direction (a first direction connecting the first mirror 10 in the first state and the second mirror 20 in the first state). The first spacer 50 may have a plurality of portions extending in the Z-axis direction. The first spacer 50 may be connected to the first mirror 10 discontinuously by a plurality of portions.

The second spacer 60 is provided between the first spacer 50 and the second mirror 20. The second spacer 60 is connected to the outer edge portion 20 r of the second mirror 20. In the embodiment, at least a part of the second spacer 60 may be provided between the first spacer 50 and the second mirror 20. The second spacer 60 may be connected to at least a part of the outer edge portion 20r of the second mirror 20. The second spacer 60 has a tubular shape (frame shape) with the Z-axis direction as an axis, for example. The second spacer 60 may have a plurality of portions extending in the Z-axis direction. The second spacer 60 may be connected to the second mirror 20 discontinuously by a plurality of portions. A thin layer of lubricating oil or the like may be inserted between the first spacer 50 and the second spacer 60. Also in this case, the first spacer 50 and the second spacer 60 are substantially in contact with each other.

In this example, the outer shape (planar shape) of the first mirror 10 and the second mirror 20 projected onto the XY plane is a quadrangle. Each outer shape (planar shape) when the first spacer 50 and the second spacer 60 are projected onto the XY plane is a square tube. In the embodiment, the planar shape of the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer 60 may be a polygon other than a square, a circle (including a flat circle), or any other shape. .

For example, light reflected by the first mirror surface 10a and the second mirror surface 20a passes through cavities provided in the first spacer 50 and the second spacer 60, respectively. The light reflected by the first mirror surface 10 a and the second mirror surface 20 a does not pass through the first spacer 50 and the second spacer 60.

The set of the first mirror 10 and the first spacer 50 and the set of the second mirror 20 and the second spacer 60 can be interchanged with each other.

In this example, the first mirror 10 is a concave mirror. That is, the first mirror surface 10a is concave. In this example, the second mirror 20 is a plane mirror. That is, the second mirror surface 20a is planar. As will be described later, the first mirror surface 10a and the second mirror surface 20a can be variously modified.

As illustrated in FIG. 1D, the first mirror 10 includes a plurality of first layers 17 and a plurality of second layers 18. The first layer 17 and the second layer 18 are alternately arranged along the Z-axis direction.

As illustrated in FIG. 1C, the second mirror 20 includes a plurality of third layers 27 and a plurality of fourth layers 28. The third layer 27 and the fourth layer 28 are alternately arranged along the Z-axis direction.

The refractive index of the first layer 17 is different from the refractive index of the second layer 18. The refractive index of the third layer 27 is different from the refractive index of the fourth layer 28. For these layers, for example, a dielectric is used. Each of the first mirror 10 and the second mirror 20 includes, for example, a dielectric multilayer film. The embodiment is not limited to this, and any reflector can be used as the first mirror 10 and the second mirror 20.

As shown in FIG. 1A, the fixing portion 81 is connected to the first spacer 50. The fixing portion 81 is fixed to the container 80, for example. Thereby, the spatial position of the first spacer 50 is fixed.

As shown in FIGS. 1A and 1E, a state in which the control unit 30 is in contact with the second spacer 60 can be formed. In this example, first to fourth moving devices 31 to 34 are used as the control unit 30.

The second spacer 60 is disposed between the first moving device 31 and the second moving device 32. A second spacer 60 is disposed between the third moving device 33 and the fourth moving device 34. In the initial state, these moving devices are separated from the second spacer 60. For example, the first moving device 31 pushes and moves the second spacer 60. Thereby, the second spacer 60 moves in the + X axis direction, for example. For example, the second moving device 32 pushes and moves the second spacer 60. As a result, the second spacer 60 moves in the −X axis direction, for example. For example, during movement, the moving device is in contact with the second spacer 60. After the movement, the moving device moves away from the second spacer 60. Since the moving device is separated from the second spacer 60 after the movement, the influence of the moving device is not exerted on the spacer in the state after the movement. A stable resonator length can be obtained. Similarly, the second spacer 60 is movable along the Y-axis direction by the operations of the third moving device 33 and the fourth moving device 34. In the embodiment, the moving device is allowed to be connected to the second spacer 60.

Each of the first to fourth moving devices 31 to 34 may include first to fourth micrometer heads 31a to 34a and first to fourth piezo actuators 31b to 34b. For example, a piezo actuator is disposed between the micrometer head and the second spacer 60. In the micrometer head, a large position change can be caused. In a piezo actuator, it is possible to cause a change in position with high accuracy. The second spacer 60 can be moved with high accuracy.

The direction of movement of the second spacer 60 intersects with the Z-axis direction, for example.

1A and 1B, the first spacer 50 has a first surface 50a, and the second spacer 60 has a second surface 60a. The first surface 50 a faces the second spacer 60. The second surface 60 a faces the first spacer 50. The second surface 60a faces the first surface 50a. The second surface 60a is along the first surface 50a.

In this example, the first surface 50a intersects the Z-axis direction (first direction). The Z-axis direction is a direction connecting the first mirror 10 in one state (first state) and the second mirror 20 in that state (first state). The first surface 50a is inclined with respect to the Z-axis direction. The second surface 60a along the first surface 50a is also inclined with respect to the Z-axis direction.

The position of the second spacer 60 is changed by the operation of the control unit 30. In the second spacer 60 before movement, the second surface 60a is in contact with the first surface 50a. In the second spacer 60 after movement, the second surface 60a is in contact with the first surface 50a. The second spacer 60 may move while the second surface 60a is in contact with the first surface 50a. Due to the movement, the resonator length of the resonator formed by the first mirror 10 and the second mirror 20 changes. Hereinafter, an example of a change in the resonator length will be described.

FIG. 3A and FIG. 3B are schematic views illustrating the resonator according to the first embodiment. FIGS. 3A and 3B illustrate the first state ST1 and the second state ST2 provided in the resonator 110, respectively. In these drawings, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30 are illustrated, and other elements are omitted.

As shown in FIG. 3A, in the first state ST1, the first spacer 50 and the second spacer 60 are in contact with each other. In the first state ST 1, the position of the second spacer 60 is set to a first position relative to the first spacer 50. At this time, the first resonator Rs1 is formed by the first mirror 10 and the second mirror 20. This resonator has a first resonator length L1. In this example, the first mirror 10 is a concave mirror. The first mirror 10 has, for example, the spherical center of the concave mirror (first center 10c). The first resonator length L1 corresponds to the distance between the first mirror 10 and the second mirror 20 on a straight line passing through the first center 10c and perpendicular to the second mirror surface 20a in the first state ST1. To do. Thus, in the first state ST1, the first mirror 10 and the second mirror 20 form the first resonator length L1.

As shown in FIG. 3B, the first spacer 50 and the second spacer 60 are in contact with each other even in the second state ST2. In the second state ST2, the second spacer 60 is moved with respect to the first state ST1 by the operation of the control unit 30. The first state ST1 and the second state ST2 are reversible.

The position of the second state ST2 is a position different from the first state ST1. In the second state ST 2, the second spacer 60 is set at a second position relative to the first spacer 50. The second position is different from the first position. At this time, the first resonator 10 and the second mirror 20 form a second resonator Rs2. This resonator has a second resonator length L2. The second resonator length L2 corresponds to the distance between the first mirror 10 and the second mirror 20 on a straight line passing through the first center 10c and perpendicular to the second mirror surface 20a in the second state ST2. To do. Thus, the control unit 30 causes the first resonator 10 and the second mirror 20 to form the second resonator length L2 in the second state ST2. The second resonator length L2 is different from the first resonator length L1. In this example, the second resonator length L2 is shorter than the first resonator length L1.

The first position (relative position of the second spacer 60 with respect to the first spacer 50 in the first state ST1) and the second position (relative of the second spacer 60 with respect to the first spacer 50 in the second state ST2). The direction that connects to the Z-axis direction has a component that intersects the Z-axis direction. That is, the direction connecting the first position and the second position intersects the first direction connecting the first mirror 10 in the first state ST1 and the second mirror 20 in the first state ST1. For example, the direction connecting the first position and the second position intersects the second direction connecting the first mirror 10 in the second state ST2 and the second mirror 20 in the second state ST2.

The resonator length can be changed by moving the second spacer 60 relative to the first spacer 50 in such a direction. Thereby, the resonant frequency in a resonator can be changed.

The change of the resonance frequency when the resonator length is changed will be described. It is assumed that the resonator length L is changed by the resonator length shift amount ΔL. The frequency shift amount Δν with respect to the original resonance frequency ν is expressed by the following first equation.

Δν / ν = -ΔL / (L + ΔL) (1)

For example, L is the first resonator length L1, and ΔL is the difference between the first resonator length L1 and the second resonator length L2.

Therefore, in the second state ST2 of the second resonator length L2, a resonance frequency different from the resonance frequency of the first state ST1 of the first resonator length L1 is obtained.

The resonator length is the optical length of the resonator mode formed inside the resonator. When two spherical mirrors are provided in a Fabry-Perot optical resonator, a resonator mode is formed on a straight line connecting the centers of the respective spherical surfaces. When a concave mirror and a plane mirror are provided, a resonator mode is formed on a straight line that passes through the center of the spherical surface of the concave mirror and is perpendicular to the plane mirror. When two plane mirrors are provided, the resonator mode is formed on a straight line perpendicular to the plane of the plane mirror. In this case, the two planes are strictly parallel.

In the embodiment, the configuration in which the resonator length is changed in the first state ST1 and the second state ST2 can be variously modified.

When the concave mirror and the plane mirror are provided, for example, as illustrated in FIGS. 3A and 3B, the second spacer 60 is moved along the direction inclined with respect to the plane of the plane mirror. Move relative to the spacer 50. As a result, the resonator length changes.

FIG. 4A and FIG. 4B are schematic views illustrating another resonator according to the first embodiment.
These drawings illustrate another resonator 111 according to this embodiment. In these drawings, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30 are illustrated, and other elements are omitted. FIGS. 4A and 4B illustrate a first state ST1 and a second state ST2 provided in the resonator 111, respectively.

Also in the resonator 111, the first mirror 10 is a concave mirror, and the second mirror 20 is a plane mirror. The mirror surface (second mirror surface 20a) of the second mirror 20 is a flat surface. The second mirror surface 20a is inclined with respect to the Z-axis direction.

Also in this case, the first resonator length L1 is formed in the first state ST1, and the second resonator length L2 is formed in the second state ST2. The second resonator length L2 is different from the first resonator length L1. In this example, the first surface 50a and the second surface 60a are perpendicular to the Z-axis direction. In this case, the direction of movement of the second spacer 60 (the direction of change in the position relative to the first spacer 50) is perpendicular to the Z-axis direction.

When a concave mirror and a plane mirror are used, the direction of movement may be any direction having a component that intersects the Z-axis direction.

FIG. 5A to FIG. 5F are schematic views illustrating another resonator according to the first embodiment.
FIGS. 5A and 5B illustrate the first state ST1 and the second state ST2 in the resonator 112a. FIG. 5C and FIG. 5D illustrate the first state ST1 and the second state ST2 in the resonator 112b. FIGS. 5E and 5F illustrate the first state ST1 and the second state ST2 in the resonator 112c. In these drawings, the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer 60 are shown, and other elements are omitted.

In the resonators 112a to 112c, the first mirror surface 10a of the first mirror 10 and the second mirror surface 20a of the second mirror 20 are concave mirrors. The second mirror 20 has, for example, the spherical center of the concave mirror (second center 20c). The resonator length corresponds to the distance between the first mirror 10 and the second mirror 20 on the straight line connecting the first center 10c and the second center 20c.

In the resonator 112a, the first surface 50a of the first spacer 50 and the second surface 60a of the second spacer 60 are perpendicular to the Z-axis direction. In the resonator 112b, the first surface 50a and the second surface 60a are curved. In the resonator 112c, the first surface 50a and the second surface 60a are inclined with respect to the Z-axis direction.

In such resonators 112a to 112c, the second spacer 60 is relatively moved while being in contact with the second spacer 50, so that the resonator length can be increased between the first state ST1 and the second state ST2. Can be changed.

FIG. 6A and FIG. 6B are schematic views illustrating another resonator according to the first embodiment.
These drawings illustrate the first state ST1 and the second state ST2 in the resonator 113. In these drawings, the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer 60 are shown, and other elements are omitted.

In the resonator 113, the first mirror 10 is a plane mirror, and the second mirror 20 is also a plane mirror.

The first surface 50a and the second surface 60a are inclined with respect to the Z-axis direction. The second spacer 60 moves with the second surface 60a in contact with the first surface 50a. The direction of movement intersects the Z-axis direction. Thereby, the resonator length of the resonator formed by the first mirror 10 and the second mirror 20 changes.

FIG. 7A to FIG. 7D are schematic views illustrating another resonator according to the first embodiment.
FIGS. 7A and 7B illustrate the first state ST1 and the second state ST2 in the resonator 114a. FIG. 7C and FIG. 7D illustrate the first state ST1 and the second state ST2 in the resonator 114b. In these drawings, the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer 60 are shown, and other elements are omitted.

In the

resonators

114a and 114b, the first mirror 10 is a convex mirror and the second mirror 20 is a concave mirror. That is, the first mirror surface 10a is convex, and the second mirror surface 20a is concave.

In the resonator 114a, the first surface 50a of the first spacer 50 and the second surface 60a of the second spacer 60 are perpendicular to the Z-axis direction. In the resonator 112b, the first surface 50a and the second surface 60a are inclined with respect to the Z-axis direction.

In

such resonators

114 a and 114 b, the second spacer 60 is moved relative to the first spacer 50 while being in contact with the first spacer 50. Thereby, the resonator length can be changed between the first state ST1 and the second state ST2.

Hereinafter, an example of relative movement between the first spacer 50 and the second spacer 60 will be described. Hereinafter, a case where the first spacer 50 (and the first mirror 10) is fixed and the second spacer 60 (and the second mirror 20) is moved will be described.

FIG. 8A to FIG. 8D are schematic perspective views illustrating the resonator according to the first embodiment.
FIG. 8A illustrates the first state ST1. FIG. 8B to FIG. 8D illustrate three types of second states ST2.
In this example, the first mirror 10 is a concave mirror, the second mirror 20 is a plane mirror, and the planar shape is a square. A rectangular parallelepiped is formed by the first spacer 50 and the second spacer 60. The first surface 50a and the second surface 60a are inclined with respect to the Z-axis direction. The first surface 50 a and the second surface 60 a are inclined with respect to the respective mirror surfaces of the first mirror 10 and the second mirror 20. Accordingly, the first surface 50a and the second surface 60a are rectangular.

Transition from the first state ST1 shown in FIG. 8A to the second state ST2 shown in FIG. 8B. The moving direction Md of the second spacer 60 is along the long side direction of the rectangle of the first surface 50a and the second surface 60a. In this case, the resonator length changes between the first state ST1 and the second state ST2.

When the moving direction Md of the second spacer 60 is along the rectangular short side direction of the first surface 50a and the second surface 60a, the resonator length is between the first state ST1 and the second state ST2. Does not change.

In the second state ST2 shown in FIG. 8C, the moving direction Md of the second spacer 60 is along the diagonal direction of the rectangles of the first surface 50a and the second surface 60a. In this case, the resonator length changes between the first state ST1 and the second state ST2.

In the second state ST2 shown in FIG. 8D, the moving direction Md of the second spacer 60 includes a rotation component. The axis of rotation includes a component in a direction that intersects the Z-axis direction. In this case, the resonator length changes between the first state ST1 and the second state ST2.

Thus, there are cases where the change (for example, ratio) of the change amount of the resonator length with respect to the movement amount (movement distance) of the second spacer 60 can be changed.

The ratio of the change amount of the resonator length to the movement amount of the second spacer 60 depends on the direction of movement. In some cases, it is desired to obtain a large change in the resonator length with respect to the movement amount of the second spacer 60. On the other hand, there is a case where it is desired to change the resonator length with high accuracy with respect to the movement amount of the second spacer 60. Select the moving direction according to the application. This facilitates changing the resonator length to a desired size and with a desired accuracy.

In the embodiment, the movement in the first spacer 50 and the second spacer 60 is a relative movement. The second spacer 60 may be fixed and the first spacer 50 may move. Each of the first spacer 50 and the sixth spacer 60 may move. That is, it is only necessary to form the first state ST1 and the second state ST2 having different relative positions.

FIG. 9A and FIG. 9B are schematic views illustrating another resonator according to the first embodiment.
These drawings illustrate the first state ST1 and the second state ST2 in the resonator 115.

In the resonator 115, the first mirror 10 is a concave mirror, and the second mirror 20 is a plane mirror. In this example, the first connection portion 51 and the first intermediate portion 52 are provided in the first spacer 50. The first connection unit 51 is connected to the first mirror 10. The first intermediate part 52 is provided between the first connection part 51 and the second spacer 60.

The first connection part 51 has a surface 51 a that faces the first intermediate part 52. The second intermediate part 52 has a surface 52 a that faces the first connection part 51. The surface 52a is along the surface 51a. In this example, the surface 51a and the surface 52a are inclined with respect to the Z-axis direction.

As shown in FIGS. 9A and 9B, the relative position of the second spacer 60 with respect to the first spacer 50 changes between the first state ST1 and the second state ST2. Furthermore, in the first spacer 50, the relative position of the first intermediate portion 52 with respect to the first connection portion 51 is changed. In the first state ST1 and the second state ST2, the first intermediate part 52 is in contact with the first connection part 51. In the first state ST1 and the second state ST2, the first intermediate part 52 is in contact with the second spacer 60.

For example, one direction that intersects the Z-axis direction (a first direction connecting the first mirror 10 in the first state ST1 and the second mirror 20 in the first state ST1) is defined as a first intersecting direction. In this example, the first intersecting direction is the X-axis direction. The position of the first intermediate part 52 in the first intersecting direction can be changed with respect to the position of the first connecting part 51 in the first intersecting direction.

In the resonator 115, in addition to the movement of the second spacer 60, the movement of the first intermediate portion 52 changes the resonator length. For example, the resonator length can be changed greatly.

In this example, the first surface 50a is inclined with respect to the Z-axis direction. The surface 51a (and the surface 52a) is also inclined with respect to the Z-axis direction. In this example, the angle between the first surface 50a and the Z-axis direction is different from the angle between the surface 51a and the Z-axis direction. The change rate of the resonator length with respect to the movement amount of the second spacer 60 is different from the change rate of the resonator length with respect to the movement amount of the first intermediate portion 52. By changing the angles of these surfaces, it is possible to change the resonator length largely and to change it with high accuracy.

The inclination direction of the first surface 50a with respect to the Z-axis direction may be different from the inclination direction of the surface 51a with respect to the Z-axis direction. For example, the first surface 50a may be inclined with respect to the Z-axis direction and the X-axis direction, and the surface 51a may be inclined with respect to the Z-axis direction and the Y-axis direction.

A plurality of first intermediate portions 52 may be provided in the first spacer 50. The plurality of first intermediate portions 52 are arranged along the Z-axis direction. The angle between the surface between the plurality of first intermediate portions 52 and the Z-axis direction may be changed in the plurality of first intermediate portions 52.

The first connecting portion 51 and the first intermediate portion 52 are a combination of a concave mirror and a plane mirror, a combination of a concave mirror and a concave mirror, a combination of a plane mirror and a plane mirror, and a combination of a concave mirror and a convex mirror. It may be provided in each of the above.

FIG. 10A and FIG. 10B are schematic views illustrating another resonator according to the first embodiment.
These drawings illustrate the first state ST1 and the second state ST2 in the resonator 116.

Also in the resonator 116, the first mirror 10 is a concave mirror, and the second mirror 20 is a plane mirror. In this example, the second spacer 60 is provided with a second connection portion 61 and a second intermediate portion 62. The second connection unit 61 is connected to the second mirror 20. The second intermediate part 62 is provided between the second connection part 61 and the first spacer 50.

In this example, the second connection portion 61 has a surface 61 a that faces the second intermediate portion 62. The second intermediate portion 62 has a surface 62 a that faces the second connection portion 61. The surface 62a is along the surface 61a. In this example, the surface 61a and the surface 62a are inclined with respect to the Z-axis direction.

As shown in FIGS. 10A and 10B, the relative position of the second spacer 60 with respect to the first spacer 50 changes between the first state ST1 and the second state ST2. At this time, in the second spacer 60, the relative position of the second intermediate portion 62 with respect to the second connection portion 61 changes. In the first state ST1 and the second state ST2, the second intermediate part 62 is in contact with the second connection part 61. In the first state ST1 and the second state ST2, the second intermediate portion 62 is in contact with the first spacer 50.

For example, the position of the second intermediate portion 62 in the second cross direction (for example, the X-axis direction) can be changed with respect to the position of the second connection portion 61 in the second cross direction. The second intersecting direction is a direction intersecting the first direction connecting the first mirror 10 in the first state ST1 and the second mirror 20 in the first state ST1.

In the resonator 116, the movement of the second spacer 60 uses the relative movement between the second intermediate part 62 and the second connection part 61 to move the position of the second mirror 20 to the position of the first mirror 10. The position can be changed greatly. Thereby, the resonator length can be changed greatly.

In this example, the first surface 50a is inclined with respect to the Z-axis direction. The surface 61a (and the surface 62a) is also inclined with respect to the Z-axis direction. The angle between the first surface 50a and the Z-axis direction is different from the angle between the surface 61a and the Z-axis direction. When the second spacer 60 is moved, the change rate of the resonator length with respect to the relative movement amount of the second connecting portion 61 with respect to the second intermediate portion 62 is relative to the first spacer 50 of the second intermediate portion 62. The rate of change of the resonator length with respect to the amount of movement is different. By changing the angles of these surfaces, it is possible to change the resonator length largely and to change it with high accuracy.

The inclination direction of the first surface 50a with respect to the Z-axis direction may be different from the inclination direction of the surface 61a with respect to the Z-axis direction. For example, the first surface 50a may be inclined with respect to the Z-axis direction and the X-axis direction, and the surface 61a may be inclined with respect to the Z-axis direction and the Y-axis direction.

A plurality of second intermediate portions 62 may be provided on the second spacer 60. The plurality of second intermediate portions 62 are arranged along the Z-axis direction. The angle between the surface between the plurality of second intermediate portions 62 and the Z-axis direction may be changed in the plurality of second intermediate portions 62.

The second connecting portion 61 and the second intermediate portion 62 are a combination of a concave mirror and a plane mirror, a combination of a concave mirror and a concave mirror, a combination of a plane mirror and a plane mirror, and a combination of a concave mirror and a convex mirror. It may be provided in each of the above.

In the resonator according to the embodiment, a plurality of spacers (first spacer 50, first connection portion 51 of first spacer 50, first intermediate portion 52 of first spacer 50, second spacer 60, second spacer 60 first 2 connection part 61, the 2nd intermediate part 62 of the 2nd spacer 60, etc.) may be provided. The number of the plurality of spacers may be two or three or more.

The first connection portion 51 may be regarded as the first spacer 50, and the first intermediate portion 52 may be regarded as the third spacer. The second connecting portion 61 may be regarded as the second spacer 60, and the second intermediate portion 62 may be regarded as the third spacer or the fourth spacer. For example, at least one of the first spacer 50 and the second spacer 60 may include two or more spacers.

For example, the resonator according to the present embodiment includes a first mirror 10, a second mirror 20, and a plurality of spacers. The plurality of spacers are provided between the first mirror 10 and the second mirror 20. The plurality of spacers are arranged in a direction connecting the first mirror 10 and the second mirror 20 (for example, the Z-axis direction). The plurality of spacers include, for example, a first spacer 50 in contact with the first mirror 10 (at least one of the outer edge portion 10r and the side surface of the first mirror 10), and the second mirror 20 (the outer edge portion 20r and the side surface of the second mirror 20). And a second spacer 60 in contact with at least one of the above.

The control unit 30 changes the length of the resonator formed by the first mirror 10 and the second mirror 20 by changing the position of at least one of the plurality of spacers. For example, in the first state ST1, the first mirror 10 and the second mirror 20 form a first resonator length L1. In the first state ST1, one of the plurality of spacers (for example, the first spacer 50) is in contact with the first mirror 10, and the other one of the plurality of spacers (for example, the second spacer 60) is the second. A plurality of closest spacers are in contact with the mirror 20 and in contact with each other.

The control unit 30 causes the first resonator 10 and the second mirror 20 to form the second resonator length L2 in the second state ST2. The second resonator length L2 is different from the first resonator length L1. In the second state ST2, one of the plurality of spacers (for example, the first spacer 50) is in contact with the first mirror 10, and the other one of the plurality of spacers (for example, the second spacer 60) is the second. A plurality of closest spacers are in contact with the mirror 20 and are in contact with each other. The second state ST2 is a state different from the first state ST1.
According to such a resonator, a resonator having a variable resonance frequency can be provided. That is, the resonance frequency can be changed while maintaining high frequency stability.

In an embodiment, the closest spacers (eg, first spacer 50 and second spacer 60, etc.) are mechanically formed by forming one or more contact states selected from point contact, line contact, and surface contact. It is preferable to form a stable state. The mechanically stable state referred to here is a state in which the relative position can be naturally maintained, and a support device or the like for maintaining the contact state is unnecessary. For example, in the example shown in FIGS. 3A and 3B, in the first state ST1 and the second state ST2, the first spacer 50 and the second spacer 60 are surfaces (first surface 50a and It is in contact with the second surface 60a). Thereby, the relative position of the 1st spacer 50 and the 2nd spacer 60 is stabilized. When contacting at a point, it is preferable to contact at three or more points. The relative position is stable. It is preferable that three or more points in contact with each other are separated from each other. The relative position is more stable.

For example, at the first and second points that are separated along the direction having the component in the X-axis direction and at the second point that is separated from the first and second points along the direction having the component in the Y-axis direction The first spacer 50 and the second spacer 60 are preferably in contact with each other. Thereby, a relative position becomes more stable.

For example, in the first state ST1, it is preferable that at least three points of the first spacer 50 are in contact with the second spacer 60. Also in the second state ST2, it is preferable that at least three points of the first spacer 50 are in contact with the second spacer 60.

In the embodiment, the first spacer 50 and the second spacer 60 preferably have a low coefficient of thermal expansion. The coefficient of thermal expansion at 20 ° C. of at least one of the first spacer 50 and the second spacer 60 is preferably 10 ⁻⁶ K ⁻¹ or less, for example. Thereby, the influence of the temperature change can be suppressed, and the resonator length, that is, the resonance frequency can be made more stable.

For the first spacer 50 and the second spacer 60, for example, it is preferable to use a low thermal expansion material having a low thermal expansion coefficient. As the low thermal expansion coefficient material, for example, a ceramic material having a thermal expansion coefficient of zero near room temperature may be used. For example, a material obtained by adding a small amount of titanium to silicon dioxide can be used. For example, a thermal expansion coefficient of about 0 ± 0.03 × 10 ⁻⁶ / K can be obtained at 5 ° C. to 35 ° C. An alloy having a low coefficient of thermal expansion near room temperature may be used. For example, an alloy containing iron, nickel and cobalt (for example, 32Ni-5Co—Fe) is used. In 32Ni-5Co-Fe, the composition ratio of nickel is about 32%, the composition ratio of cobalt is about 5%, and the composition ratio of iron is 63%. A thermal expansion coefficient of about 0.6 × 10 ⁻⁶ / K or less is obtained at 20 to 60 ° C.

In an embodiment, the resonator is stored in a container 80 as described with respect to FIG. The inside of the container 80 is depressurized. The container 80 is, for example, a decompression container (vacuum container). Thereby, the resonator is thermally shielded. Furthermore, the influence of atmospheric pressure is suppressed. The container 80 may be provided with a temperature adjusting element 82 such as a Peltier element so that the temperature in the container 80 is constant. Thereby, the ambient temperature of the resonator is kept constant.

FIG. 11A and FIG. 11B are schematic views illustrating another resonator according to the first embodiment.
FIG. 11A is a schematic perspective view. FIG. 11B is a plan view.
In FIG. 11A, the control unit 30 is omitted. As shown in FIG. 11A, the first spacer 50 and the second spacer 60 may be cylindrical.

As shown in FIG. 11 (b), first to third moving devices 31 to 33 are used as the control unit 30. When changing the state between the first state and the second state, the second spacer 60 is located between the two or more moving devices. After the state change (movement), the moving device is separated from the second spacer 60.

In the fields of high resolution spectroscopy and optical communication, extremely frequency stable light sources and highly accurate frequency measuring instruments are used. In order to obtain a frequency-stable light source and a highly accurate frequency measuring device, for example, a method of preparing an extremely frequency-stable frequency standard and locking the frequency of the light source is used. Frequency standards include atomic transitions, optical frequency combs, and reference resonators made of low thermal expansion materials. A reference resonator made of a low thermal expansion material having a coefficient of thermal expansion of zero near room temperature is relatively inexpensive and can provide high frequency stability.

The reference resonator has a resonance frequency unique to the resonator length. Therefore, it is not always possible to obtain a reference resonator having a standard frequency that is substantially the same as the required frequency. Therefore, a method using a frequency shifter, a method of changing the resonator length by moving the resonator mirror in the optical axis direction by a piezo element, and the like are adopted. In the case of the frequency shifter, if the shift amount is large, the device is expensive to obtain high accuracy, and the frequency is unstable due to the drive power source of the frequency shifter. On the other hand, when a piezo element is used, the frequency is unstable due to the piezo element and the driving device. In these methods, high frequency stability is impaired by changing the frequency. In a resonator, it is desirable to change the resonance frequency without impairing the frequency stability.

In this embodiment, for example, a plurality of spacers are provided between two facing mirrors, and the spacers are moved relatively. Thereby, a Fabry-Perot type optical resonator capable of shifting the resonator length is obtained. In the embodiment, the resonator length is determined only by the spacer length. Simple and stable structure. In the state before and after the change in the resonator length, the external force applied to the resonator does not change. A mechanism that impairs the adhesion between a plurality of spacers (divided spacers) is not used. A mechanism that keeps pushing (pulling) continuously after changing the resonator length is not used. That is, the frequency can be changed without using a mechanism that causes frequency instability.

According to this embodiment, the resonance frequency of the resonator can be changed without impairing the frequency stability.

(Second Embodiment)
In the present embodiment, one mirror moves on one spacer. In the present embodiment, the configuration and materials described in regard to the first embodiment can be applied to the mirror, the spacer, the fixing portion 81, and the container 80. Below, about 2nd Embodiment, a different part from 1st Embodiment is demonstrated. The description of the same parts as in the first embodiment will be omitted as appropriate.

FIGS. 12A and 12B are schematic views illustrating the resonator according to the second embodiment.
The resonator 120 according to the present embodiment includes a first mirror 10, a second mirror 20, a spacer 55 (first spacer), and a control unit 30. In this example, a fixing portion 81 is further provided. The resonator 120 can also be stored in the container 80 illustrated in FIG. 2 (for example, a decompression container).

The spacer 55 is provided between the first mirror 10 and the second mirror 20. At least a part of the spacer 55 may be provided between the first mirror 10 and the second mirror 20. The spacer 55 is connected to, for example, the outer edge portion 10r of the first mirror 10 and at least a part of the side surface. For example, the spatial position of the spacer 55 is fixed by the fixing portion 81. Thereby, for example, the spatial position of the first mirror 10 is defined.

In one state (for example, the first state ST1), a direction (first direction) connecting the first mirror 10 and the second mirror 20 is defined as a Z-axis direction.

As illustrated in FIG. 1B, the spacer 55 has a tubular shape (frame shape) with the Z-axis direction as an axis, for example. The spacer 55 may have a plurality of portions extending in the Z-axis direction. The spacer 55 may be connected to the first mirror 10 discontinuously by a plurality of portions.

The light reflected by the first mirror 10 and the second mirror 20 passes through the cavity formed inside the spacer 55. Also in this case, the first mirror 10 and the second mirror 20 form a Fabry-Perot type optical resonator. The light reflected by the first mirror surface 10 a and the second mirror surface 20 a does not pass through the spacer 55. In this example, each of the first mirror 10 and the second mirror 20 is a concave mirror.

The spacer 55 has a first surface 55 a that faces the first mirror 10 and a second surface 55 b that faces the second mirror 20.

The control unit 30 changes the position of the second mirror 20 to change the resonator length formed by the first mirror 10 and the second mirror 20. For example, the second mirror 20 moves on the spacer 55. For example, the second mirror 20 moves along the second surface 55b. This movement is performed by the control unit 30. Thereby, a plurality of states (first state ST1 and second state ST2) where the positions of the second mirror 20 are different from each other can be formed.

FIG. 12A and FIG. 12B illustrate the first state ST1 and the second state ST2, respectively.
In the first state ST1, the second mirror 20 is in contact with the spacer 55 (first spacer). In the first state ST1, the second mirror 20 is set at a first position relative to the first mirror 10. In the first state ST1, the first mirror 10 and the second mirror form a first resonator Rs1. In the first state ST1, the first mirror 10 and the second mirror 20 form a first resonator length L1.

Also in the second state ST2, the second mirror 20 is in contact with the spacer 55 (first spacer). In the second state ST2, the second mirror 20 is set to a second position relative to the first mirror 10. The second position is different from the first position. That is, the second mirror 20 is moved from the first position in the first state ST1. This movement is performed by the control unit 30. The movement of the second mirror 20 is a movement along the second surface 55 a of the spacer 55. The controller 30 causes the first resonator 10 and the second mirror 20 to form the second resonator Rs2 in the second state ST2. The controller 30 causes the first resonator 10 and the second mirror 20 to form the second resonator length L2 in the second state ST2. The second resonator length L2 is different from the first resonator length L1. In this example, the second resonator length L2 is shorter than the first resonator length L1. Thereby, the resonance frequency can be changed. Also according to this embodiment, a resonator having a variable resonance frequency can be provided.

In the present embodiment, in the first state ST1, the second mirror 20 is located at a first position relative to the first mirror 10. In the second state ST2, the second mirror 20 is located at a second position relative to the first mirror 10. The direction connecting the first position and the second position intersects the first direction (Z-axis direction) connecting the first mirror 10 in the first state ST1 and the second mirror 20 in the first state ST1. The direction connecting the first position and the second position intersects the second direction (Z-axis direction) connecting the first mirror 10 in the second state ST2 and the second mirror 20 in the second state ST2.

FIG. 13A and FIG. 13B are schematic views illustrating another resonator according to the second embodiment.
FIGS. 13A and 13B illustrate the first state ST 1 and the second state ST 2 in the resonator 121.

Also in the resonator 121, the first mirror 10, the second mirror 20, and the spacer 55 are provided. In these drawings, the control unit 30, the fixing unit 81, and the container 80 are omitted.

In this example, each of the first mirror 10 and the second mirror 20 is a concave mirror. The spacer 55 has a first surface 55 a that faces the first mirror 10 and a second surface 55 b that faces the second mirror 20. The second surface 55b is inclined with respect to the first surface 55a.

Also in this example, the second mirror 20 moves while the second mirror 20 is in contact with the spacer 55. The movement of the second mirror 20 is a movement along the second surface 55 a of the spacer 55. Also in this case, the first resonator length L1 in the first state ST1 is different from the second resonator length L2 in the second state ST2. A resonator having a variable resonance frequency can be provided.

Also in this case, the direction connecting the first position and the second position intersects the first direction (Z-axis direction) connecting the first mirror 10 and the second mirror 20 in the first state ST1. For example, the direction connecting the first position and the second position intersects the second direction (substantially the Z-axis direction) connecting the first mirror 10 and the second mirror 20 in the second state ST2.

FIG. 14A to FIG. 14D are schematic views illustrating another resonator according to the second embodiment.
FIGS. 14A to 14D illustrate one state (first state ST1) of the resonators 122 to 125 according to this embodiment.

In the resonator 122 and the resonator 123, the first mirror 10 is a plane mirror, and the second mirror 20 is a concave mirror. The first surface 55a and the second surface 55b are not parallel to each other. In the resonator 122 and the resonator 123, the direction of inclination of the first surface 55a with respect to the second surface 55b is different.

In the resonator 124 and the resonator 125, the first mirror 10 is a convex mirror, and the second mirror 20 is a concave mirror. In the resonator 124, the second surface 55b of the spacer 55 is perpendicular to the Z-axis direction. In the resonator 125, the second surface 55b of the spacer 55 is inclined with respect to the Z-axis direction.

Also in the resonators 122 to 125, the second mirror 20 moves while the second mirror 20 is in contact with the spacer 55. The movement of the second mirror 20 is a movement along the second surface 55 a of the spacer 55. Also in this case, the first resonator length L1 in the first state ST1 is different from the second resonator length L2 in the second state ST2. A resonator having a variable resonance frequency can be provided.

Also in the resonators 122 to 125, the direction connecting the first position and the second position intersects the first direction (Z-axis direction) connecting the first mirror 10 and the second mirror 20 in the first state ST1. For example, the direction connecting the first position and the second position intersects the second direction (Z-axis direction) connecting the first mirror 10 and the second mirror 20 in the second state ST2.

In this embodiment, a second spacer may be further provided in addition to the first spacer (spacer 55). The second spacer is provided, for example, between the first spacer (spacer 55) and the first mirror 10. The surface between the first spacer and the second spacer may be inclined with respect to the Z-axis direction, for example. For example, the amount of movement of the spacer can be increased. Set the tilt angle and tilt direction appropriately. As a result, it is possible to increase the amount of change in the resonator length with respect to the amount of movement of the spacer and to increase the accuracy of the amount of change in the resonator length.

Also in this embodiment, the resonator length is determined only by the spacer length. Simple and stable structure. In the state before and after the change in the resonator length, the external force applied to the resonator does not change. According to this embodiment, for example, the resonance frequency of the resonator can be changed without impairing the frequency stability.

FIG. 15A and FIG. 15B are schematic views illustrating the resonator according to the embodiment.
FIGS. 15A and 15B illustrate the first state ST1 and the second state ST2 in the resonator 131 of the first embodiment, respectively. In the resonator 131, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, the control unit 30, and the fixing unit 81 are provided.

A spacer member made of a low thermal expansion material having an outer shape with a height of 150 mm, a width of 50 mm, and a depth of 50 mm is divided into upper and lower parts to form the first spacer 50 and the second spacer 60. The first mirror 10 is connected to the bottom surface of the first spacer 50. The second mirror 20 is connected to the upper surface of the second spacer 60. The first mirror 10 is a concave mirror having a curvature radius of 1 m. The second mirror 20 is a plane mirror. The upper surface of the second spacer 60 is a plane.

The angle θ between the plane including the contact surfaces of the first spacer 50 and the second spacer 60 and the plane including the upper surface of the second spacer 60 is 0.022 degrees. This contact surface is, for example, perpendicular to the direction of gravity. The first spacer 50 is stably held by the fixing portion 81. The first spacer 50 is inclined at an angle of 0.022 degrees from a plane (ground) perpendicular to the direction of gravity. The second spacer 60 is placed on the first spacer 50 by gravity, for example.

For example, in the first state ST1, the side surface of the second spacer 60 is continuous with the side surface of the first spacer 50. The resonator length (first resonator length L1) at this time is about 150 mm.

The second spacer 60 is moved so as to change the resonator length. For example, a control unit 30 combining a micrometer head and a piezo actuator is used. For example, the control unit 30 pushes the second spacer 60 from a direction perpendicular to the direction of gravity.

The first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, the control unit 30 and the fixing unit 81 are stored in a decompressed container 80. The temperature adjustment element 82 adjusts the temperature in the container 80. The thermal expansion coefficients of the first spacer 50 and the second spacer 60 are substantially zero.

The central part of the first spacer 50 and the second spacer 60 is a cavity. A resonator mode is formed at the center of the cavity. When light is incident on the resonator 131, this light passes through the mirror and the cavity. No influence such as scattering by the spacer occurs.

As shown in FIG. 15B, the position of the second spacer 60 is changed by the operation of the control unit 30 in the second state ST2. Thereby, the positions of the second spacer 60 and the second mirror 20 connected to the second spacer 60 are changed. For example, the movement distance Δd of the second spacer 60 is 1.5 mm. The direction of movement is perpendicular to gravity. During the movement, the control unit 30 contacts the second spacer 60. After the movement, the control unit 30 is separated from the second spacer 60.

The second resonator length L2 (that is, L1 + ΔL) in the second state ST2 is expressed as follows.

L1 + ΔL = 150−1.5 × sin (0.022 °) = 149.994 (mm)

It is assumed that one resonance frequency ν of the resonator in the first state ST1 is 247 THz (terahertz). At this time, from the first equation, the change in the resonance frequency in the second state ST2 from the first state ST1, that is, the frequency shift amount Δν is about 1 GHz (gigahertz).

FIG. 16A and FIG. 16B are schematic views illustrating the resonator according to the embodiment.
FIG. 16A and FIG. 16B illustrate the first state ST1 and the second state ST2 in the resonator 132 of the second embodiment, respectively. Also in the resonator 132, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, the control unit 30, and the fixing unit 81 are provided. Hereinafter, the difference between the resonator 132 and the resonator 131 will be described.

In the resonator 132, a concave mirror having a curvature radius of 1 m is used for the first mirror 10. A concave mirror with a radius of curvature of 1 m is also used for the second mirror 20. Two concave surfaces oppose each other. A distance d1 in the Z-axis direction between the first mirror 10 and the second mirror 20 is 150 mm. A distance d2 in the Z-axis direction between the first center 10c of the first mirror 10 and the second center 20c of the second mirror 20 is 1850 mm.

The direction connecting the first mirror 10 and the second mirror 20 in the first state ST1 is, for example, parallel to gravity. The contact surface between the first spacer 50 and the second spacer 60 is perpendicular to gravity.
The first resonator length L1 in the first state ST1 is 150 mm.

In the second state ST2, the control unit 30 moves the second spacer 60. The direction of movement is perpendicular to gravity. The movement distance Δd of the second spacer 60 is 5.23 mm. After the movement, the control unit 30 is separated from the second spacer 60.

The second resonator length L2 (that is, L1 + ΔL) in the second state ST2 is expressed as follows.

L1 + ΔL = 150 / cos {tan ⁻¹ (5.23 / 1850)} = 150.0006 (mm)

Assume that one resonance frequency ν of the resonator in the first state ST1 is 247 THz. At this time, from the first equation, the frequency shift amount Δν generated in the second state ST2 is about −1 GHz.

FIG. 17A and FIG. 17B are schematic views illustrating the resonator according to the embodiment.
FIGS. 17A and 17B illustrate the first state ST1 and the second state ST2 in the resonator 133 according to the third embodiment, respectively. Also in the resonator 133, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, the control unit 30, and the fixing unit 81 are provided. Hereinafter, the difference between the resonator 133 and the resonator 131 will be described.

In the resonator 133, planar mirrors are used for the first mirror 10 and the second mirror 20, respectively. In the first state ST1, the distance between the first mirror 10 and the second mirror 20 is 150 mm. The angle θ between the plane including the contact surfaces of the first spacer 50 and the second spacer 60 and the plane including the upper surface of the second spacer 60 is 0.022 degrees.

As shown in FIG. 17B, the second spacer 60 is moved by the control unit 30 in the second state ST2. The direction of movement is perpendicular to gravity. The moving distance of the second spacer 60 is 1.5 mm. After the movement, the control unit 30 is separated from the second spacer 60.

The second resonator length L2 (that is, L1 + ΔL) in the second state ST2 is expressed as follows.

L1 + ΔL = 150−1.5 × sin (0.022 °) = 149.994 (mm)

Assume that one resonance frequency ν of the resonator in the first state ST1 is 247 THz. At this time, from the first equation, the frequency shift amount Δν that occurs in the second state ST2 is about 1 GHz.

18A and 18B are schematic views illustrating the resonator according to the embodiment.
FIGS. 18A and 18B illustrate the first state ST1 and the second state ST2 in the resonator 134 of the fourth embodiment, respectively. Also in the resonator 134, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, the control unit 30, and the fixing unit 81 are provided. Hereinafter, the difference between the resonator 134 and the resonator 131 will be described.

In the resonator 134, a convex mirror having a curvature radius of 1 m is used for the first mirror 10. The second mirror 20 is a concave mirror having a curvature radius of 1 m. The convex surface of the first mirror 10 and the concave surface of the second mirror 20 face each other. A distance d1 in the Z-axis direction between the first mirror 10 and the second mirror 20 is 150 mm. The distance d2 in the Z-axis direction between the first center 10c of the first mirror 10 and the second center 20c of the second mirror 20 is 1150 mm. The mutual contact surfaces (first surface 50 a and second surface 60 a) of the first spacer 50 and the second spacer 60 are perpendicular to the direction connecting the first mirror 10 and the second mirror 20. This contact surface is perpendicular to the direction of gravity.

The first resonator length L1 in the first state ST1 is 150 mm.

As shown in FIG. 18B, the second spacer 60 is moved by the control unit 30 in the second state ST2. The direction of movement is perpendicular to gravity. The movement distance Δd of the second spacer 60 is 0.42 mm. After the movement, the control unit 30 is separated from the second spacer 60.

The second resonator length L2 (that is, L1 + ΔL) in the second state ST2 is expressed as follows.

L1 + ΔL = {150 ² +0.42 ² } ^1/2 = 150.0006 (mm)

Assume that one resonance frequency ν of the resonator in the first state ST1 is 247 THz. At this time, from the first equation, the frequency shift amount Δν generated in the second state ST2 is about −1 GHz.

In the above-described resonators 131 to 134, a new external force that causes frequency instability before and after the resonator length change is not applied. For this reason, the resonance frequency can be greatly shifted without impairing high frequency stability.

FIG. 19 is a schematic view illustrating the resonator according to the embodiment.
FIG. 19 illustrates the first state ST1 in the resonator 135 of the fifth embodiment. Also in the resonator 135, the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30 are provided. In the resonator 135, a spacer member 25 is further provided.

In the resonator 135, a concave mirror with a radius of curvature of 1 m is used for the first mirror 10, and a concave mirror with a radius of curvature of 1 m is also used for the second mirror 20. Two concave surfaces oppose each other. Hereinafter, the difference between the resonator 135 and the resonator 132 will be described.

In the resonator 135, the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer 60 are provided on the spacer member 25. The spacer member 25 is made of the same material as the first spacer 50 and the second spacer 60. A direction (Z-axis direction) connecting the first mirror 10 and the second mirror 20 is, for example, perpendicular to gravity. That is, the resonator 135 is a horizontally placed resonator.

The first resonator length L1 in the first state ST1 is 150 mm.

The control unit 30 moves the second spacer 60, for example, along the Y-axis direction. The moving distance of the second spacer 60 is, for example, 5.23 mm. In the first state ST1 and the second state ST2, the second spacer 60 is in contact with the first spacer 50. After the movement, the control unit 30 is separated from the second spacer 60.

In a horizontally mounted resonator, if a material having a coefficient of thermal expansion different from that of the resonator is disposed under the resonator (two spacers), for example, two spacers are caused by the thermal expansion of the material disposed below. In some cases, the positional relationship may change due to separation. Thereby, the stability of the frequency may be deteriorated. By providing a substance (spacer member 25) having the same thermal expansion coefficient under the resonator (two spacers), high frequency stability can be maintained before and after the resonator length shift.

FIG. 20A and FIG. 20B are schematic views illustrating the resonator according to the embodiment.
20A and 20B illustrate the first state ST1 and the second state ST2 in the resonator 146 of the sixth embodiment, respectively. In the resonator 146, the first mirror 10, the second mirror 20, and the spacer 55 are provided. In these drawings, the control unit 30, the container 80, the temperature adjusting element 82, and the like are omitted.

The width of the bottom surface of the spacer 55 is 70 mm, and the depth of the bottom surface is 70 mm. The spacer 55 is made of a low thermal expansion material. The angle θ between the plane including the upper surface of the spacer 55 and the plane including the bottom surface is 0.022 degrees. The upper surface of the spacer 55 is, for example, perpendicular to gravity. The spacer 55 is stably held by the fixing portion 81.

The first mirror 10 is connected to the bottom surface of the spacer 55. The second mirror 20 is disposed on the upper surface of the spacer 55. The first mirror 10 is a plane mirror. The second mirror 20 is a concave mirror. The radius of curvature of the concave mirror is 0.2 m. The second mirror 20 is on the spacer 55 by gravity.

20B, in the second state ST2, the position of the second mirror 20 is changed by the operation of the control unit 30. In the first state ST1 and the second state ST2, the second mirror 20 is in contact with the spacer 55. The movement distance Δd of the second mirror 20 is 1.5 mm. The direction of movement is perpendicular to gravity. During the movement, the control unit 30 contacts the second spacer 60. After the movement, the control unit 30 is separated from the second spacer 60.

The second resonator length L2 (that is, L1 + ΔL) in the second state ST2 is expressed as follows.

L1 + ΔL = 150−1.5 × sin (0.022 °) = 149.994 (mm)

Assume that one resonance frequency ν of the resonator in the first state ST1 is 247 THz. At this time, from the first equation, the change in the resonance frequency from the first state ST1 in the second state ST2, that is, the frequency shift amount Δν is about 1 GHz.

FIG. 21A and FIG. 21B are schematic views illustrating the resonator according to the embodiment.
FIGS. 21A and 21B illustrate the first state ST1 and the second state ST2 in the resonator 147 of the seventh embodiment, respectively. Also in the resonator 147, the first mirror 10, the second mirror 20, and the spacer 55 are provided. In these drawings, the control unit 30, the fixing unit 81, the container 80, the temperature adjustment element 82, and the like are omitted.

The upper surface of the spacer 55 is parallel to the bottom surface of the spacer 55. The first mirror 10 is connected to the bottom surface of the spacer 55. The second mirror 20 is disposed on the upper surface of the spacer 55. The first mirror 10 is a concave mirror having a radius of curvature of 1 m. A concave mirror having a radius of curvature of 1 m is used for the second mirror 20. The second mirror 20 is on the spacer 55 by gravity.

A distance d1 in the Z-axis direction between the first mirror 10 and the second mirror 20 is 150 mm. A distance d2 in the Z-axis direction between the first center 10c of the first mirror 10 and the second center 20c of the second mirror 20 is 1850 mm.
The first resonator length L1 in the first state ST1 is 150 mm.

21B, the second spacer 60 is moved by the control unit 30 in the second state ST2. The direction of movement is perpendicular to gravity. The moving distance of the second spacer 60 is 5.23 mm. After the movement, the control unit 30 is separated from the second spacer 60.

In the above-described

resonators

146 and 147, new external force that causes frequency instability before and after the resonator length change is not applied. For this reason, the resonance frequency can be greatly shifted without impairing high frequency stability.

(Third embodiment)
The present embodiment relates to a light source device. The light source device according to the embodiment includes a resonator and a light source. FIG. 22 is a schematic view illustrating the light source device according to the third embodiment.
As illustrated in FIG. 22, the light source device 210 according to the embodiment includes a resonator 131 and a light source 71. For example, a laser light source is used as the light source 71. The frequency of the light source 71 is locked to the resonator 131. In this example, a resonator 131 is used as the resonator. In the present embodiment, any resonator according to the first and second embodiments and modifications thereof can be used.

In this example, a frequency control device 73 is further provided. The light source 71 emits laser light. A part of the laser light is incident on the second mirror 20. The frequency control device 73 controls the light source 71 so that the center frequency of the light source 71 matches one of the resonance frequencies of the resonator mode of the resonator 131. For example, the frequency control device 73 detects the laser light reflected by the second mirror 20 and adjusts the center frequency of the light source 71 based on the detection result.

For example, a low thermal expansion material is used for the spacer, and the temperature of the container 80 is controlled to keep the spacer at a temperature at which the thermal expansion coefficient is lowered. Thereby, the resonance frequency of the resonator mode is stable. The light source 71 whose frequency is locked in the resonator mode can obtain very high frequency stability.

In this example, a beam splitter 72 is further provided. The beam splitter 72 is provided between the light source 71 and the second mirror 20 on the optical path of the light source 71. The beam splitter 72 takes out the laser light generated by the light source 71 as output light of the light source device 210.

The resonance frequency of the resonator mode in the resonator 131 is adjusted by moving the second spacer 60. By adjusting the resonance frequency of the resonator mode by moving the second spacer 60, the frequency of the output light of the light source device 210 can be adjusted.

The light source device according to the present embodiment uses the resonator according to the embodiment, so that the frequency of the output light is variable and high frequency stability can be realized.

FIG. 23 is a schematic view illustrating another light source device according to the third embodiment.
As shown in FIG. 23, in another light source device 211 according to the present embodiment, a frequency shifter 74 is further provided. Other than this, the light source device 210 is the same as the light source device 210, and the description thereof is omitted.

In the light source device 211, the frequency of the light source 71 is shifted by the frequency shifter 74. For example, the resonator length is shifted by the control unit 30 to roughly shift the resonance frequency. The shift amount of the resonance frequency is about 1 GHz. Then, the laser frequency is finely adjusted using the frequency shifter 74 with a small shift amount. An inexpensive device can be used for the control unit 30, and an inexpensive device can be used for the frequency shifter 74.

For example, when the frequency shifter 74 is not used, the frequency stability is high. By using the frequency shifter 74, the frequency stability may be lowered. However, by using the frequency shifter 74 for fine adjustment of the frequency shift, an inexpensive device with low shift accuracy can be used as the control unit 30. Therefore, a low-cost light source device can be obtained with an inexpensive configuration combining the inexpensive control unit 30 and the frequency shifter 74 with low movement accuracy.

By using an acousto-optic modulator or an electro-optic modulator as the frequency shifter 74, the frequency can be swept continuously repeatedly.

In the light source device according to the present embodiment, the light emitted from the light source 71 is, for example, at least one of a first frequency corresponding to the first resonator length L1 and a second frequency corresponding to the second resonator length L2. Have

(Fourth embodiment)
The present embodiment relates to a frequency filter. The frequency filter according to the embodiment includes a resonator.
FIG. 24 is a schematic view illustrating a frequency filter according to the fourth embodiment.
As shown in FIG. 24, the frequency filter 310 according to the present embodiment includes a resonator 131. In this example, the resonator 131 is used as the resonator, but the resonators according to the first and second embodiments and modifications thereof can be used.

In this example, a light source 75 is provided. Light emitted from the light source 75 enters the resonator 131. For example, the light enters the second mirror 20 and exits from the first mirror 10.

The light source 75 is, for example, a two-color light source. The light source 75 emits, for example, first light and second light 2. The spectral width of each of the first light and the second light is about 1 kHz. The center frequencies of the first light and the second light are different from each other. Each of the first light and the second light is laser light. The frequency of the first light is, for example, 247 THz. The frequency of the second light is, for example, 247 THz + 0.5 GHz. It is assumed that the spectrum width of the resonance frequency of the resonator 131 is 5 KHz. In the present embodiment, the light emitted from the light source 75 has, for example, at least one of a first frequency corresponding to the first resonator length L1 and a second frequency corresponding to the second resonator length L2.

In the first state ST1 before moving the second spacer 60, the laser light from the light source 75 enters the second mirror 20. The resonator 110 functions as an optical selection filter. In this light selection filter, the second light is reflected and the first light is transmitted.

After moving the second spacer 60, the second state ST2 is formed. The movement distance is, for example, 0.75 mm. At this time, the resonator 131 functions as a light selection filter that reflects the first light and transmits the second light.

For example, a low thermal expansion material is used for the spacer, and the temperature of the container 80 is controlled to keep the spacer at a temperature at which the thermal expansion coefficient is lowered. Thereby, the resonance frequency of the resonator mode is stable. The resonator 131 can be used as a frequency filter having very high frequency stability.

According to this embodiment, the resonator can be used as a frequency filter having a variable frequency and high frequency stability of the transmission spectrum.

In the first to fourth embodiments, the Z-axis direction connects, for example, the center of the first mirror 10 and the center of the second mirror 20 in one state (for example, the first state ST1). Corresponds to the direction.

In the Fabry-Perot type optical resonator, when a concave mirror and a plane mirror are provided, for example, as illustrated in FIGS. 3A and 3B, along a direction inclined with respect to the plane of the plane mirror. The second spacer 60 is moved relative to the first spacer 50. As a result, the resonator length changes.

The

resonators

110, 111, 112a to 112c, 113, 114a, 114b, 115, 116, and 131 to 135 include the first mirror 10, the second mirror 20, the first spacer 50, and the second spacer. 60. In these resonators, in the first state ST1, the second spacer 60 (for example, the second surface 60a) is in contact with at least a part of the first spacer 50 (the first surface 50a). In these resonators, in the second state ST2, the second spacer 60 (for example, the second surface 60a) is in contact with at least a part of the first spacer 50 (first surface 50a). In a state (for example, moving) between the first state ST1 and the second state ST2, the second spacer 60 (for example, the second surface 60a) is separated from the first spacer 50 (the first surface 50a). May be. In a state (for example, moving) between the first state ST1 and the second state ST2, the control unit 30 is in contact with the spacer (for example, the second spacer 60).

In the

resonators

110, 111, 112 a to 112 c, 113, 114 a, 114 b, 115, 116, and 131 to 135, the first spacer 50 has a spacer portion and a space between the spacer portion and the second spacer 60. And a layer (for example, a layer such as a lubricating oil) provided on the surface. The surface of this layer may form the first surface 50a. The second spacer 60 may include a spacer portion and a layer (for example, a layer of lubricating oil) provided between the spacer portion and the first spacer 50. The surface of this layer may form the second surface 60a.

The resonators 120 to 125, 146, and 147 include the first mirror 10, the second mirror 20, and the spacer 55 (first spacer). These resonators may further include a control unit 30. At least a part of the spacer 55 is provided between the first mirror 10 and the second mirror 20. The spacer 55 is in contact with the first mirror 10. For example, the spacer 55 is coupled to the first mirror 10. In the first state ST1 where the spacer 55 and the second mirror 20 are in contact with each other, the first resonator length L1 formed by the first mirror 10 and the second mirror 20 is such that the spacer 55 and the second mirror 20 are The second resonator length L2 formed by the first mirror 10 and the second mirror 20 in the second state ST2 in contact with the second state ST2 is different. The second state ST2 is different from the first state ST1. The first relative position of the second mirror 20 with respect to the first mirror 10 in the first state ST1 is different from the second relative position of the second mirror 20 with respect to the first mirror 10 in the second state ST2. The direction connecting the first position and the second position intersects the direction connecting the center of the first mirror 10 in the first state ST1 and the center of the second mirror 20 in the first state ST1.

In the resonators 120 to 125, 146, and 147, in the first state ST1, the spacer 55 (for example, the second surface 55b) is in contact with at least a part of the second mirror 20 (second mirror surface 20a). . In these resonators, in the second state ST2, the spacer 55 (for example, the second surface 55b) is in contact with at least a part of the second mirror 20 (second mirror surface 20a). In a state (for example, moving) between the first state ST1 and the second state ST2, the spacer 55 (for example, the second surface 55b) is separated from the second mirror 20 (second mirror surface 20a). Also good. In a state (for example, during movement) between the first state ST1 and the second state ST2, the control unit 30 is in contact with the second mirror 20.

(Fifth embodiment)
FIG. 25A to FIG. 25F are schematic views illustrating the resonator according to the fifth embodiment.
FIG. 25A and FIG. 25B are perspective views. 25 (c) and 25 (d) are plan views from the direction of the arrow Ar1 shown in FIG. 25 (a). 25 (e) and 25 (f) are plan views from the direction of the arrow Ar2 shown in FIG. 25 (a). FIG. 25A, FIG. 25C, and FIG. 25E correspond to the first state ST1. FIG. 25B, FIG. 25D, and FIG. 25F correspond to the second state ST2.

As shown in FIG. 25A, the resonator 151 according to this embodiment includes the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30. Including. The “mirror” includes a case where one mirror element is included and a case where a plurality of mirror elements are included. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11 and the second mirror element 12). The second mirror 20 includes a plurality of mirror elements 20e (for example, a third mirror element 23 and a fourth mirror element 24). Other than this, for example, it is the same as the resonator 110. In the resonator 151, a fixing part 81, a container 80, and a temperature adjustment element 82 may be provided. In these drawings, the fixing portion 81, the container 80, and the temperature adjustment element 82 are omitted.

In the first state ST1 shown in FIG. 25A, one point of the first mirror 10 (for example, one point of the first mirror element 11) and one point of the second mirror 20 (for example, the third mirror element). 23) is defined as a Z-axis direction. For example, the Z-axis direction is a direction connecting the center of the first mirror 10 and the center of the second mirror 20 in one state (for example, the first state ST1). In this example, the center of the first mirror 10 is the midpoint between the first mirror element 11 and the second mirror element 12. The center of the second mirror 20 is the midpoint between the third mirror element 23 and the fourth mirror element 24.

The second mirror element 12 is aligned with the first mirror element 11 in one direction that intersects the Z-axis direction (in this example, the X-axis direction). The second mirror element 12 is separated from the first mirror element 11 in one direction that intersects the Z-axis direction (in this example, the X-axis direction).

The fourth mirror element 24 is aligned with the third mirror element 23 in one direction that intersects the Z-axis direction (in this example, the X-axis direction). The fourth mirror element 24 is separated from the third mirror element 23 in one direction that intersects the Z-axis direction (in this example, the X-axis direction).

In this example, the first mirror element 11, the second mirror element 12, the third mirror element 23, and the fourth mirror element are provided in the XZ plane.

In this example, these mirror elements are plane mirrors. In the embodiment, the third mirror element 23 and the fourth mirror element 24 may be concave mirrors. In this case, the curvature of the fourth mirror element 24 may be set substantially the same as the curvature of the third mirror element 23.

In the first state ST1 shown in FIG. 25A, the first spacer 50 is in contact with the first mirror 10 and the second spacer 60. The second spacer 60 is in contact with the second mirror 20 and the first spacer 50.

In the second state ST2 shown in FIG. 25B, the first spacer 50 is in contact with the first mirror 10 and the second spacer 60. The second spacer 60 is in contact with the second mirror 20 and the first spacer 50. The relative position (second position) of the second spacer 60 to the first spacer 50 in the second state ST2 is the relative position (first position) of the second spacer 60 to the first spacer 50 in the first state ST1. Is different.

In this example, the first surface 50a of the first spacer 50 is inclined with respect to the Z-axis direction. The second surface 60a of the second spacer 60 is along the first surface 50a. In the second state ST2, a plane including the first mirror element 11 and the second mirror element 12 (a plane parallel to the XZ plane) is a plane including the third mirror element 23 and the fourth mirror element 24 ( And a plane parallel to the XZ plane).

For example, a cavity is provided in the first spacer 50 and in the second spacer 60. A cavity is provided in the central portion of the first spacer 50 and the central portion of the second spacer 60. Light can pass through these cavities. When light enters the resonator 151, the light passes through the cavity. For this reason, for example, the influence such as light scattering by the spacer material does not substantially occur.

As shown in FIG. 25C, in the first state ST1, for example, the light Li is incident on the first mirror element 11. For example, the reflectance of the first mirror element 11 is 99%, and the transmittance of the first mirror element 11 is 1%. A part of the light Li, LL, enters from the first mirror element 11 toward the second mirror element 12 and is reflected by the second mirror element 12. The traveling direction of the light LL changes due to reflection. The angle of change is 90 degrees. The light LL reflected by the second mirror element 12 enters the fourth mirror element 24, and the light LL is reflected by the fourth mirror element 24. The traveling direction of the light LL changes due to reflection. The angle of change is 90 degrees. The light LL reflected by the fourth mirror element 24 enters the third mirror element 23, and the light LL is reflected by the third mirror element 23. The traveling direction of the light LL changes due to reflection. The angle of change is 90 degrees. The light LL reflected by the third mirror element 23 enters the first mirror element 11. A part of the light LL incident on the first mirror element 11 passes through the first mirror element 11 and is emitted to the outside. In the first state ST1, the first resonator Rs1 is formed. In the first state ST1, the first resonator length L1 is formed.

As shown in FIG. 25 (d), in the second state ST2, for example, a part of the light LL is incident on the first mirror element 11, reflected by the second mirror element 12, and the fourth mirror element. 24, reflected by the third mirror element 23, and incident on the first mirror element 11. A part of the light LL incident on the first mirror element 11 passes through the first mirror element 11 and is emitted to the outside. In the second state ST2, the second resonator Rs2 is formed. In the second state ST2, the second resonator length L2 is formed.

The relative position of the second spacer 60 with respect to the first spacer 50 in the second state ST2 is different from the relative position of the second spacer 60 with respect to the first spacer 50 in the first state ST1. Accordingly, the second resonator length L2 is different from the first resonator length L1.

In the resonator 151, the first mirror 10 and the second mirror 20 form, for example, a ring type optical resonator. The first mirror 10 and the second mirror 20 form, for example, a loop type optical resonator. The first mirror 10 and the second mirror 20 form, for example, a circulating optical resonator. In these resonators, at least one of the first mirror 10 and the second mirror 20 includes a plurality of mirror elements. That is, in the resonator, the number of mirror elements may be three or more.

For example, in the case of a Fabry-Perot resonator, two mirrors (mirror elements) are provided. The number of mirror elements is two. For example, in a Fabry-Perot resonator, the distance between the first mirror 10 and the second mirror 20 corresponds to the resonator length.

On the other hand, in a ring type optical resonator (for example, a loop type optical resonator or a circulation type optical resonator), the number of mirror elements is three or more. In the resonator 151, the number of mirror elements is four. In the resonator 151, the light LL is reflected by a plurality of mirror elements and returns to the mirror element (first mirror element 11) on which the light LL is incident. The light LL that has passed through the first mirror element 11 (a part of the light Li that has entered the first mirror element 11) is another mirror element (the second mirror element 12, the fourth mirror element 24, and the third mirror element 23). The length of the path of the light LL until it enters the first mirror element 11 via the line corresponds to the resonator length.

In the resonator 151, the resonator length is the distance between the first mirror element 11 and the second mirror element 12 (distance on the optical path) and the distance between the second mirror element 12 and the fourth mirror element 24. The distance (distance on the optical path), the distance between the fourth mirror element 24 and the third mirror element 23 (distance on the optical path), and the distance between the third mirror element 23 and the first mirror element 11 ( The distance on the optical path).

As shown in FIG. 25C, FIG. 25D, FIG. 25E, and FIG. 25F, the distance between the second mirror element 12 and the fourth mirror element 24 in the second state ST2 is The distance between the second mirror element 12 and the fourth mirror element 24 in the first state ST1 is different. The distance between the third mirror element 23 and the first mirror element 11 in the second state ST2 is different from the distance between the third mirror element 23 and the first mirror element 11 in the first state ST1.

In the resonator 151, an angle between the first surface 50a of the first spacer 50 and the XY plane (a plane perpendicular to the Z-axis direction) is, for example, 0.022 degrees. The angle between the second surface 60a of the second spacer 60 and the XY plane is, for example, 0.022 degrees. The first surface 50a and the second surface 60a are inclined with respect to the XY plane.

For example, the first surface 50a and the second surface 60a are set perpendicular to the direction of gravity. This setting is performed by, for example, the fixing unit 81 (not shown in FIGS. 25A to 25F).

The second spacer 60 is disposed on the first spacer 50, for example. The relative position of the second spacer 60 along the direction of gravity with respect to the first spacer 50 is fixed.

For example, in the first state ST1, one side surface of the second spacer 60 is continuous with one side surface of the first spacer 50. The first resonator length L1 in the first state ST1 is about 150 mm.

The second state ST2 is formed by the control unit 30. For example, the control unit 30 changes the relative position of the second spacer 60 (or at least one of the second spacer 60 and the second mirror 20) with respect to the first spacer 50. The change of the position is performed in a plane along the first surface 50a and the second surface 60a, for example. The position is changed, for example, in a plane perpendicular to the direction of gravity. The direction in which the position is changed intersects, for example, the direction connecting the first mirror element 11 and the third mirror element 23. The direction in which the position is changed is, for example, the direction connecting the second mirror element 12 and the fourth mirror element 24, the direction connecting the first mirror element 11 and the fourth mirror element, and the second mirror element 12 It further intersects with the direction connecting the third mirror element 23. The position is changed in, for example, a plurality of directions (for example, four directions) in a plane perpendicular to the direction of gravity. In the second state ST2, one side surface of the second spacer 60 is discontinuous with one side surface of the first spacer 50.

For example, the relative position between the first spacer 60 of the second spacer 60 and the first state ST1 shown in FIG. 25E and the second state ST2 shown in FIG. Be changed. The distance of movement accompanying the change of the relative position is, for example, 0.75 mm. The direction of movement is perpendicular to gravity. During the movement, the control unit 30 is in contact with the second spacer 60 (or at least one of the second spacer 60 and the second mirror 20). After the movement, the control unit 30 is separated from the second spacer 60 (or at least one of the second spacer 60 and the second mirror 20). Thereby, the second state ST2 is formed.

Due to the movement, the distance between the third mirror element 23 and the first mirror element 11 changes, and the distance between the second mirror element 12 and the fourth mirror element 24 changes. The distance (second state distance) between the third mirror element 23 and the first mirror element 11 in the second state ST2 is the distance between the third mirror element 23 and the first mirror element 11 in the first state ST1. Shorter than (first state distance). The difference between the second state distance and the first state distance is, for example, 0.75 × sin (0.022 degrees) mm, which is about 0.0003 mm. The distance (second state distance) between the second mirror element 12 and the fourth mirror element 24 in the second state ST2 is the distance between the second mirror element 12 and the fourth mirror element 24 in the first state ST1. Shorter than (first state distance). The difference between the second state distance and the first state distance is, for example, 0.75 × sin (0.022 degrees) mm, which is about 0.0003 mm.

Accordingly, the second resonator length L2 in the second state ST2 is as follows.
L2 = L1 + ΔL = 150 + (− 0.0003−0.0003) = 149.994 (mm).

Suppose that one of resonance frequencies ν (first resonance frequency) corresponding to the first resonator length L1 (resonator length before the resonator length is changed) is 247 THz. The resonance frequency (second resonance frequency) corresponding to the second resonator length L2 (resonator length after the resonator length has changed) is different from the first resonance frequency. The difference (frequency shift amount Δν) between the second resonance frequency and the first resonance frequency is about 1 GHz. In the embodiment, the resonance frequency can be shifted greatly.

In the embodiment, before and after the change of the resonator length, an external force that causes frequency instability is suppressed from being applied to the resonator. High stability is obtained at the resonance frequency.

In the resonator 151, the position in the X-axis direction of the first mirror element 11 in the second state ST2 is the same as the position in the X-axis direction of the first mirror element 11 in the first state ST1. The position in the X-axis direction of the second mirror element 12 in the second state ST2 is the same as the position in the X-axis direction of the second mirror element 12 in the first state ST1. The position in the X-axis direction of the third mirror element 23 in the second state ST2 is the same as the position in the X-axis direction of the third mirror element 23 in the first state ST1. The position in the X-axis direction of the fourth mirror element 24 in the second state ST2 is the same as the position in the X-axis direction of the fourth mirror element 24 in the first state ST1.

In the embodiment, the number of the plurality of mirror elements 10e provided in the first mirror 10 may be three or more. The number of the plurality of mirror elements 20e provided in the second mirror 20 may be three or more.

FIGS. 26A to 26D are schematic views illustrating another resonator according to the fifth embodiment.
FIG. 26A and FIG. 26C correspond to the first state ST1. FIG. 26B and FIG. 26D correspond to the second state ST2.

As shown in FIG. 26A, another resonator 152 according to the present embodiment includes a first mirror 10, a second mirror 20, a first spacer 50, a second spacer 60, a control unit 30, and the like. ,including. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11 and the second mirror element 12). The second mirror 20 includes a third mirror element 23. Other than this, for example, it is the same as the resonator 110. In the resonator 152, a fixing part 81, a container 80, and a temperature adjustment element 82 may be provided. In these drawings, the fixing portion 81, the container 80, and the temperature adjustment element 82 are omitted.

In the resonator 152, for example, the Z-axis direction is, for example, a direction connecting the center of the first mirror 10 and the center of the second mirror 20 in one state (for example, the first state ST1). In this example, the center of the first mirror 10 is the midpoint between the first mirror element 11 and the second mirror element 12. The direction connecting this midpoint and the center of the second mirror 20 (third mirror element 23) is the Z-axis direction.

In the resonator 152, the first mirror element 11, the second mirror element 12, and the third mirror element 23 are plane mirrors. Each of the plane including the first mirror element 11, the plane including the second mirror element 12, and the plane including the third mirror element 23 is parallel to the Y-axis direction.

As shown in FIG. 26A, light Li is incident on the first mirror element 11. For example, the reflectance of the first mirror element 11 is 99%, and the transmittance of the first mirror element 11 is 1%. A part of the light Li, LL, passes through the first mirror element 11 and then enters the second mirror element 12. The light LL is reflected by the second mirror element 12. The incident angle at the second mirror element 12 is 35 degrees and the reflection angle is 35 degrees. The incident angle is an angle between the direction perpendicular to the surface of the second mirror element 12 and the light LL incident on the second mirror element 12. The reflection angle is an angle between a direction perpendicular to the surface of the second mirror element 12 and the light LL reflected by the second mirror element 12. The light LL reflected by the second mirror element 12 travels toward the second mirror 20 (third mirror element 23). The light LL is reflected by the second mirror 20. The light LL reflected by the second mirror 20 enters the first mirror element 11. A part of the light LL incident on the first mirror element 11 is emitted to the outside.

In the first state ST1, the first resonator length L1 is determined by the distance between the first mirror element 11 and the second mirror element 12 (distance on the optical path), the second mirror element 12 and the second mirror 20 (first 3 (the distance on the optical path) and the distance between the second mirror 20 (the third mirror element 23) and the first mirror element 11 (the distance on the optical path). It is.

As shown in FIGS. 26A and 26C, the first surface 50a of the first spacer 50 is inclined with respect to the XY plane (a plane perpendicular to the Z-axis direction). The second surface 60a of the second spacer 60 is inclined with respect to the XY plane. The relative position of the second spacer 60 with respect to the first spacer 50 is changed by the control unit 30. The direction in which the position is changed intersects with the direction connecting the first mirror element 11 and the third mirror element 23, for example. The direction in which the position is changed further intersects with the direction connecting the second mirror element 12 and the third mirror element 23. Thereby, the second state ST2 is formed.

As shown in FIGS. 26B and 26D, the second resonator length L2 in the second state ST2 is shorter than the first resonator length L1.

Also in the resonator 152, the resonance frequency can be greatly shifted. High stability is obtained at the resonance frequency.

FIG. 27A and FIG. 27B are schematic views illustrating another resonator according to the fifth embodiment.
These figures correspond to the first state ST1.
As shown in FIG. 27A, another resonator 153 according to this embodiment includes a first mirror 10, a second mirror 20, a first spacer 50, a second spacer 60, a control unit 30, and the like. ,including. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11, the second mirror element 12, the fifth mirror element 15, and the like). The second mirror 20 includes a plurality of mirror elements 20e (for example, a third mirror element 23 and a fourth mirror element 24). The rest is the same as the resonator 151.

A part of the light Li that has entered the first mirror element 11 passes through the first mirror element 11, is reflected by the third mirror element 23, is then reflected by the fourth mirror element 24, and is then reflected by the fifth mirror. Reflected by the element 15, then reflected by the second mirror element 12 and then incident on the first mirror element 11. A part of the light LL passes through the first mirror element 11 and is emitted to the outside.

The first surface 50a of the first spacer 50 is inclined with respect to the XY plane (a plane perpendicular to the Z-axis direction), and the second surface 60a of the second spacer 60 is in the XY plane. It is inclined with respect to it. The relative position of the second spacer 60 with respect to the first spacer 50 is changed by the control unit 30. Thereby, the second state ST2 is formed. The second resonator length L2 in the second state ST2 is different from the first resonator length L1.

FIG. 28A and FIG. 28B are schematic views illustrating another resonator according to the fifth embodiment.
These figures correspond to the first state ST1.
As shown in FIG. 28A, another resonator 154 according to this embodiment includes a first mirror 10, a second mirror 20, a first spacer 50, a second spacer 60, a control unit 30, and the like. ,including. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11, the second mirror element 12, the fifth mirror element 15, and the like). The second mirror 20 includes a plurality of mirror elements 20e (for example, a third mirror element 23, a fourth mirror element 24, a sixth mirror element 26, etc.). The rest is the same as the resonator 151.

A part of the light Li that has entered the first mirror element 11 passes through the first mirror element 11, is reflected by the third mirror element 23, is then reflected by the fourth mirror element 24, and is then reflected by the sixth mirror. Reflected by the element 26, then reflected by the fifth mirror element 15, then reflected by the second mirror element 12, and then incident on the first mirror element 11. A part of the light LL passes through the first mirror element 11 and is emitted to the outside.

Also in the resonators 153 and 154, the resonance frequency can be greatly shifted. High stability is obtained at the resonance frequency.

(Sixth embodiment)
FIGS. 29A to 29D are schematic views illustrating another resonator according to the sixth embodiment.
FIG. 29A and FIG. 29C correspond to the first state ST1. FIG. 29B and FIG. 29D correspond to the second state ST2.

As illustrated in FIG. 29A, the resonator 161 according to the present embodiment includes the first mirror 10, the second mirror 20, the first spacer 50, the second spacer 60, and the control unit 30. Including. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11 and the second mirror element 12). The second mirror 20 includes a plurality of mirror elements 20e (for example, a third mirror element 23 and a fourth mirror element 24). Other than this, for example, it is the same as the resonator 110. In the resonator 161, a fixing part 81, a container 80, and a temperature adjustment element 82 may be provided. In these drawings, the fixing portion 81, the container 80, and the temperature adjustment element 82 are omitted.

In the resonator 161, for example, the Z-axis direction is, for example, a direction connecting the center of the first mirror 10 and the center of the second mirror 20 in one state (for example, the first state ST1). In this example, the center of the first mirror 10 is the midpoint between the first mirror element 11 and the second mirror element 12. The center of the second mirror 20 is the midpoint between the third mirror element 23 and the fourth mirror element 24. The direction connecting these midpoints is the Z-axis direction.

In the resonator 161, the first mirror element 11, the second mirror element 12, the third mirror element 23, and the fourth mirror element 24 are plane mirrors. The angle between the plane (plane) including the second mirror element 12 and the plane (plane) including the first mirror element 11 is, for example, 30 degrees. The angle between the plane (plane) including the fourth mirror element 24 and the plane (plane) including the third mirror element 23 is, for example, 30 degrees.

The second mirror element 12 is aligned with the first mirror element 11 along the X-axis direction. The fourth mirror element 24 is aligned with the third mirror element 23 along the X-axis direction. The fourth mirror element 24 is aligned with the second mirror element 12 along the Z-axis direction. The third mirror element 23 is aligned with the first mirror element 11 along the Z-axis direction. In the first state ST1, these mirror elements are arranged in the XZ plane.

As shown in FIG. 29A, the light Li is incident on the first mirror element 11. A part of the light Li LL passes through the first mirror element 11 and then enters the third mirror element 23. The light LL is reflected by the third mirror element 23. The incident angle in the third mirror element 23 is 15 degrees, and the reflection angle is 15 degrees. The light LL reflected by the third mirror element 23 travels toward the second mirror element 12. The light LL is reflected by the second mirror element 12. The incident angle in the second mirror element 12 is 15 degrees and the reflection angle is 15 degrees. The light LL reflected by the second mirror element 12 travels toward the fourth mirror element 24. The light LL is reflected by the fourth mirror element 24. The incident angle at the fourth mirror element 24 is 15 degrees and the reflection angle is 15 degrees. The light LL reflected by the fourth mirror element 24 travels toward the first mirror element 11. The light LL is incident on the first mirror element 11. A part of the light LL incident on the first mirror element 11 is emitted to the outside. In the above, the incident angle in a mirror element is an angle between the direction perpendicular to the surface of the mirror element and the light LL incident on the mirror element. The reflection angle is an angle between a direction perpendicular to the surface of the mirror element and the light LL reflected by the mirror element.

In the resonator 161, the first mirror 10 and the second mirror 20 form, for example, a bowtie type optical resonator. The bow tie type optical resonator is one of ring type resonators.

In the first state ST1, the distance between the first mirror element 11 and the third mirror element 23 (distance on the optical path) is, for example, 34.8076 mm. The distance (distance on the optical path) between the third mirror element 23 and the second mirror element 12 is 40.1924 mm. The distance (distance on the optical path) between the second mirror element 12 and the fourth mirror element 24 is, for example, 34.8076 mm. The distance (distance on the optical path) between the fourth mirror element 24 and the first mirror element 11 is 40.1924 mm. In the first state ST1, the first resonator length L1 is the sum of these distances and is 150 mm. In the first state ST 1, one side surface of the second spacer 60 is continuous with one side surface of the first spacer 50.

As shown in FIG. 29C, the first surface 50a of the first spacer 50 is inclined with respect to the XY plane (a plane perpendicular to the Z-axis direction). The two surfaces 60a are inclined with respect to the XY plane. For example, the angle between the first surface 50a of the first spacer 50 (the second surface 60a of the second spacer 60) and the XY plane is, for example, 0.022 degrees. For example, the first surface 50a and the second surface 60a are set perpendicular to the direction of gravity. For example, the relative position of the second spacer 60 with respect to the first spacer 50 is changed by the control unit 30. The position is changed along the first surface 50a. When the position is changed (moving), the control unit 30 contacts the second spacer 60. After changing the position (after movement), the control unit 30 is separated from the second spacer 60. Thereby, the second state ST2 is formed.

As shown in FIG. 29 (d), in the second state ST2, one of the side surfaces of the second spacer 60 is discontinuous with one side surface of the first spacer 50.

As shown in FIGS. 29B and 29D, the second resonator length L2 in the second state ST2 is shorter than the first resonator length L1. For example, the difference between the position of the second spacer 60 in the second state ST2 and the position of the second spacer 60 in the first state ST1 (the length along the first surface 50a, for example, relative to the direction of gravity The length along the vertical direction is 0.475 mm, for example.

The length along the Z-axis direction between the first mirror element 11 and the third mirror element 23 in the second state ST2, and the Z between the first mirror element 11 and the third mirror element 23 in the first state ST1. The difference between the length along the axial direction is 0.475 × sin (0.022 degrees) mm, which is about 0.00018 mm. The length along the Z-axis direction between the second mirror element 12 and the fourth mirror element 24 in the second state ST2, and the Z between the second mirror element 12 and the fourth mirror element 24 in the first state ST1. The difference between the length along the axial direction is 0.475 × sin (0.022 degrees) mm, which is about 0.00018 mm.

The incident angle at each of the plurality of mirror elements in the second state ST2 is the same as the incident angle at each of the plurality of mirror elements in the first state ST1. The reflection angle in each of the plurality of mirror elements in the second state ST2 is the same as the reflection angle in each of the plurality of mirror elements in the first state ST1. In one of the plurality of mirror elements, the position where the light Li is incident is different between the first state ST1 and the second state ST2. The second resonator length L2 in the second state ST2 is a distance between the first mirror element 11 and the third mirror element 23 (a distance on the optical path, 34.8075 mm), the third mirror element 23, and the second mirror length 23. The distance between two mirror elements 12 (distance on the optical path, 40.1922 mm) and the distance between the second mirror element 12 and the fourth mirror element 24 (distance on the optical path, 34.8075 mm) ) And the distance between the fourth mirror element 24 and the first mirror element 11 (the distance on the optical path, 40.1922 mm). The second resonator length L2 is 149.9994 mm.

Suppose that one of resonance frequencies ν (first resonance frequency) corresponding to the first resonator length L1 (resonator length before the resonator length is changed) is 247 THz. The difference (frequency shift amount Δν) between the resonance frequency (second resonance frequency) corresponding to the second resonator length L2 (resonator length after the resonator length has changed) and the first resonance frequency is about 1 GHz. It is. In the embodiment, the resonance frequency can be shifted greatly. Also in this example, before and after the change in the resonator length, the external force that causes the frequency instability is suppressed from being applied to the resonator. High stability is obtained at the resonance frequency.

FIG. 30A to FIG. 30D are schematic views illustrating another resonator according to the sixth embodiment.
FIG. 30A and FIG. 30C correspond to the first state ST1. FIG. 30B and FIG. 30D correspond to the second state ST2.

As shown in FIG. 30A, another resonator 162 according to this embodiment includes a first mirror 10, a second mirror 20, a first spacer 50, a second spacer 60, a control unit 30, and the like. ,including. The first mirror 10 includes a plurality of mirror elements 10e (for example, the first mirror element 11 and the second mirror element 12). The second mirror 20 includes a plurality of mirror elements 20e (for example, a third mirror element 23 and a fourth mirror element 24). In the resonator 162, a fixing part 81, a container 80, and a temperature adjustment element 82 may be provided. In these drawings, the fixing portion 81, the container 80, and the temperature adjustment element 82 are omitted.

In the resonator 162, the first mirror element 11, the second mirror element 12, the third mirror element 23, and the fourth mirror element 24 are plane mirrors. The angle between the plane (plane) including the second mirror element 12 and the plane (plane) including the first mirror element 11 is, for example, 60 degrees. The angle between the plane (plane) including the fourth mirror element 24 and the plane (plane) including the third mirror element 23 is, for example, 60 degrees.

30A, the light Li is incident on the first mirror element 11 in the first state ST1. A part of the light Li LL passes through the first mirror element 11, is reflected by the second mirror element 12, and travels toward the third mirror element 23. The light LL is reflected by the third mirror element 23 and travels toward the fourth mirror element 24. The light LL is reflected by the fourth mirror element 24 and travels toward the first mirror element 11. A bowtie type optical resonator is formed.

In the first state ST1, the distance between the first mirror element 11 and the second mirror element 12 (distance on the optical path) is 25 mm. The distance (distance on the optical path) between the second mirror element 12 and the third mirror element 23 is 50 mm. The distance (distance on the optical path) between the third mirror element 23 and the fourth mirror element 24 is 25 mm. The distance (distance on the optical path) between the fourth mirror element 24 and the first mirror element 11 is 50 mm. In the first state ST1, the first resonator length L1 corresponds to the sum of these distances and is 150 mm. In the first state ST 1, one side surface of the second spacer 60 is continuous with one side surface of the first spacer 50.

As shown in FIG. 30C, the first surface 50a of the first spacer 50 is inclined with respect to the XY plane (a plane perpendicular to the Z-axis direction). The two surfaces 60a are inclined with respect to the XY plane. For example, the angle between the first surface 50a of the first spacer 50 (the second surface 60a of the second spacer 60) and the XY plane is, for example, 0.022 degrees. For example, the first surface 50a and the second surface 60a are set perpendicular to the direction of gravity. For example, the relative position of the second spacer 60 with respect to the first spacer 50 is changed by the control unit 30. The position is changed along the first surface 50a. When the position is changed (moving), the control unit 30 contacts the second spacer 60. After changing the position (after movement), the control unit 30 is separated from the second spacer 60. Thereby, the second state ST2 is formed.

30 (d), in the second state ST2, one side surface of the second spacer 60 is discontinuous with one side surface of the first spacer 50.

30 (b) and 30 (d), the second resonator length L2 in the second state ST2 is shorter than the first resonator length L1. For example, the difference between the position of the second spacer 60 in the second state ST2 and the position of the second spacer 60 in the first state ST1 (the length along the first surface 50a, for example, relative to the direction of gravity The length along the vertical direction) is, for example, 0.045 mm.

The distance (the distance along the Z-axis direction) between the third mirror element 23 and the first mirror element 11 in the second state ST2, and the third mirror element 23 and the first mirror element 11 in the first state ST1 The difference between the distance (the distance along the Z-axis direction) is 0.45 × sin (0.022 degrees) mm, which is about 0.00017 mm. The distance between the fourth mirror element 24 and the second mirror element 12 in the second state ST2 (the distance along the Z-axis direction) and the fourth mirror element 24 and the second mirror element 12 in the first state ST1 The difference between the distance (the distance along the Z-axis direction) is 0.45 × sin (0.022 degrees) mm, which is about 0.00017 mm.

The incident angle at each of the plurality of mirror elements in the second state ST2 is the same as the incident angle at each of the plurality of mirror elements in the first state ST1. The reflection angle in each of the plurality of mirror elements in the second state ST2 is the same as the reflection angle in each of the plurality of mirror elements in the first state ST1. In one of the plurality of mirror elements, the position where the light Li is incident is different between the first state ST1 and the second state ST2. In the second state ST2, the distance between the first mirror element 11 and the second mirror element 12 (distance on the optical path) is 24.998 mm. The distance (distance on the optical path) between the second mirror element 12 and the third mirror element 23 is 49.9998 mm. The distance (distance on the optical path) between the third mirror element 23 and the fourth mirror element 24 is 25 mm. The distance (distance on the optical path) between the fourth mirror element 24 and the first mirror element 11 is 49.9998 mm. In the second state ST2, the second resonator length L2 corresponds to the sum of these distances and is 1499.9994 mm.

Suppose that one of resonance frequencies ν (first resonance frequency) corresponding to the first resonator length L1 (resonator length before the resonator length is changed) is 247 THz. The difference (frequency shift amount Δν) between the resonance frequency (second resonance frequency) corresponding to the second resonator length L2 (resonator length after the resonator length has changed) and the first resonance frequency is about 1 GHz. It is. Also in the resonator 162, the resonance frequency can be greatly shifted. Also in this example, before and after the change of the resonator length, the external force that causes the frequency instability is suppressed from being applied to the resonator, so that high stability can be obtained at the resonance frequency.

In the fifth and sixth embodiments described above, the first mirror 10 includes a plurality of mirror elements 10e (such as the first mirror element 11, the second mirror element 12, and the fifth mirror element 15). The positions of the plurality of mirror elements 10e with respect to the first spacer 50 are fixed. For example, the plurality of mirror elements 10 e are physically coupled to the first spacer 50. For example, the plurality of mirror elements 10e may be physically coupled to each other, and at least one of the plurality of mirror elements 10e may be physically coupled to the first spacer 50. One of the plurality of mirror elements 10e included in the first mirror 10 (for example, the first mirror element 11) and another one of the plurality of mirror elements 10e included in the first mirror 20 (for example, the second mirror element 12). ) Intersects the first direction (Z-axis direction connecting the first mirror 10 in the first state ST1 and the second mirror 20 in the first state ST1).

In these embodiments, the second mirror 20 may include a plurality of mirror elements 20e (such as the third mirror element 23, the fourth mirror element 24, and the sixth mirror element 26). The positions of the plurality of mirror elements 20e with respect to the second spacer 60 are fixed. For example, the plurality of mirror elements 20 e are physically coupled to the second spacer 60. For example, the plurality of mirror elements 20e may be physically coupled to each other, and at least one of the plurality of mirror elements 20e may be physically coupled to the second spacer 60. One of the plurality of mirror elements 20e included in the second mirror 20 (for example, the third mirror element 23) and another one of the plurality of mirror elements 20e included in the second mirror 20 (for example, the fourth mirror element 24). ) Intersects with the first direction (Z-axis direction).

In the fifth embodiment and the sixth embodiment, the first spacer 50 has a first surface 50 a facing the second spacer 60. The first surface 50a is inclined with respect to the first direction. The second spacer 60 has a second surface 60a. The second surface 60a faces the first spacer 50 and extends along the first surface 50a.

For example, in the fifth embodiment and the sixth embodiment, the first position of the second spacer 60 relative to the first spacer 50 in the first state ST1 is the first position of the second spacer 60 in the second state ST2. This is different from the second position relative to the spacer 50. The direction connecting the first position and the second position intersects at least a part of the optical path formed between the first mirror 10 and the second mirror 20 in the first state ST1. For example, the direction connecting the first position and the second position is one of the plurality of mirror elements 10e included in the first mirror 10 in the first state ST1 and the plurality of mirror elements included in the second mirror 20 in the first state ST1. It intersects with the direction connecting one of the mirror elements 20e.

The direction connecting the first position and the second position intersects at least one of “a plurality of connecting directions” (described below). Each of the “plurality of connecting directions” includes “one or more mirror elements” included in the first mirror 10 in the first state ST1 and “1” included in the second mirror 20 in the first state ST1. Each of the one or more mirror elements ".

For example, the position of at least one of the first spacer 50 and the second spacer 60 is changed. This change is performed by the control unit 30, for example. When one mirror element is provided in the first mirror 10 and one mirror element is provided in the second mirror 20, the direction in which the position is changed is the direction connecting the first mirror 10 and the second mirror 20. Intersect. In the case where one mirror element is provided in the first mirror 10 and the second mirror 20 includes a plurality of mirror elements, the direction in which the position is changed is the plurality of directions included in the first mirror 10 and the second mirror 20. It intersects one of a plurality of directions connecting any of the mirror elements. When the first mirror 10 includes a plurality of mirror elements and the second mirror 20 includes a plurality of mirror elements, the direction in which the position change is performed is any one of the plurality of mirror elements included in the first mirror 10 and the first mirror 10. It intersects with any one of a plurality of mirror elements included in the two mirrors 20 and any one of a plurality of directions to be connected.

The description with reference to the

resonators

151 and 152 regarding the change direction of the spacer position is similarly applied to other resonators (for example, the

resonators

153, 154, 161, and 162).

For example, in the resonator 151, the first mirror element 11 is the first mirror 10, the third mirror element 23 is the second mirror 20, the second mirror element 12 is the third mirror, and the fourth mirror element. You may consider that 24 is a 4th mirror. In this case, on the optical path between the first mirror 10 (first mirror element 11) and the second mirror 20 (third mirror element 23), the third mirror (second mirror element 12) and the fourth mirror ( It is assumed that the fourth mirror element 24) is arranged.

The resonator according to the fifth embodiment, the resonator according to the sixth embodiment, and a modified resonator of those resonators can be used, for example, in a light source device or a frequency filter.

According to the embodiment, it is possible to provide a resonator, a light source device, and a frequency filter having a variable resonance frequency.

In the present specification, “vertical” and “parallel” include not only strictly vertical and strictly parallel, but also include, for example, variations in the manufacturing process, and may be substantially vertical and substantially parallel. It ’s fine.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific configuration of each element such as a mirror, a spacer, a control unit, a fixed unit, and a temperature adjustment element included in the resonator, the present invention is similarly implemented by appropriately selecting from a known range by those skilled in the art. As long as the same effect can be obtained, it is included in the scope of the present invention.

Further, combinations of any two or more elements of each specific example within the technically possible range are also included in the scope of the present invention as long as they include the gist of the present invention.

In addition, all resonators, light source devices and frequency filters that can be implemented by those skilled in the art based on the resonators, light source devices, and frequency filters described above as embodiments of the present invention are also included in the present invention. As long as the gist is included, it belongs to the scope of the present invention.

In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 ... 1st mirror, 10a ... 1st mirror surface, 10c ... 1st center, 10e ... Mirror element, 10r ... Outer edge part, 11 ... 1st mirror element, 12 ... 2nd mirror element, 15 ... 5th mirror element, 17 ... first layer, 18 ... second layer, 20 ... second mirror, 20a ... second mirror surface, 20c ... second center, 20e ... mirror element, 20r ... outer edge, 23 ... third mirror element, 24 ... second 4 mirror elements, 25 ... spacer member, 26 ... sixth mirror element, 27 ... third layer, 28 ... fourth layer, 30 ... control unit, 31-34 ... first to fourth moving devices, 31a-34a ... first 1st to 4th micrometer heads, 31b to 34b ... 1st to 4th piezo actuators, 50 ... 1st spacer, 50a ... 1st surface, 51 ... 1st connection part, 51a ... surface, 52 1st intermediate part, 52a ... surface, 55 ... spacer, 55a, 55b ... 1st, 2nd surface, 60 ... 2nd spacer, 60a ... 2nd surface, 61 ... 2nd connection part, 61a ... surface, 62 ... 1st 2 intermediate part, 62a ... surface, 71 ... light source, 72 ... beam splitter, 73 ... frequency control device, 74 ... frequency shifter, 75 ... light source, 80 ... container, 81 ... fixed part, 82 ... temperature adjustment element, Δd ... distance 110, 111, 112a to 112c, 113, 114a, 114b, 115, 116, 120 to 125, 131 to 135, 146, 147, 151 to 154, 161, 162 ... resonator, 210, 211 ... light source device, 310 ... frequency filter, Ar, Ar1, Ar2 ... arrows, L1, L2 ... first and second resonator lengths, Li, LL ... light, Md ... direction Direction, Rs1, Rs2 ... first and second resonators, ST1, ST2 ... first and second states, d1, d2 ... distance

Claims

A first mirror;
A second mirror,
A first spacer provided between the first mirror and the second mirror and in contact with the first mirror;
A second spacer provided between the first spacer and the second mirror and in contact with the second mirror;
With
The first resonator length formed by the first mirror and the second mirror in a first state where the first spacer and the second spacer are in contact with each other is such that the first spacer and the second spacer are A resonator that is different from a second resonator length formed by the first mirror and the second mirror in a second state that is in contact and different from the first state.
The first position of the second spacer relative to the first spacer in the first state is different from the second position of the second spacer relative to the first spacer in the second state;
The resonator according to claim 1, wherein a direction connecting the first position and the second position intersects a first direction connecting the first mirror in the first state and the second mirror in the first state. .
The first spacer has a first surface facing the second spacer,
The first surface intersects the first direction;
The resonator according to claim 1, wherein the second spacer has a second surface that faces the first spacer and extends along the first surface.
The resonator according to claim 3, wherein the first surface is inclined with respect to the first direction.
The first spacer is in contact with at least one of an outer edge and a side surface of the first mirror;
The resonator according to any one of claims 1 to 4, wherein the second spacer is in contact with at least one of an outer edge portion and a side surface of the second mirror.
In the first state, the first spacer and the second spacer form a mechanically stable state by forming a contact state of at least one of point contact, line contact, and surface contact,
In the second state, the first spacer and the second spacer form a mechanically stable state by forming a contact state of at least one of point contact, line contact, and surface contact. Item 6. The resonator according to any one of Items 1 to 5.
The resonator according to any one of claims 1 to 6, wherein at least one of the first spacer and the second spacer includes two or more spacers.
The resonator according to any one of claims 1 to 7, further comprising a control unit that changes a position of at least one of the first spacer and the second spacer.
A first mirror;
A second mirror,
A first spacer provided between the first mirror and the second mirror and in contact with the first mirror;
With
The first position of the second mirror relative to the first spacer in the first state is:
Unlike the second position of the second mirror relative to the first spacer in the second state,
The first resonator length formed by the first mirror and the second mirror in the first state is the second resonator length formed by the first mirror and the second mirror in the second state. A different resonator.
The resonator according to claim 9, wherein a direction connecting the first position and the second position intersects a first direction connecting the first mirror in the first state and the second mirror in the first state. .
The resonator according to claim 9 or 10, further comprising a controller that changes a position of at least one of the first spacer or the second mirror.
The resonator according to any one of claims 1 to 11, wherein the first spacer is tubular.
The resonator according to any one of claims 1 to 12, wherein the second spacer is tubular.
The resonator according to any one of claims 1 to 13, wherein a thermal expansion coefficient of the first spacer at 20 ° C is 10 -6 K -1 or less.
The resonator according to any one of claims 1 to 14, wherein a thermal expansion coefficient of the second spacer at 20 ° C is 10 -6 K -1 or less.
The first mirror and the second mirror are:
(A) A first relationship in which one of the first mirror and the second mirror is a plane mirror, and the other of the first mirror and the second mirror is a concave mirror,
(B) Each of the first mirror and the second mirror is a concave relationship, a second relationship,
(C) a third relationship in which each of the first mirror and the second mirror is a plane mirror; and
(D) A fourth relationship in which one of the first mirror and the second mirror is a convex mirror, and the other of the first mirror and the second mirror is a concave mirror,
The resonator according to any one of claims 1 to 15, wherein any one of the above is satisfied.
A first mirror comprising one or more mirror elements;
A second mirror comprising one or more mirror elements;
A first spacer provided between the first mirror and the second mirror and in contact with the first mirror;
A second spacer provided between the first spacer and the second mirror and in contact with the second mirror;
With
The first resonator length formed by the first mirror and the second mirror in a first state where the first spacer and the second spacer are in contact with each other is such that the first spacer and the second spacer are A resonator that is different from a second resonator length formed by the first mirror and the second mirror in a second state that is in contact and different from the first state.
The first position of the second spacer relative to the first spacer in the first state is different from the second position of the second spacer relative to the first spacer in the second state;
A direction connecting the first position and the second position intersects at least one of a plurality of connecting directions;
Each of the plurality of connecting directions includes the one or the plurality of mirror elements included in the first mirror in the first state, and the one or the plurality of mirror elements included in the second mirror in the first state. The resonator according to claim 17, wherein each of the plurality of mirror elements is connected.
A resonator according to any one of claims 1 to 18;
A light source whose frequency is locked to the resonator;
A light source device.
A frequency filter comprising the resonator according to any one of claims 1 to 18.