JP2011008177A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module that easily adjusts an angle of an optical filter provided in an optical path toward a specified optical element.SOLUTION: The optical filter 9 is provided between a photodiode 32 and a mirror 7. The optical filter 9 is supported from the first photodiode package 3. A casing side rotary holder 18 and a package side rotary holder 17 are arranged between a casing 1 and the package 3. The holders 18 and 17 has end faces 17a, 18a facing in contact with each other, having a shape of a part of a sphere. The holder 17 moves along the end face 18a, and the package 3 is thereby supported while varying the angle from the casing 1.

Description

  The present invention relates to an optical module in which an optical element is mounted and the optical element is coupled to an optical fiber, and more particularly to an optical module in which a plurality of optical elements are mounted.

  Conventionally, an optical module is equipped with a plurality of optical elements such as a photodiode for reception and a laser diode for transmission, and further includes an optical system such as a lens and a mirror, and each optical element is connected via the optical system. Optical modules that are coupled to a single optical fiber are known.

  Such an optical module has, for example, the following structure. That is, it has a casing in which a wavelength selective mirror and a plurality of optical elements are housed and an optical fiber extending from the outside is connected, and the plurality of optical elements are arranged around the mirror, for example, The light incident from the optical fiber is transmitted or reflected through the mirror and branched, and each light enters each optical element, or the light emitted from each optical element is transmitted through or reflected from the mirror and enters the optical fiber. The position has been adjusted to That is, the position of each optical element is adjusted so as to be optically coupled to the optical fiber via the mirror.

  In the optical module configured as described above, an optical filter may be provided on an optical path toward a specific optical element in order to obtain a desired optical signal. That is, of the incident optical signal, an optical signal having a specific wavelength is reflected by the mirror and incident on the optical filter. However, due to factors such as the mounting inclination of the mirror and the mounting inclination of the optical fiber casing, When the incident angle of the light beam is inclined, sufficient performance cannot be obtained. In general, an optical filter is formed by laminating several tens to several hundreds of dielectric thin films, and operates using interference between layers, so that the transmission characteristics of the optical filter greatly depend on the incident angle. In particular, an optical filter having a steep wavelength selection characteristic needs to have an incident angle in the vertical direction, and the transmission characteristic fluctuates with respect to incident light from an unexpected direction other than the vertical direction. FIG. 12 is a diagram illustrating a transmission loss graph of the optical filter. The transmission wavelength band fluctuates in the transmission characteristics when incident obliquely compared to the transmission characteristics when incident perpendicularly to the optical filter. Therefore, in order to appropriately obtain the desired characteristics, it is necessary to make light incident on the optical filter perpendicularly. That is, it is necessary to adjust the incident angle of light to the optical filter.

  On the other hand, conventionally, in an optical module having a casing in which an optical element and a set of optical systems are housed and an optical fiber extending from the outside is connected, an angle adjusting mechanism is provided between the optical system and the optical fiber. Thus, a technique for correcting the angular deviation has been proposed (see, for example, Patent Document 1).

JP-A-7-218775

  However, according to the technique proposed in the above-mentioned Patent Document 1, the mounting angle of the optical fiber can be changed with respect to the casing. When it is desired to adjust the angle of the optical filter provided on the optical path, it is difficult to apply.

  The present invention has been made to solve the above-described problems. In an optical module including a plurality of optical elements, the optical module of the present invention can be applied to a specific optical element without affecting the optical adjustment of other optical elements. It is an object of the present invention to provide an optical module that can easily adjust the angle of an optical filter provided on an optical path toward the optical path.

  In order to solve the above-described problems and achieve the object, an optical module according to the present invention includes a casing to which an optical fiber is connected, a plurality of packages mounted on the casing and each mounting an optical element, and a casing. An optical filter provided between the at least one optical element and the optical system in an optical module that is optically coupled to the optical fiber via the optical system. The optical filter is supported from the package, and a fixed holder provided in the casing and a movable holder provided in the package and assembled with the fixed holder are disposed between the casing and the fixed filter and the movable holder. The end faces facing each other are part of a spherical surface, and the movable holder moves along the end faces to Characterized by changing the angle supporting the over-di from the casing.

  According to the present invention, an optical module having a plurality of packages each mounting an optical element, supported from the package, and provided between the casing and the fixed holder provided in the casing and the package. A movable holder that is assembled with the fixed holder, and the fixed holder and the movable holder have end faces that face each other in a shape of a part of a spherical surface, and the movable holder moves along the end surface to Since it is supported from the casing so that the angle can be changed, the angle of the optical filter provided on the optical path toward the specific optical element can be easily adjusted without affecting the optical adjustment of other optical elements. .

FIG. 1 is an exploded perspective view of a part of the first embodiment of an optical module according to the present invention. FIG. 2 is a longitudinal sectional view of Embodiment 1 of the optical module according to the present invention. FIG. 3 is a front view of the package side rotating holder. FIG. 4 is a side view of the package side rotating holder. FIG. 5 is a cross-sectional view taken along the line D-D ′ in FIG. 3. FIG. 6 is a front view of the casing side rotating holder. FIG. 7 is a side view of the casing-side rotation holder. FIG. 8 is a sectional view taken along line E-E ′ of FIG. 6. FIG. 9 is a view for explaining a state in which the first photodiode package changes the mounting angle with respect to the casing, and is a partial cross-sectional view showing a state before the angle is changed. FIG. 10 is a view for explaining a state in which the first photodiode package changes the mounting angle with respect to the casing, and is a partial cross-sectional view of the state after the angle change. FIG. 11 is a longitudinal sectional view of an optical module according to a second embodiment of the present invention. FIG. 12 is a diagram illustrating a transmission loss graph of the optical filter.

  Embodiments of an optical module according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view of a part of the first embodiment of an optical module according to the present invention. FIG. 2 is a longitudinal sectional view of Embodiment 1 of the optical module according to the present invention. 1 and 2, an optical module 101 according to the present embodiment includes a casing 1 to which an optical fiber 2 is connected, and three TO-type metal CAN packages that are attached to the casing 1 and each mount an optical element. It has a TO-CAN package. Note that the TO-CAN package is a device in which elements are housed in a can-shaped metal called a metal CAN.

  Specifically, the three TO-CAN packages have the same reception as the first photodiode package (hereinafter referred to as the first PD package) 3 on which the receiving photodiode (hereinafter referred to as PD) 32 is mounted as the optical element. A second photodiode package (hereinafter referred to as a second PD package) 4 on which a photodiode (hereinafter referred to as PD) 42 is mounted and a laser diode package (hereinafter referred to as an LD) 52 as an optical element mounted thereon Hereinafter, LD package) 5.

  The inside of the casing 1 is hollow, and two flat mirrors 7 and 8 constituting the optical system are accommodated. The mirror 7 and the mirror 8 are supported by a mirror holder 6 disposed in the approximate center of the casing 1 such that the principal surfaces of the mirror 7 and the mirror 8 are 90 degrees. In the casing 1, four mounting holes 1a to 1d are opened approximately 90 degrees apart from each other about the mirrors 7 and 8. The optical fiber 2 and the three packages 3, 4 and 5 are attached to the attachment holes 1a to 1d, respectively. The optical fiber 2 is connected to the casing 1 such that the fiber ferrule 10 provided at the tip is inserted into the mounting hole 1a with the flange portion provided at the cable end abutting against the outer surface of the casing 1.

  The first PD package 3 is disposed in the immediate vicinity of the PD 32 on the optical path from the mirror 7 to the PD 32, the stem 31 on which the PD 32 is mounted, the lead pin 33 that is electrically connected to the PD 32 and extends to the outside through the stem 31. It has a lens 35 that collects light, and a lens cap 34 that has a substantially bottomed cylindrical can shape, covers the PD 32, makes the inside a sealed space, and supports the lens 35. Note that a bias is applied to the PD 32 from the outside via the lead pin 33.

  The first PD package 3 of the present embodiment further has a bottomed cylindrical shape larger than the lens cap 34 and the optical filter 9 disposed on the optical path from the mirror 7 to the lens 35 and is coaxially stacked on the lens cap 34. And a filter cap 16 that supports the optical filter 9. The optical filter 9 is fixed to the hole opened at the bottom of the filter cap 16 with, for example, an adhesive. The filter cap 16 is fixed by projection welding or YAG welding so that the flange portion formed at the opening edge portion overlaps the lens cap 34. The optical filter 9 is disposed so as to be orthogonal to the optical path from the mirror 7 to the lens 35, and the light reflected by the mirror 7 enters the optical filter 9 at a right angle (angle B in FIG. 2).

  In addition, between the first PD package 3 and the casing 1, there is provided an attachment angle variable means for changing the attachment angle of the first PD package 3 with respect to the casing 1. The mounting angle varying means includes an annular casing side rotation holder (fixed holder) 18 fixed around the mounting hole of the casing 1 by YAG welding, and a cylindrical package fixed to the outer peripheral surface of the filter cap 16 by YAG welding. It is comprised from the side rotation holder 17 (movable holder).

  FIG. 3 is a front view of the package side rotation holder 17. FIG. 4 is a side view of the package side rotation holder 17. FIG. 5 is a cross-sectional view taken along the line D-D ′ in FIG. 3. FIG. 6 is a front view of the casing-side rotation holder 18. FIG. 7 is a side view of the casing-side rotation holder 18. FIG. 8 is a cross-sectional view taken along the line EE of FIG. 9 and 10 are views for explaining a state in which the first PD package 3 changes the mounting angle with respect to the casing 1, and FIG. 9 is a partial cross-sectional view of the state before the angle change. 10 is a partial cross-sectional view of the state after the angle change.

  3 to 10, the casing-side rotary holder 18 and the package-side rotary holder 17 have end faces that face each other in a part of a spherical surface, and the package-side rotary holder 17 slides along the end face. Thus, the first PD package 3 is supported from the casing 1 so that the angle can be changed. That is, an end face (opening edge outer side) 17a that abuts the casing side rotating holder 18 is formed outside the opening edge of one side of the cylindrical package side rotating holder 17, while the casing side rotation forming an annular shape is formed. An end surface (inner peripheral surface) 18a that faces the package-side rotating holder 17 is formed on the inner periphery of the holder 18. The end surface 17a is a part of a spherical surface F that protrudes outward, and the end surface 18a is inward. A part of the concave spherical surface F is formed, and both end surfaces 17a and 18a are slidable on the spherical surface F (FIGS. 9 and 10). Thereby, the attachment angle of the 1st PD package 3 with respect to the casing 1 can be changed.

  Returning to FIG. 2, the second PD package 4 has substantially the same shape as the first PD package 3, and a stem 41 on which the PD 42 is mounted, and a lead pin 43 that is electrically connected to the PD 42 and extends to the outside through the stem 41. And a lens 45 disposed on the optical path from the mirror 8 to the PD 42, and a lens cap 44 that has a substantially bottomed cylindrical can shape, covers the PD 42, makes the inside a sealed space, and supports the lens 45. ing. A bias is applied to the PD 42 from the outside via a lead pin 43. The second PD package 4 is fixed to the mounting hole 1 c of the casing 1 while adjusting the position with the adhesive 13.

  The LD package 5 includes a stem 51 on which the LD 52 is mounted, a lead pin 53 that is electrically connected to the LD 52 and extends to the outside through the stem 51, and a lens 55 that is disposed on the optical path from the mirror 8 to the LD 52. The lens cap 54 has a substantially cylindrical shape with a bottom and covers the LD 52 to make the inside a sealed space and support the lens 55.

  Between the LD package 5 and the casing 1, there is provided attachment position variable means for making the LD package 5 movable in the axial direction (optical axis direction) with respect to the casing 1. The mounting position varying means includes a cylindrical casing side slide holder 12 fixed to the mounting position of the casing 1 by welding, and a cylindrical package side slide holder 11 provided so as to surround the outer periphery of the LD package 5. It is configured. The package side slide holder 11 is fitted into the casing side slide holder 12, and the outer peripheral surface of the package side slide holder 11 is slidably in contact with the inner peripheral surface of the casing side slide holder 12. Slides along the inner peripheral surface of the casing-side slide holder 12 to support the LD package 5 so as to be movable in the axial direction from the casing 1.

  In the first PD package 3 of the present embodiment, the mounting angle can be changed along the spherical surface by the functions of the package side rotation holder 17 and the casing side rotation holder 18. The filter cap 16 may be slidable between the package-side slide holder 11 and the casing-side slide holder 12, and the attachment position may be movable in the axial direction.

  Next, the operation will be described. The light incident from the optical fiber 2 is reflected by the mirror 7 and incident on the PD element 32 as indicated by a one-dot chain line C in FIG. Further, the light transmitted through the mirror 7 and reflected by the mirror 8 enters the PD element 42. On the other hand, the light emitted from the LD 52 passes through the mirror 8 and the mirror 7 and enters the optical fiber 2.

  The light reflected by the mirror 7 passes through the optical filter 9, is converged by the lens 35, and enters the PD element 32. Then, it is photoelectrically converted by the PD element 32 and output to the lead pin 33. At this time, the optical filter 9 is disposed on an extension line of the optical axis that extends between the lens 35 and the PD element 32. Therefore, light incident on the PD element 32 always passes through the optical filter 9. As shown in FIGS. 9 and 10, the end surfaces of the package-side rotary holder 17 and the casing-side rotary holder 18 that face each other are part of the spherical surface F, and the first PD package 3 extends along the spherical surface F. Can swing at any angle. Therefore, even if there is a mounting tilt of the mirror 7 or a mounting tilt of the optical fiber 2, it is possible to easily adjust the light so as to enter the optical filter 9 vertically.

  Next, the assembly procedure of the optical module 101 will be described. First, the mirror 7 and the mirror 8 are attached to the mirror holder 6 using an adhesive (not shown) or the like. Next, the optical fiber 2 is attached to the casing 1. The mounting to the casing 1 is not particularly limited as long as the position does not change due to temperature fluctuation or the like after mounting, but in general, the flange portion of the optical fiber 2 is YAG welded to the casing 1. With the optical fiber 2 and the mirrors 7 and 8 fixed to the casing 1, the LD package 5 is attached to the casing 1 using a package side slide holder (hereinafter referred to as a holder) 11 and a casing side slide holder (hereinafter referred to as a holder) 12. . In general, the optical system between the LD 52 using the lens 55 and the fiber ferrule 10 has a magnification of about 4 times. Therefore, the requirement of positional accuracy with respect to the fiber ferrule 10 of the LD package 5 is severe, and the holders 11 and 12 are fixed to each other by YAG welding. First, the LD package 5 and the holder 11 are fixed by projection welding or the like. Next, an appropriate bias current is applied to the LD package 5 to cause the LD 52 to shine, and then the position of the LD package 5 is adjusted so that the level of light emitted from the optical fiber 2 is optimized. In other words, the position is the maximum in the direction perpendicular to the optical axis and the appropriate light output in the direction parallel to the optical axis. At this position, the holders 11 and 12 are penetrated and fixed by YAG welding. Further, the position where the light output from the optical fiber 2 becomes maximum in the direction perpendicular to the optical axis is adjusted, and the space between the holder 12 and the casing 1 is fixed by YAG welding.

  Next, the first PD package 3 is fixed using a package side rotation holder (hereinafter referred to as a holder) 17, a casing side rotation holder (hereinafter referred to as a holder) 18, and a filter cap 16. First, the optical filter 9 is fixed to the filter cap 16 using an adhesive or the like, and the filter cap 16 is placed on the lens cap 34 of the first PD package 3 and fixed by YAG welding. Next, the first PD package 3 is fixed to the casing 1 using the holders 17 and 18. At this time, light is incident from the optical fiber 2 to adjust the position. At this time, the wavelength of the light is a wavelength that greatly depends on the incident angle among the transmission characteristics of the optical filter 9. In the graph shown in FIG. 12, a wavelength near 1561 nm is selected. At this wavelength, the transmission loss varies greatly depending on the incident angle of the optical filter 9. In the adjustment, the angle between the holder 17 and the holder 18 is set to a predetermined angle, and then the position of the first PD package 3 is adjusted so that the light receiving sensitivity of the PD 32 becomes the highest.

  Next, the angle between the holders 17 and 18 is reset to an angle different from the above, and the position of the first PD package 3 is similarly adjusted so that the light receiving sensitivity is maximized. This operation is repeated several times to find the angle and position where the light receiving sensitivity is the highest, that is, the conditions that minimize the transmission loss. Then, after determining the final angle between the rotary holders 17 and 18, it is fixed again by YAG welding at a position where the light receiving sensitivity of the first PD package 3 is maximized. Finally, the second PD package 4 is fixed.

  Since the PD 42 mounted on the second PD package 4 has a large light receiving diameter, unlike the LD package 5 and the first PD package 3, fixing with an adhesive is sufficient. The second PD package 4 receives light from the optical fiber 2 and is fixed with an ultraviolet curing adhesive or the like while adjusting to a position where the light receiving sensitivity is maximized.

  As described above, according to the optical module 101 of the present embodiment, the first PD package 3 supports the optical filter 9 by the filter cap 16 and is spherical with respect to the casing 1 by the holder 17 and the holder 18. Therefore, the incident angle of the light to the optical filter 9 can be easily corrected, and an optimum transmission characteristic can be obtained.

  The optical filter 9 according to the present embodiment is supported from the first PD package 3 by the filter cap 16. However, the optical filter 9 is not limited to the filter cap 16 and is supported from the first PD package 3 by a different shape such as a stay. May be.

  According to the optical module 101 of the present embodiment, the first PD package 3 is rocked along the spherical surface with respect to the casing 1 by the casing-side rotation holder 18 and the package-side rotation holder 17 which are attachment angle variable means. Although supported so as to be movable, the second PD package 4 and the LD package 5 may also be supported so as to be swingable along the spherical surface with respect to the casing 1 by the same mounting angle varying means.

Embodiment 2. FIG.
FIG. 11 is a longitudinal sectional view of an optical module according to a second embodiment of the present invention. In the present embodiment, the number of parts is reduced with respect to that of the first embodiment to reduce the cost. According to the optical module 102 of the present embodiment, in the first PD package 3, the filter lens cap 19 has a bottomed cylindrical shape with a thick bottom portion, and the lens 35 has a through-hole penetrating the thick bottom portion. The optical filter 9 is fixed to the opening end of the through hole. That is, in the present embodiment, the lens 35 and the optical filter 9 are supported by one support member called the filter lens cap 19. The package-side rotation holder 17 is fixed to the outer peripheral surface of the filter lens cap 19 by welding. Other configurations are the same as those of the first embodiment.

  The first PD package 3 of the present embodiment is also a TO-type metal CAN package similar to that of the first embodiment, and the filter lens cap 19 constitutes the outer shell of the TO-type metal CAN package.

  According to the optical module 102 of the present embodiment, since the lens 35 and the optical filter 9 are supported by one support member, the number of parts can be reduced and the cost can be reduced. In the present embodiment, the lens 35 and the optical filter 9 are supported by the filter lens cap 19. However, the lens 35 and the optical filter 9 are not limited to the filter lens cap 19. It may be supported.

  As described above, the optical module according to the present invention is useful for an optical module that mounts a plurality of optical elements and optically couples each optical element to an optical fiber. In particular, each optical element is packaged. Suitable for optical modules.

DESCRIPTION OF SYMBOLS 1 Casing 1a, 1b, 1c, 1d Mounting hole 2 Optical fiber 3 1st photodiode package 4 2nd photodiode package 5 Laser diode package 6 Mirror holder 7, 8 Mirror 9 Optical filter 10 Fiber ferrule 11 Package side slide holder 12 Casing side slide holder 13 Adhesive 16 Filter cap 17 Package side rotating holder (movable holder)
18 Casing side rotating holder (fixed holder)
19 Filter lens cap 31, 41, 51 Stem 32, 42 Photodiode (optical element)
33, 43, 53 Lead pin 34, 44, 54 Lens cap 35, 45, 55 Lens 52 Laser diode (optical element)
101, 102 optical module

Claims (6)

A casing to which an optical fiber is connected;
A plurality of packages mounted on the casing and mounting optical elements, respectively, and an optical system housed in the casing,
The optical element is an optical module that is optically coupled to the optical fiber via the optical system.
An optical filter is provided between at least one of the optical elements and the optical system;
The optical filter is supported from the package,
Between the casing and the package, a fixed holder provided in the casing and a movable holder provided in the package and combined with the fixed holder are disposed, and the fixed holder and the movable holder are opposed to each other. The optical module is characterized in that the end surfaces that face each other are part of a spherical surface, and the movable holder moves along the end surfaces to support the package from the casing so that the angle can be changed. The said package has a lens which condenses light in the immediate vicinity of the said optical element, respectively, The said optical filter and the said lens are supported by one support member. The optical module as described. The optical module according to claim 2, wherein the package is a TO-type metal CAN package, and the support member constitutes an outer shell of the TO-type metal CAN package. The optical module according to any one of claims 1 to 3, wherein the optical system includes a mirror, and the optical filter transmits light reflected by the mirror. The optical module according to any one of claims 1 to 4, wherein the optical element is a photodiode that receives light from the optical fiber via the optical system. The optical module according to any one of claims 1 to 4, wherein the optical element is a laser diode that emits light to the optical fiber via the optical system.

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