JP2014137527A - Optical module and optical module unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress noise due to reflection of light emitted from a light-emitting element.SOLUTION: An optical module includes: a light-emitting element 10 whose light-emitting part is positioned on an optical axis X; a holder 20 made of a material transmitted by light emitted from the light-emitting element 10; and a ferrule 30 which holds an optical fiber 31 so as to expose an end part thereof at a tip end face of the ferrule, and is fitted to the holder 20 so as to align the optical fiber 31 with the optical axis X. In the holder 20, a space 25 which faces a portion containing the exposed end part of the optical fiber 31 at the tip end face of the ferrule 30 is formed, and an interface, crossing the optical axis X, between the material constituting the holder 20 and the space 25 is not a plane orthogonal to the optical axis X.

Description

  The present invention relates to an optical module used for transmitting an optical signal and an optical module unit using the optical module.

  For example, the following Patent Document 1 describes an optical module having a holder in which a space (concave portion) for preventing contact with an optical fiber end surface is formed on the bottom surface of a cylindrical portion (sleeve portion) into which a ferrule is inserted. Yes.

JP 2012-237819 A

  When such a space is formed, there is a problem that light emitted from the light emitting element is reflected at the interface (the bottom surface of the recess) between the material constituting the holder and the air in the space. Such reflected light becomes noise and interferes with light emitted from the light emitting element, or when a light receiving element is provided next to the light emitting element (use an element in which the light emitting element and the light receiving element are packaged). In such a case, the light receiving element receives the signal (crosstalk occurs).

  In view of the above circumstances, the problem to be solved by the present invention is that an optical module including a holder in which a space facing the end of an optical fiber is formed, and an optical module unit using the optical module, is emitted from a light emitting element. It is to suppress noise due to reflection of the emitted light.

  In order to solve the above-described problems, an optical module according to the present invention includes a light-emitting element having a light-emitting portion positioned on the optical axis, a holder made of a material that transmits light emitted from the light-emitting element, and an end portion on the tip surface. Holding an optical fiber so that the optical fiber is exposed, and a ferrule attached to the holder so that the optical fiber follows the optical axis. A space that faces a portion including is formed, and an interface between the material constituting the holder that intersects the optical axis and the space is not a plane orthogonal to the optical axis. The term “plane perpendicular to the optical axis” as used herein does not include a part of the surface that is orthogonal, and is an entirely flat surface that does not have a step or a curved surface and is orthogonal to the optical axis.

  In addition, the interface may have a shape in which a reflected light beam at the interface along the optical axis emitted from the light emitting element becomes a light beam that does not return to the light emitting unit.

  The holder is formed with a lens portion that focuses the divergent light emitted from the light emitting element toward the end of the optical fiber, and the interface is a light beam along the optical axis emitted from the light emitting element. It is preferable that the reflected light beam at the interface be a light beam traveling in a direction not entering the lens unit.

  In order to solve the above-described problems, an optical module unit according to the present invention is an optical module unit in which the optical module and another optical device arranged in parallel with the optical module are provided, and the interface includes light emitted from the light emitting element. The reflected light ray at the interface of the light ray along the axis has a shape that becomes a light ray directed to the side opposite to the other optical device side.

  Further, the interface may be a surface that tapers toward a point intersecting the optical axis and is convex toward the light emitting element.

  In this case, the interface may be a curved surface or a conical surface with a point intersecting the optical axis as a vertex.

  In the optical module according to the present invention, the interface between the material constituting the holder and the space in the holder is not a plane perpendicular to the optical axis. Therefore, the reflected light reflected at the interface in the optical module according to the present invention has fewer components (light rays) toward the light emitting element than in the conventional case where the interface is a plane orthogonal to the optical axis. . That is, it is possible to reduce noise caused by light reflected at the interface.

  In the above case, the noise reduction effect is further enhanced if the interface is formed so that the reflected light beam at the interface of the light beam emitted from the light emitting element is directed to the direction not returning to the light emitting unit. .

  In addition, when a lens unit is provided that focuses the divergent light emitted from the light emitting element toward the end of the optical fiber, the reflected light at the interface of the light along the optical axis emitted from the light emitting element If the shape is a light beam that goes in a direction that does not enter the part, the component (light beam) that is bent by the lens and goes toward the light emitting element is reduced, so that the noise reduction effect is great.

  According to the optical module unit of the present invention, the reflected light beam at the interface of the light beam emitted from the light emitting element along the optical axis becomes a light beam directed to the opposite side of the other optical device side. ) And other optical devices can be reduced.

  Even if the interface is a surface that is tapered toward the point that intersects the optical axis and is convex toward the light emitting element, the component (light beam) that is reflected at the interface and travels toward the light emitting element can be reduced as compared with the conventional case. . In particular, when the interface is a curved surface or a conical surface, there is an advantage that the interface is easily formed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the optical module (what an interface is an inclined surface) concerning one Embodiment of this invention, (a) shows the optical path until the light ray in alignment with the optical axis radiate | emitted from the light emitting element arrives at an interface. (B) shows the optical path of the reflected light beam at the interface of the light beam along the optical axis. It is a schematic diagram of the optical module with which the inclination of the interface was set so that the reflected light ray of the light ray which radiate | emitted from the light emitting element may return to a light emission part, (a) is along the optical axis radiate | emitted from the light emitting element. The optical path until the light beam reaches the interface is shown, and (b) shows the optical path of the reflected light beam at the interface of the light beam along the optical axis. It is a schematic diagram of the optical module in which the inclination of the interface was set so that the reflected ray of the light ray emitted from the light emitting element along the optical axis passes through the outer edge of the lens unit, (a) is the optical axis emitted from the light emitting element (B) shows the optical path of the reflected light beam at the interface of the light beam along the optical axis. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the optical module (what an interface is a curved surface) concerning one Embodiment of this invention, (a) showed the optical path until the light ray in alignment with the optical axis radiate | emitted from the light emitting element arrives at an interface. (B) shows the optical path of the reflected light beam at the interface of the light beam along the optical axis. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the optical module (one whose interface is a cone surface) concerning one Embodiment of this invention, (a) shows the optical path until the light ray in alignment with the optical axis radiate | emitted from the light emitting element arrives at an interface. (B) shows the optical path of the reflected light beam at the interface of the light beam along the optical axis. It is a schematic diagram of the optical module unit concerning one Embodiment of this invention. It is a schematic diagram of the conventional optical module, (a) shows the optical path until the light ray along the optical axis emitted from the light emitting element reaches the interface, and (b) is along the optical axis. The optical path of the reflected light beam at the light beam interface is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Each figure schematically shows a cross section of the optical module 1 or the optical module unit 1u, but hatching is omitted for easy understanding of the figure. An optical module 1 (1 a) according to an embodiment of the present invention shown in FIG. 1 includes a light emitting element 10, a holder 20, and a ferrule 30.

  The light emitting element 10 is a member that emits light constituting a signal to be transmitted. Specifically, it is a photoelectric conversion element that converts a signal to be transmitted from an electric signal to an optical signal and emits it. In the present embodiment, the light emitting element 10 is mounted on a substrate B on which a circuit that generates an electrical signal (transmits a signal to the light emitting element 10) is formed.

  The holder 20 is a member formed of a material that transmits light (laser light that transmits a signal) emitted from the light emitting element 10. The holder 20 has a cylindrical portion 21 formed in a cylindrical shape (this embodiment is a cylindrical shape with a step) and a sleeve portion 22 that is also formed in a cylindrical shape. The cylindrical portion 21 is a portion surrounding the light emitting element 10 mounted on the substrate B. Specifically, the tip of the cylindrical portion 21 is fixed by soldering or the like around the portion of the substrate B where the light emitting element 10 is mounted. A lens portion 23 is formed on the inner bottom surface (upper surface in FIG. 1) of the cylindrical portion 21. The lens portion 23 is a convex lens through which divergent light (laser light having a predetermined divergence angle (divergence angle)) emitted from the light emitting element 10 located inside the cylindrical portion 21 is transmitted. Is refracted so that divergent light entering the laser beam becomes focused light (laser light having a predetermined focusing angle) toward an end of an optical fiber 31 described later. The optical axis X of the lens unit 23 coincides with the optical axis X of the light emitting element 10 (light emitted from the light emitting element 10).

  The sleeve portion 22 is a portion into which the ferrule 30 having the optical fiber 31 fixed therein is inserted. The inner diameter is set to be substantially the same as the outer diameter of the ferrule 30 (set so that a gap is not generated as much as possible) between them. On the inner bottom surface (lower surface in FIG. 1) of the sleeve portion 22, a concave portion 24 that is recessed toward the light emitting element 10 side (lens portion 23 side) is formed. The inner diameter of the recess 24 is smaller than the inner diameter of the sleeve portion 22. Accordingly, there is a step between the recess 24 and the inner wall surface of the sleeve portion 22. When the ferrule 30 is inserted inside the sleeve portion 22, the periphery of the ferrule 30 hits the step (the inner bottom surface of the sleeve portion 22). By inserting the ferrule 30 to the abutting position, the ferrule 30 is positioned with respect to the holder 20. The optical fiber 31 is fixed at the center of the ferrule 30. The axis of the optical fiber 31 fixed to the ferrule 30 positioned with respect to the holder 20 coincides with the optical axis X of the lens portion 23 and the light emitting element 10 (light emitted from the light emitting element 10). That is, the optical fiber 31 is provided along the optical axis X.

  The end of the optical fiber 31 is exposed at the center of the front end surface of the ferrule 30 (the surface abutted against the step). The portion where the optical fiber 31 is exposed faces the space 25 inside the recess 24. More specifically, a portion (a part on the center side) including the exposed end portion of the optical fiber 31 on the tip surface of the ferrule 30 faces the space 25 inside the recess 24. When such a space 25 is formed, the end portion of the optical fiber 31 does not contact the holder 20 when the ferrule 30 is inserted into the sleeve portion 22. That is, damage to the end of the optical fiber 31 is prevented.

  In the optical module 1 a having such a configuration, the divergent light emitted from the light emitting element 10 is converged by the lens unit 23 and enters the optical fiber 31. That is, the optical signal output from the light emitting element 10 is transmitted to a light receiving element (not shown) through the optical fiber 31. At this time, the light focused by the lens unit 23 is an interface 26 (26a) between the holder 20 intersecting the optical axis X and the space 25, that is, “light transmissive material constituting the holder 20” having a different refractive index. It passes through the interface 26a of "air existing in the space 25". Therefore, a part of the emitted light is reflected at the interface 26a. In the present embodiment, the interface 26 (the bottom surface of the recess 24 in another way) intersecting the optical axis X is a plane orthogonal to the optical axis X so that the reflected light is not directed to the light emitting element 10 as much as possible. It is formed not to become. The reason will be described below. In the following description with reference to FIGS. 1 to 3 and 7, the optical axis that is the highest intensity portion of divergent light (laser light having a predetermined divergence angle) emitted from the light emitting element 10. A description will be given with reference to a ray along X (coincided with the optical axis X) and its reflected ray. Also in FIG. 1, a light beam along the optical axis X and a reflected light beam thereof are illustrated.

  In the case of a conventional configuration in which the interface 26z is a plane orthogonal to the optical axis X as in the optical module 1z shown in FIG. 7, when a light beam along the optical axis X is reflected by the interface 26z, the reflected light beam The light beam is directed in the opposite direction by 180 degrees, that is, the light beam traveling toward the light emitting element 10 along the optical axis X. That is, since the light beam along the optical axis X, which is the highest intensity portion, returns straight as it is, noise due to reflected light increases.

  On the other hand, when the interface 26a is an inclined surface inclined with respect to the optical axis X as in the optical module 1a shown in FIG. 1, when the light beam along the optical axis X is reflected by the interface 26a, the reflected light beam Becomes a light beam not directed to the light emitting element 10. Specifically, the larger the tilt angle, the more the reflected light beam goes toward the outside. In other words, the light beam along the optical axis X, which is the highest intensity portion, does not return straight as it is, and the reflection is directed toward the outside, so that the noise caused by the reflected light is smaller than in the past.

  When the holder 20 has the lens portion 23, the reflected light beam at the interface 26 a of the light beam along the optical axis X may be refracted by the lens portion 23 and return to the light emitting portion of the light emitting element 10 as it is. For example, the holder 20 (material refractive index = 1.64, d1 = 2.37 mm, d2 = 3.37 mm, lens part 23; diameter 1.4 mm, thickness 2.6 mm) formed in the shape shown in FIGS. In the case of the optical module 1 using a curvature radius of 0.8 mm, when the inclination angle of the interface 26a (angle difference from the plane perpendicular to the optical axis X) is 0.3 degrees, the reflected light beam of the light beam along the optical axis X is reflected. Is returned as it is to the light emitting part of the light emitting element 10 (when the light emitting part is assumed to be a point) (see FIG. 2). Therefore, if the angle of inclination of the interface 26a exceeds 0.3 degrees so that the reflected light beam at the interface 26a of the light beam along the optical axis X does not return to the light emitting part of the light emitting element 10, the noise reduction effect is enhanced.

  More preferably, the reflected light beam at the interface 26a of the light beam along the optical axis X is set to be a light beam that goes in a direction not entering the lens unit 23. This is because if the setting is made so that the reflected light beam does not enter the lens portion 23, the component (light amount) of light that is bent at the lens portion 23 and travels toward the light emitting element 10 is reduced. When the holder 20 is used, the reflected light of the light beam along the optical axis X becomes a light beam that passes outside the lens portion 23 by setting the inclination angle of the interface 26a to more than 6.5 degrees (see FIG. 3). That is, noise can be further reduced if the inclination angle of the interface 26a exceeds 6.5 degrees.

  Thus, if the interface 26a is an inclined surface that is not a plane orthogonal to the optical axis X, a certain noise reduction effect can be obtained. That is, if the portion of the interface 26a that intersects the optical axis X is not orthogonal, the reflected light beam at the interface 26a of the light beam along the optical axis X included in the divergent light emitted from the light emitting element 10 (the light beam with the highest intensity). Since the light does not travel toward the light emitting element 10 along the optical axis X, a predetermined noise reduction effect can be obtained. If the noise reduction effect is further enhanced, it is preferable to set so that the reflected light beam at the light interface 26 a along the optical axis X does not return to the light emitting portion of the light emitting element 10. More preferably, the reflected light beam at the interface 26a of the light beam along the optical axis X is set to be a light beam that goes in a direction not entering the lens unit 23.

  In the configuration shown in FIG. 1, the interface 26a is an inclined surface having a certain angle, but may be an inclined surface in which only a part is inclined. Even in that case, the light rays reflected by the part of the inclined surfaces are directed to the outside of the holder 20 more than in the case of the conventional configuration (a configuration in which the entire interface 26z is a plane perpendicular to the optical axis X). Since it becomes a light beam, noise can be reduced as compared with the conventional configuration. However, in the case where the interface 26 is an inclined surface in which only a part is inclined as described above, it is preferable that at least a portion intersecting the optical axis X is an inclined surface in order to increase the noise reduction effect.

  On the other hand, even if the interface 26 is tapered toward a point (vertex) intersecting the optical axis X and is convex toward the light emitting element 10 side, a certain noise reduction effect can be obtained. In the case of such a shape, the light beam along the optical axis X included in the divergent light emitted from the light emitting element 10 becomes a light beam that returns straight to the light emitting element 10 as it is reflected by the interface 26, but is emitted from the light emitting element 10. The other light rays (light rays other than the light rays along the optical axis X) included in the diverging light, that is, the light rays gradually spreading as the distance from the optical axis X increases, the light rays go outward greatly when reflected by the tapered interface 26. (See FIGS. 4 and 5). Specifically, the light beam reflected by the interface 26 from the other light beam is a light beam directed outward than when the interface 26 is a plane orthogonal to the optical axis X (conventional configuration). In other words, the light reflected by the interface 26 from the divergent light emitted from the light emitting element 10 becomes divergent light that spreads outward more greatly than in the past. Therefore, the noise reduction effect by the component which goes to the light emitting element 10 less than before is show | played.

  As the shape of such a tapered interface 26, a curved surface 26b having a vertex intersecting with the optical axis X as in the optical module 1b shown in FIG. 4 or a conical surface 26c like the optical module 1c shown in FIG. Can be illustrated. In the case of the curved surface 26b and the conical surface 26c, the shape of the interfaces 26b and 26c can be easily formed with a cutting tool for forming the recess 24 (a cutting tool whose tip shape when rotating is a curved surface or a conical surface). There is an advantage that can be.

  In addition, as in the configuration shown in FIG. 1, when the interface 26a is formed in a shape where the interface 26a and the optical axis X intersect with each other so that they are not orthogonal to each other, the shape of the interface 26a is different from that of the optical module. Considering the position of the optical device M, it is preferable to set as follows. When a system for transmitting and receiving optical signals between a plurality of devices is constructed, both the light emitting element 10 and the light receiving element are provided in one device (an element in which the light emitting element 10 and the light receiving element are packaged together is used). In some cases). When another optical device M such as the light receiving element is provided, the interface 26a in the holder 20 of the optical module 1a having the light emitting element 10 is different from the reflected light at the interface 26a of the light beam along the optical axis X. It sets so that it may become the light beam which goes to the other side of the light receiving element side (optical module side which has a light receiving element) which is the target apparatus M. Note that the “light beam traveling in the opposite direction” here includes all those whose distance from another optical device M increases as the light travels. That is, all of the ray vectors that go away from another optical device are included.

  Specifically, when another optical device M such as a light receiving element is located on the left side of the optical module 1a as shown in FIG. 6, the inclination of the interface 26a at the portion where the interface 26a and the optical axis X intersect is The slope is gradually downward from right to left. On the other hand, when another optical device M is positioned on the right side of the optical module 1a, the inclination of the interface 26a at the portion where the interface 26a intersects the optical axis X gradually increases from left to right. Inclined downward. If the optical module unit 1u composed of the optical module 1a and another optical device M is designed in this way, the reflected light beam at the interface 26a of the light beam along the optical axis X having the highest intensity is separated from the other optical device. Since the light beam travels in a direction away from M, crosstalk (noise with respect to another optical device M) generated between the optical module 1a having the light emitting element 10 and another optical device M such as a light receiving element is reduced. can do.

  According to the optical module 1 according to the present embodiment described above and the optical module unit 1u using the optical module, the following operational effects are achieved.

  In the optical module 1 according to the present embodiment, the interface 26 between the material constituting the holder 20 and the space 25 in the holder 20 is not a plane orthogonal to the optical axis X. Therefore, the reflected light reflected by the interface 26 has fewer components (light rays) toward the light emitting element 10 than in the conventional case where the interface 26 is a plane perpendicular to the optical axis X. That is, it is possible to reduce noise caused by light reflected from the interface 26.

  Further, if the interface 26 is formed so that the reflected light beam at the interface 26 of the light beam emitted from the light emitting element 10 along the optical axis X becomes a light beam that does not return to the light emitting unit, the noise reduction effect is further increased. Rise.

  In addition, in the case where the lens unit 23 that focuses the divergent light emitted from the light emitting element 10 toward the end of the optical fiber 31 is provided, the interface 26 of the light beam along the optical axis X emitted from the light emitting element 10. If the shape of the reflected light beam becomes a light beam that goes in a direction that does not enter the lens unit 23, the component (light beam) that is bent by the lens and travels toward the light emitting element 10 is reduced.

  Further, as in the optical modules 1b and 1c, even if the interfaces 26b and 26c are surfaces that are tapered toward the point where the optical axis X intersects and protrude toward the light emitting element 10, they are reflected by the interfaces 26b and 26c. The component (light beam) toward the light emitting element 10 can be reduced as compared with the conventional case. In particular, when the interface is a curved surface (26b) or a conical surface (26c), there is an advantage that the interface is easily formed.

  According to the optical module unit 1u using the optical module 1a, the reflected light beam at the interface 26z of the light beam along the optical axis X emitted from the light emitting element 10 is a light beam traveling toward the opposite side to the other optical device M side. Therefore, crosstalk between the light emitting element 10 (optical module 1a) and another optical device M can be reduced.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  For example, the shape of the illustrated holder 20 and the specifications of the light emitting element 10 can be changed as appropriate without departing from the scope of the present invention.

  Moreover, although the recessed part 24 formed in the holder 20 demonstrated that it was formed in order to prevent the damage of the optical fiber 31 end part by the end part of the optical fiber 31 and the holder 20 contacting, The purpose of forming the recess 24 is not limited to this. That is, the technical idea of the present invention can be applied as long as the interface 26 between the material constituting the holder 20 and the air exists in the optical path from the light emitting element 10 to the optical fiber 31. Furthermore, the technical idea of the present invention can be applied even when a substance other than air (excluding the material constituting the holder 20) is present in the recess 24. In other words, any configuration may be used as long as the recess 26 formed in the holder 20 forms the interface 26 in which reflection occurs in the optical path from the light emitting element 10 to the optical fiber 31.

DESCRIPTION OF SYMBOLS 1 Optical module 1u Optical module unit 10 Light emitting element 20 Holder 21 Cylindrical part 22 Sleeve part 23 Lens part 24 Recessed part 25 Space 26 Interface 30 Ferrule 31 Optical fiber X Optical axis M Another optical apparatus

Claims (6)

A light emitting element having a light emitting portion located on the optical axis;
A holder made of a material that transmits light emitted from the light emitting element;
Holding the optical fiber so that the end portion is exposed at the distal end surface, and a ferrule attached to the holder so that the optical fiber is along the optical axis;
With
The holder is formed with a space facing a portion including the exposed end portion of the optical fiber on the tip surface of the ferrule,
An optical module, wherein an interface between a material constituting the holder intersecting an optical axis and the space is not a plane orthogonal to the optical axis.   2. The interface according to claim 1, wherein the interface has a shape in which a reflected light beam at the interface along a light axis emitted from the light emitting element becomes a light beam that does not return to the light emitting unit. Optical module. The holder is formed with a lens portion that focuses diverging light emitted from the light emitting element toward an optical fiber end,
2. The interface according to claim 1, wherein the interface has a shape in which a reflected light beam at the interface along the optical axis emitted from the light emitting element becomes a light beam that goes in a direction not entering the lens unit. 2. The optical module according to 2. An optical module unit provided with the optical module according to claim 2 or claim 3 and another optical device aligned therewith,
The optical module unit is characterized in that the interface has a shape in which a light beam reflected by the interface along the optical axis emitted from the light emitting element is a light beam directed to the opposite side of the other optical device side. .   The optical module according to claim 1, wherein the interface is a surface that is tapered toward a point intersecting the optical axis and is convex toward the light emitting element.   6. The optical module according to claim 5, wherein the interface is a curved surface or a conical surface having a vertex at a point intersecting the optical axis.

Images