Optical power attenuator

Abstract

An optical power attenuator includes: a MEMS package storing a MEMS element that can control a reflection angle of light by a mirror; a capillary member provided to one end of a two-core optical fiber that transmits the light and that has an end surface on a side that inputs/outputs the light to the two-core optical fiber tilted at a predetermined angle relative to an optical axis of the two-core optical fiber; and a lens that causes a light emitted from one of the optical fibers of the two-core optical fiber to become incident on the MEMS element via the capillary member and guides the reflected light reflected by the mirror of the MEMS element to the other optical fiber of the two-core optical fiber.

Claims

1. An optical power attenuator, comprising: a microelectromechanical system (MEMS) package storing a MEMS element that can control a reflection angle of a light by a mirror; a capillary member that is provided to one end of a two-core optical fiber that transmits the light and has an end surface on a side that inputs/outputs the light to the two-core optical fiber tilted at a predetermined angle relative to an optical axis of the two-core optical fiber; and a lens that is interposed between the capillary member and the MEMS package and that causes a light emitted from one of the optical fibers of the two-core optical fiber to become incident on the MEMS element via the capillary member and guides the reflected light reflected by the mirror of the MEMS element to the other optical fiber of the two-core optical fiber; wherein a center axis of the lens and the optical axis of the two-core optical fiber are collinear and pass through a geometric center of a face of the MEMS package facing the lens, and in the MEMS package, the MEMS element is disposed in a position where a geometric center point of a reflecting surface of the mirror does not lie on the center axis of the lens and where the incident light from the lens is reflected toward the lens.

2. The optical power attenuator according to claim 1, wherein the MEMS package is configured so no wiring component that inputs a control signal to the MEMS element is included in a mounting space of the MEMS element.

3. The optical power attenuator according to claim 1, wherein the MEMS package is provided with an electrode pattern for inputting the control signal to the MEMS element from outside.

4. The optical power attenuator according to claim 1, wherein with a size of the MEMS package, a maximum outline is 3.5 mm or less.

5. The optical power attenuator according to claim 1, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

6. The optical power attenuator according to claim 1, wherein the two-core optical fiber is configured by an optical fiber of a cladding diameter of 100 m or less.

7. The optical power attenuator according to claim 2, wherein the MEMS package is provided with an electrode pattern for inputting the control signal to the MEMS element from outside.

8. The optical power attenuator according to claim 2, wherein with a size of the MEMS package, a maximum outline is 3.5 mm or less.

9. The optical power attenuator according to claim 3, wherein with a size of the MEMS package, a maximum outline is 3.5 mm or less.

10. The optical power attenuator according to claim 7, wherein with a size of the MEMS package, a maximum outline is 3.5 mm or less.

11. The optical power attenuator according to claim 2, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

12. The optical power attenuator according to claim 3, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

13. The optical power attenuator according to claim 4, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

14. The optical power attenuator according to claim 7, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

15. The optical power attenuator according to claim 8, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

16. The optical power attenuator according to claim 9, wherein the two-core optical fiber is configured by an optical fiber of a curvature radius of 10 mm or less.

17. The optical power attenuator according to claim 2, wherein the two-core optical fiber is configured by an optical fiber of a cladding diameter of 100 m or less.

18. The optical power attenuator according to claim 3, wherein the two-core optical fiber is configured by an optical fiber of a cladding diameter of 100 m or less.

19. The optical power attenuator according to claim 4, wherein the two-core optical fiber is configured by an optical fiber of a cladding diameter of 100 m or less.

20. The optical power attenuator according to claim 5, wherein the two-core optical fiber is configured by an optical fiber of a cladding diameter of 100 m or less.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 An explanatory view representing a configuration of an optical power attenuator of one or more embodiments.

(2) FIGS. 2A and 2B A representation of a configuration example of a MEMS package: FIG. 2A is a side view, and FIG. 2B is a plan view.

(3) FIGS. 3A and 3B A representation of a disposition of a mirror in a MEMS element: FIG. 3A is an explanatory view representing a state where the mirror is disposed in a center position, and FIG. 3B is an explanatory view representing a state where the mirror is disposed in a position eccentric from the center position.

(4) FIGS. 4A and 4B A representation of another configuration example of the MEMS package; FIG. 4A is a side view, and FIG. 4B is a bottom view.

(5) FIG. 5 An explanatory view representing a configuration of a conventional optical power attenuator.

DETAILED DESCRIPTION

(6) Embodiments of the present invention are described below together with the drawings. As illustrated in FIG. 1, an optical power attenuator 1 of one or more embodiments of the present invention, like the conventional one illustrated in FIG. 5, is provided with a MEMS package 12 storing a MEMS element 10, a capillary member 22 provided to one end of a two-core optical fiber 20, and a lens 30.

(7) The lens 30 is configured as a collimating lens and is disposed between the capillary member 22 and the MEMS element 10. Because of this, a light emitted from an IN-side optical fiber 20i among the two-core optical fiber 20 is converted into a collimated light (parallel light) at the lens 30 and becomes incident to the MEMS element 10 and a reflected light from the MEMS element 10 becomes incident to an OUT-side optical fiber 20o in a path different from an incoming path.

(8) Therefore, the incident light from the IN-side optical fiber 20i is attenuated according to a reflection angle of the light by a mirror in the MEMS element 10, becomes incident to the OUT-side optical fiber 20o, and is transmitted to another optical device via the OUT-side optical fiber 20o.

(9) Furthermore, in the optical power attenuator 1 of one or more embodiments, so centers of the MEMS package 12 and the capillary member 22 are aligned with a center axis (optical axis) A of the lens 30, the MEMS package 12, the lens 30, and the capillary member 22 are disposed coaxially.

(10) In contrast, an end surface on a lens-30 side of the capillary member 22, like the conventional one illustrated in FIG. 5, is configured to be tilted at a predetermined angle relative to an optical axis of the two-core optical fiber 20.

(11) Because of this, from the capillary member 22, the light from the IN-side optical fiber 20i is emitted diagonally relative to the optical axis of the two-core optical fiber 20 and this light becomes incident to the MEMS package 12 in a position eccentric from the center axis A of the lens 30.

(12) Therefore, in one or more embodiments, so the incident light from the lens 30 can be reflected in a desired direction at the mirror in the MEMS element 10, the MEMS element 10 is disposed in the MEMS package 12 in a position eccentric from a center position of the MEMS package.

(13) As a result, according to the optical power attenuator 1 of one or more embodiments, by positioning the MEMS package 12 relative to the lens 30 and the capillary member 22 by rotating the MEMS package 12 around the center axis A so the light from the IN-side optical fiber 20i becomes incident to a center position of the MEMS element 10, the reflection angle of the light by the MEMS element 10 can be set appropriately. Note that it is sufficient to perform this positioning of the MEMS package 12 around the center axis A when designing the optical power attenuator 1.

(14) Furthermore, because the MEMS package 12 need not be disposed in a position eccentric from the center axis A of the lens 30, a diameter R of an entirety of the optical power attenuator 1 can be made to correspond to a diameter of the lens 30.

(15) Therefore, according to the optical power attenuator 1 of one or more embodiments, a size can be decreased compared to the conventional optical power attenuator 5 illustrated in FIG. 5 and, by extension, an optical communication instrument built-in with the optical power attenuator 1 can be readily decreased in size.

(16) Here, in disposing the MEMS element 10 in the MEMS package 12 in the position eccentric from the center position of the MEMS package 12 as in one or more embodiments, for example, as illustrated in FIGS. 2A and 2B, it is sufficient to dispose the MEMS element 10 on a substrate 13 in the MEMS package 12 in a position eccentric from a center point Po of the substrate 13.

(17) Note that in FIGS. 2A and 2B, provided to the substrate 13 whereon the MEMS element 10 is mounted is a pair of positive and negative electrode pins 14 for applying to the MEMS element 10 a voltage for reflection-angle adjustment (in other words, for electrostatic-force generation). Furthermore, the MEMS element 10 and the substrate 13 are stored in a TO-CAN package configured by a TO header 15 and a TO cap 16, and the electrode pins 14 protrude to the outside from the TO header 15.

(18) Furthermore, in a situation of storing the optical power attenuator 1 in a case of an optical communication instrument such as an optical transceiver, to decrease a size of the optical communication instrument, not only a housing size of the optical power attenuator 1 but also a handling of an optical fiber that is used is an important element.

(19) Therefore, in the power optical attenuator 1 of one or more embodiments, as the IN-side optical fiber 20i and the OUT-side optical fiber 20o configuring the two-core optical fiber 20, so wiring is facilitated in the case of the optical communication instrument, an optical fiber with a small diameter and curvature radius is used.

(20) Specifically, with an optical power attenuator, generally, as an IN-side optical fiber 20i and an OUT-side optical fiber 20o, those with a curvature radius R of 30 mm, a cladding diameter of 125 m, and a wire of 250 m is used.

(21) In contrast, in one or more embodiments, as the IN-side optical fiber 20i and the OUT-side optical fiber 20o, an optical fiber with a cladding diameter of 100 m or less or a curvature radius of 10 mm or less is used. As a result, high-density fiber mounting in a narrow space is possible and a size decrease of the optical communication instrument using the optical power attenuator 1 can be realized.

(22) Note that as the optical fiber with the curvature radius of 10 mm or less, for example, ClearCurve ZBL Optical Fiber made by Corning can be mentioned and as the optical fiber with the cladding diameter of 100 m or less, for example, RC SMF made by Corning can be mentioned.

(23) Various embodiments of the present invention are described above, but the optical power attenuator of the present invention is not limited to the above embodiments and can be implemented with various modifications.

(24) For example, in one or more of the above embodiments, by disposing the MEMS element 10 in the MEMS package 12 in the position eccentric from the center position of the MEMS package 12 (in other words, the center axis A of the lens 30), desired reflection characteristics (in other words, attenuation characteristics) can be obtained even if the MEMS package 12 is disposed on the center axis A of the lens 30.

(25) In contrast, the MEMS element 10 may be disposed in the center position of the MEMS package 12 and, in the MEMS element 10, a mirror 18 may be disposed in a position eccentric from the center position of the MEMS element 10.

(26) That is, as illustrated in FIG. 3A, in the MEMS element 10, normally, the mirror 18 is normally disposed so a pivoting-center position supported by a beam 19 aligns with a center position P1 of the MEMS element 10. In contrast, as illustrated in FIG. 3B, so a pivoting-center position P2 of the mirror 18 is shifted from the center position P1 of the MEMS element 10, a position of the beam 19 supporting the mirror 18 is changed.

(27) Furthermore, by doing so, even if the MEMS element 10 is disposed in the center position in the MEMS package 12, the center position of the mirror 18 can be shifted from the center position of the MEMS package 12. Therefore, even if the MEMS element 10 is configured as illustrated in FIG. 3B, effects similar to those of one or more of the above embodiments can be obtained.

(28) Meanwhile, in one or more of the above embodiments, the MEMS package 12 is configured as the TO-CAN package and the voltage for driving the MEMS element 10 is input via the electrode pins 14 protruding from the TO header 15 of the MEMS package 12.

(29) Because of this, in a mounting space of the MEMS element 10 in the MEMS package 12, there is no need to provide a wiring component for applying the voltage, which is a control signal, to the MEMS element 10, and by this, the MEMS package 12 can be decreased in size.

(30) However, while the electrode pins 14 are used to connect to a drive circuit for inputting the control signal (drive voltage) to the MEMS package 12 and are suited to mounting the MEMS package 12 to a circuit board assembled with the drive circuit, to ensure a strength, a diameter needs to be increased.

(31) Because of this, when the electrode pins 14 are provided to the MEMS package 12, due to the diameter of the electrode pins 14, it becomes difficult to further decrease the size of the MEMS package 12.

(32) Therefore, to further decrease the size of the MEMS package 12 to decrease the size of the optical power attenuator 1 and, by extension, the optical communication instrument built-in with the optical power attenuator 1, it is favorable to configure the MEMS package 12 as illustrated in FIGS. 4A and 4B.

(33) That is, in a MEMS package 12A illustrated in FIGS. 4A and 4B, a voltage application line of applying the drive voltage to the MEMS element 10 is configured by a pair of through holes 14B that penetrates the substrate 13 and a header 15A. Moreover, on an outer wall (bottom surface) on a header-15A side of the MEMS package 12A, a pair of electrode patterns 14A connected to each through hole 14B is provided.

(34) According to the MEMS package 12A configured in this manner, because there is no need to provide the electrode pins 14, the size can be decreased compared to the MEMS package 12 illustrated in FIGS. 2A and 2B.

(35) Specifically, in optical power attenuators, an outermost diameter of a TO-CAN package currently being used is about 3 to 5 mm, but by configuring the MEMS package 12A as illustrated in FIGS. 4A and 4B, a maximum outer diameter can be made to be 3.5 mm or less. Moreover, in this situation, a shape of the MEMS package 12A can be made cylindrical or, as illustrated in FIGS. 4A and 4B, rectangular.

(36) Furthermore, as illustrated in FIG. 4B, by connecting electrode pins 14C or electrode lead frames (not illustrated) to the electrode patterns 14A, the MEMS package 12A can be used similarly to one configured by the TO-CAN package and the like.

(37) Furthermore, a plurality of functions had by one component in one or more of the above embodiments may be realized by a plurality of components and one function had by one component may be realized by a plurality of components. Moreover, a plurality of functions had by a plurality of components may be realized by one component and one function realized by a plurality of components may be realized by one configuration. Moreover, a portion of the configuration of one or more of the above embodiments may be omitted. Moreover, at least a portion of the configuration of one or more of the above embodiments may be added to or substituted in another configuration of one or more of the above embodiments. Note that all aspects included in the technical idea specified only by the text given in the scope of patent claims are one or more embodiments of the present invention.

(38) Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.

REFERENCE SIGNS LIST

(39) 1, 5 . . . optical power attenuator; 10 . . . MEMS element; 12, 12A . . . MEMS package; 13 . . . substrate; 14 . . . electrode pin; 14A . . . electrode pattern; 14B . . . through hole; 14C . . . electrode pin; 15 . . . TO header; 15A . . . header; 16 . . . TO cap; 18 . . . mirror; 19 . . . beam; 20 . . . two-core optical fiber; 20i . . . IN-side optical fiber; 20o . . . OUT-side optical fiber; 22 . . . capillary member; 30 . . . lens.