JP2012208174A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module capable of improving the packaging density of optical collimators and reducing the damage on optical fibers due to the heating temperature in fixing the optical collimators.SOLUTION: The optical module includes optical collimators 102 each having an optical fiber 109, and a housing 103 having, on its surface, optical collimator fixing parts 112 for fixing the optical collimators 102. Each of the optical collimators 102 has an optical lens 104, a ferrule 105 for holding the optical fiber 109, and a fixing sleeve 106 for fixing the optical lens 104 and the ferrule 105. The ferrule 105 has a base end part 105A, a tip part 105B to be fixed to the fixing sleeve 106, and a reduced diameter part 105C with an outer diameter smaller than that of the base end part 105A and that of the tip part 105B. The optical collimator fixing part 112 and the fixing sleeve 106 are fixed to each other at the side of the tip part 105B of the ferrule 105 through a heat curing agent 114.

Description

  The present invention relates to an optical module.

  In an optical module using an optical collimator having an optical fiber, an input / output optical collimator is held in a housing that houses a plurality of optical functional components. Conventionally, the optical collimator is fixed to the housing by using laser welding such as YAG laser or soldering (for example, Patent Document 1).

Japanese Patent Laid-Open No. 08-179176

  In fixing the housing and the optical collimator using a YAG laser, which is generally performed, it is necessary to secure an optical path for irradiating the YAG laser between the housing and the optical collimator. However, when a plurality of optical collimators are arranged close to each other due to high density, it becomes difficult to secure a sufficient optical path for laser irradiation around each optical collimator, and a shaded part appears. End up. As a result, there is a problem that the amount of laser light for fixing is insufficient and cannot be fixed. Further, even if temporarily fixed, the amount of laser light is insufficient, so that sufficient fixing strength is not ensured, leading to a decrease in reliability and a deterioration in characteristics.

In addition, when fixing using solder or the like, the allowable range of the fixing condition is narrow, and measures such as heat dissipation are required. For example, as shown in FIG. 7, in the conventional configuration, the entire axial direction of the ferrule 205 that holds the distal end portion of the optical fiber core wire 101 is soldered in a state where it is in contact with the fixed sleeve 206. For this reason, the heating temperature (about 270 to 280 ° C.) at the time of soldering is transferred to the optical fiber core 101 held in the ferrule 205 to cover the optical fiber core 101 held in the ferrule 205. The layer 108 is damaged such as melting and deformation.
In this way, if the heat dissipation during solder bonding is insufficient, the coating temperature of the optical fiber (optical fiber core wire) is damaged by the heating temperature, and characteristics and reliability are likely to deteriorate. There's a problem. Even when sufficient heat dissipation measures are taken, it is difficult to reduce the number of work steps because it takes time to overheat a desired portion because heat is easily diffused to the surroundings.

  The present invention has been made in view of the above-described problems of the prior art, and can improve the mounting density of the optical collimator and reduce damage to the optical fiber due to the influence of the heating temperature during fixing. One of the objects is to provide an optical module.

  An optical module of the present invention includes an optical collimator having an optical fiber, and a housing provided with an optical collimator fixing portion for fixing the optical collimator on a surface thereof. The optical collimator includes an optical lens and a coating layer. Has a ferrule that holds the tip side of the optical fiber from which a part of the optical fiber is removed, and a fixing sleeve that fixes the optical lens and the ferrule, and the ferrule is partly in the axial direction than other parts. The fixed sleeve of the optical collimator and the optical collimator fixing portion are fixed by a heat curing agent at a location away from the reduced diameter portion and the coating layer of the ferrule. It is characterized by being.

  In addition, the ferrule includes a proximal end portion that holds the portion including the coating layer of the optical fiber, the reduced diameter portion that is axially continuous with the proximal end portion, and the proximal end portion of the reduced diameter portion. And a distal end portion provided on the opposite side in the axial direction, the state where the distal end portion is in contact with the fixed sleeve, and the state where the base end portion and the reduced diameter portion are separated from the fixed sleeve It is good also as a structure fixed with respect to the said fixing sleeve.

  The optical collimator fixing part and the ferrule may be fixed by adhesive or laser irradiation at a location close to the coating layer of the ferrule.

  Further, the casing may be configured such that the thickness in the vicinity of the optical collimator fixing portion is thinner than the thickness of other portions.

  Moreover, it is good also as a structure which forms a groove | channel in the said housing | casing at the circumference | surroundings of the said optical collimator fixing | fixed part.

  Further, the heat curing agent may be a solder.

  Also, the casing side of the optical collimator fixing portion is in communication with the fixing sleeve insertion hole of the collimator fixing portion and for injecting the heat curing agent that fixes the optical collimator fixing portion and the fixing sleeve. It is good also as a structure in which the injection hole is formed.

According to the present invention, a part of the ferrule in the axial direction is thinner than the other part, and the entire axial direction does not contact the fixed sleeve when the ferrule is fixed to the fixed sleeve. .
That is, only the distal end portion of the ferrule is fixed in contact with the fixed sleeve, and the diameter-reduced portion and the base end portion continuous thereto are not in direct contact with the fixed sleeve. As a result, the temperature at the time of solder joining between the fixing sleeve and the collimator fixing portion is transferred to the base end portion through the reduced diameter portion. However, the reduced diameter portion has a small cross-sectional area and has a poor thermal conductivity. It is possible to suppress the temperature rise at the end, and it is possible to prevent deterioration of the characteristics and reliability of the optical module.

  Moreover, since the heat conduction from the heating part to other parts is poor, the temperature of the heating part can be increased efficiently, and as a result, the bonding time is shortened and the productivity is improved.

  As described above, when the optical collimator is mounted on the housing, the fixing by the YAG laser is not necessary, so that the optical collimators can be arranged close to each other, and the mounting density of the optical collimator can be improved. Thereby, the optical module can be reduced in size.

The perspective view which shows the principal part of the optical module which is 1st Embodiment. Sectional drawing which shows the structure of the optical collimator mounted in the housing | casing. Sectional drawing which shows each dimension of an optical fiber core wire and a collimator. (A) is sectional drawing which shows schematic structure of the optical module of 2nd Embodiment, (b) is a top view of (a). The top view which shows the modification of a groove part. The perspective view which shows the whole optical module typically. Sectional drawing which shows the structure of the conventional optical module. The top view which shows the modification of a groove part.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[First Embodiment]
FIG. 1 is a perspective view showing a main part of an optical module according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the optical collimator mounted on the housing.
As shown in FIG. 1, the optical module 100 of the present embodiment includes an optical fiber core wire 101, a plurality of optical collimators 102 that hold the distal end side of the optical fiber core wire 101, and a plurality of optical collimators 102 fixed (mounted). ).

  As shown in FIG. 2, the optical collimator 102 includes an optical lens 104, a ferrule 105 into which the tip of the optical fiber core wire 101 is inserted and held, and a fixed sleeve 106 to which the optical lens 104 is fixed and holds the ferrule 105. And.

  The ferrule 105 has a base end portion 105A, a tip end portion 105B, and a reduced diameter portion 105C provided between the base end portion 105A and the tip end portion 105B. The base end portion 105A, the reduced diameter portion 105C, and The outer diameters of the front end portions 105B are set to different dimensions. In the present embodiment, the reduced diameter portion 105C is formed to have a shape that is reduced in diameter than the outer diameters of the proximal end portion 105A and the distal end portion 105B. Note that the outer diameter of the distal end portion 105B and the proximal end portion 105A may be the same. Examples of the material of the ferrule 105 include kovar and stainless steel.

  An optical fiber insertion hole 107 for inserting the optical fiber 109 is formed in the entire axial direction of the ferrule 105, and a coating layer 108 made of nylon or Hytrel (registered trademark) is placed in the optical fiber insertion hole 107. The distal end side of the optical fiber core wire 101 from which the part has been removed is fixed with an adhesive (not shown) or the like. The rear end side of the optical fiber insertion hole 107 has an inner diameter that is larger than that of the other part, and the boundary part having a different inner diameter in the axial direction (between the first hole 107a and the second hole 107b) toward the rear end side. A tapered portion 107c whose inner diameter gradually increases toward the end is provided. The taper portion 107c is for facilitating insertion of the tip of the optical fiber 109 from the rear end side of the optical fiber insertion hole 107, and prevents bending or damage of the optical fiber tip side.

  Here, the rear end side of the ferrule tubular body 110 is press-fitted into the front end portion 105 </ b> B of the ferrule 105. The ferrule tubular body 110 is fixed in the second optical fiber insertion hole 111 formed on the inner side so as to be coaxial with the optical fiber insertion hole 107 of the ferrule 105, and is inserted into the second optical fiber insertion hole 111. The tip side of the optical fiber 109 from which the coating layer 108 has been removed is inserted and held.

  The ferrule tubular body 110 is provided in a state in which the distal end surface 110 a is slightly protruded from the distal end side of the ferrule 105. The distal end surface 110 a of the ferrule tubular body 110 is an inclined surface formed by being obliquely polished together with the optical fiber 109, and is inclined at a predetermined angle with respect to a surface orthogonal to the axial direction of the optical fiber 109. ing. Thereby, the return loss characteristic at the end face 109a can be improved. An antireflection film may be provided on the entire inclined surface including the end surface 109 a of the optical fiber 109.

  Examples of the material of the ferrule tubular body 110 include ceramic materials such as zirconia, glass, and metal materials such as stainless steel and nickel.

The fixed sleeve 106 has a cylindrical shape, holds the ferrule 105 inside, and fixes the optical lens 104. The fixing sleeve 106 is formed with a ferrule insertion hole 106a, a ferrule holding hole 106b, and an optical lens fixing hole 106c penetrating in the axial direction. In this embodiment, the optical lens fixing hole 106c has a size larger than the inner diameter of the ferrule holding hole 106b in order to facilitate the positioning of the optical lens 104 in the axial direction. It may be substantially the same.
The fixing sleeve 106 is made of a metal material such as stainless steel or an alloy such as kovar.

  The ferrule 105 is fixed to the fixing sleeve 106 by welding, press-fitting, or adhesive with a YAG laser or the like in the ferrule holding hole 106b. The ferrule 105 is joined to the fixed sleeve 106 in a state where adjustment in the axial direction is performed between an end surface 109a of the optical fiber 109 and an optical lens 104 described later.

  In addition, an optical lens 104 made of an aspheric lens or the like that uses light emitted from the tip of the optical fiber 109 as a parallel beam is fixed in the optical lens fixing hole 106c. By fixing in the optical lens fixing hole 106 c, the optical lens 104 is arranged at a predetermined distance from the tip of the optical fiber 109.

  As the optical lens 104, for example, a spherical lens, an aspherical lens, a compound lens including a plurality of lenses, or the like may be used. Furthermore, a mold lens in which an optical lens is mounted on a metal frame can be used. In this case, the optical lens fixing hole 106c is fixed by welding with a laser or the like, thereby enabling more reliable fixing.

  Here, the axial position of the ferrule 105 and the optical lens 104 fixed in the fixing sleeve 106 maximizes the optical coupling efficiency with the other optical collimators 102 facing each other when mounted on the housing 103. To be adjusted. The light passing through the optical lens 104 is not limited to a parallel beam (collimated light), and may be a condensed beam as long as the optical coupling efficiency is maximized.

  As described above, a plurality of optical collimators 102 having the optical fiber 109 are mounted on the housing 103. The housing 103 accommodates a plurality of functional parts inside, and is formed in a box shape as shown in FIG. 6, for example. In this case, a plurality of optical collimators 102 are fixed to the side wall 103b of the housing 103, and collimated light R emitted from each optical collimator 102 is condensed at one point in a lens 122 incident through a mirror 121 installed therein. Is done. The arrangement of the optical collimator 102 and the shape of the housing 103 are not limited to this.

  Here, returning to FIG. An optical collimator fixing portion 112 for fixing the optical collimator 102 is provided on the wall portion 103 </ b> A of the housing 103. The optical collimator fixing portion 112 has a cylindrical shape protruding outward from the surface 103a of the wall portion 103A, and the optical collimator 102 is inserted and held in the inner through hole 113. ing. The through hole 113 is slightly larger than the outer diameter of the optical collimator 102 (the outer diameter of the fixed sleeve 106), and the optical collimator 102 is disposed on the same axis. The optical collimator 102 is fixed to the optical collimator fixing portion 112 via a heat curing agent 114 such as solder disposed in the through hole 113.

An injection hole 115 for injecting the heat curing agent 114 into the through hole 113 is provided on the side surface of the optical collimator fixing portion 112. One or more injection holes 115 may be provided. It is preferable that the heat curing agent 114 is disposed only between the optical collimator 102 and the optical collimator fixing portion 112. For this reason, in this embodiment, the fixing sleeve 106 of the optical collimator 102 has a shape that extends toward the base end portion 105A so as to sufficiently cover the distal end portion 105B of the ferrule 105, and the heat curing agent 114 is fixed to the fixing sleeve 106. It is designed not to enter inside. Further, a ferrule insertion hole 106a having a diameter wider than the outer diameter of the distal end portion 105B of the ferrule 105 provided inside the extending portion 106A of the fixed sleeve 106 is used to reduce the diameter-reduced portion 105C of the ferrule 105 and the fixed sleeve 106. The extended portion 106A is not in contact with the extended portion 106A.
In the present embodiment, solder is used as the heat curing agent 114.

On the other hand, the base end portion 105A side of the ferrule 105 is fixed to the optical collimator fixing portion 112 via an adhesive 116 such as an epoxy resin. The adhesive 116 is placed in the ferrule insertion hole 106a so as to fill the space between the base end portion 105A of the ferrule 105 and the optical collimator fixing portion 112 from the end side opposite to the housing 103 side of the optical collimator fixing portion 112. Injected into.
In addition, you may fix by irradiating with a YAG laser instead of fixing with the adhesive agent 116.

FIG. 3 is a cross-sectional view showing the dimensions of the optical fiber core wire 101 and the ferrule 105.
As shown in FIG. 3, the diameter d1 of the optical fiber core wire 101 including the coating layer 108 is about 1 mm, and the diameter d2 of the optical fiber 109 disposed at the center thereof is 125 μm. As described above, the ferrule 105 that holds the optical fiber core wire 101 includes the three portions having different diameters in the axial direction, the base end portion 105A, the front end portion 105B, and the reduced diameter portion 105C. The diameter D1 of the base end portion 105A is set to 2 mm, the diameter D2 of the tip end portion 105B is set to a little less than 2 mm, and the diameter D3 of the reduced diameter portion 105C is set to 1 mm. Further, the axial length L of the reduced diameter portion 105C is 5 mm, and the diameter d3 of the ferrule tubular body 110 is about 1 mm. In addition, these dimensions are not restricted to this, It can change suitably.

In particular, when the ferrule 105 is made of Kovar or stainless steel and the diameter D3 of the reduced diameter portion 105C is 0.6 to 1.2 mm, the axial length L (mm) of the reduced diameter portion 105C is L: D3 = 6. ˜30: 1, the diameter D2 (mm) of the distal end portion 105B is D2: D3 = 2 to 10: 1, so that the rigidity of the ferrule is ensured and transmitted to the proximal end portion through the reduced diameter portion. Since heat can be suppressed and the temperature rise at the base end can be suppressed, it is possible to prevent deterioration of the characteristics of the optical module and improve reliability.
Further, the effect can be further enhanced by setting the diameter D3 of the reduced diameter portion 105C to 0.8 to 1.2 mm under the above conditions.

  Conventionally, as shown in FIG. 7, the ferrule 205 that holds the distal end portion of the optical fiber core wire 101 is fixed in the fixed sleeve 206 so that the entire axial direction thereof contacts the fixed sleeve 206. Therefore, when such an optical collimator 102 is joined to the optical collimator fixing part 112 by soldering, damage such as melting or deformation of the coating layer 108 of the optical fiber core wire 101 has occurred due to the joining temperature. .

  On the other hand, in the present embodiment shown in FIG. 2, a part of the ferrule 105 in the axial direction is thinner than the other part, and the entire axial direction is fixed to the fixed sleeve 106 when the ferrule 105 is fixed to the fixed sleeve 106. It is the composition which does not touch.

That is, only the distal end portion 105 </ b> B of the ferrule 105 is fixed in contact with the fixed sleeve 106, and the reduced diameter portion 105 </ b> C and the base end portion 105 </ b> A continuous thereto are not in contact with the fixed sleeve 106.
A part of the optical fiber core wire 101 covered with the coating layer 108 is partially inserted into the base end portion 105A. However, since the cross-sectional area of the reduced diameter portion 105C is small and the thermal conductivity is low, the fixed sleeve It is possible to suppress the temperature rise of the base end portion 105A at the time of solder joining between the optical collimator fixing portion 112 and the optical collimator fixing portion 112, and damage to the coating layer 108 can be suppressed. Thereby, it is possible to prevent the deterioration of the characteristics and the reliability of the optical module 100.

Further, since the ferrule 105 is joined only to the distal end portion 105B of the ferrule 105 with respect to the fixing sleeve 106, and the thermal conductivity in the direction of the proximal end portion 105A of the ferrule 105 is poor, the fixing sleeve 106 and the optical collimator fixing portion 112 The heat at the time of soldering is locally held in the vicinity of the solder portion, and the heating efficiency can be increased.
For this reason, the solder which is the heat-hardening agent 114 can be efficiently heat-cured in a short time. Further, since the heat conduction to the base end portion 105A is small and damage to the coating layer 108 can be suppressed, the yield can be improved, and the characteristics and reliability can be improved.

  With the configuration as in this embodiment, when the optical collimator 102 is mounted on the housing 103, fixing by the YAG laser is not required, so that the optical collimators 102 can be arranged close to each other, and the mounting density of the optical collimator 102 can be increased. Can be improved. Thereby, size reduction of the optical module 100 can be achieved.

(Second Embodiment)
Next, the structure of 2nd Embodiment of the optical module of this invention is demonstrated using FIG.
FIG. 4A is a cross-sectional view centering on the schematic configuration of the optical collimator and the housing of the second embodiment, and FIG. 4B is a plan view.
The basic configuration of the optical collimator of this embodiment shown below is substantially the same as that of the previous embodiment, but is partially different in the configuration of the housing 103 portion. Therefore, in the following description, description of common parts is omitted, and in the drawings used for description, the same reference numerals are given to the same components as those in FIGS.

As shown in FIGS. 4A and 4B, in this embodiment, a part of the wall 103A of the housing 103 is thinner than the other parts. Specifically, in the vicinity of the optical collimator fixing portion 112 provided on the surface 103a of the wall 103A of the housing 103, a groove 117 that is recessed from the surface 103a of the wall 103A in the thickness direction is formed. The groove 117 has an annular shape in plan view that surrounds the periphery of the optical collimator fixing portion 112 and has a predetermined width.
Here, the distance between the optical collimator fixing part 112 and the groove part 117 is set within a range in which the strength as the housing 103 is ensured.

  With such a configuration, heat propagation to the housing 103 side during solder bonding can be reduced, so that the heating efficiency can be increased, and the solder that is the heat curing agent 114 can be efficiently used in a short time. Can be cured by heating. Further, since the heat conduction to the base end portion 105A is small and damage to the coating layer 108 can be suppressed, the yield can be improved, and the characteristics and reliability can be improved.

  In the present embodiment, the planar shape of the groove 117 is an annular shape, but the planar shape is not limited to this, and may be another shape such as an ellipse or a rectangle. A plurality of these shapes may be formed concentrically. For example, as shown in FIG. 8, double circular grooves 117a and 117b may be provided concentrically. Further, the planar shape is not continuous, and may be provided intermittently (see FIG. 5).

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

For example, in the previous embodiment, the optical collimator fixing portion 112 is provided with the injection hole 115 for injecting the thermosetting agent into the through hole 113. However, the injection hole 115 is provided. It does not have to be. In this case, with the solder wrapped around the outer peripheral surface of the fixing sleeve 106 holding the ferrule 105, the fixing sleeve 106 is inserted into the through hole 113 of the optical collimator fixing portion 112, and then the solder is heated and melted. You may make it join.
Or you may make it inject | pour solder into the through-hole 113 of the optical collimator fixing | fixed part 112 from the inner side of the housing | casing 103. FIG.

  DESCRIPTION OF SYMBOLS 100 ... Optical module, 102 ... Optical collimator, 103 ... Housing, 103a ... Surface, 104 ... Optical lens, 105 ... Ferrule, 105A ... Base end part, 105B ... Tip part, 105C ... Reduced diameter part, 106 ... Fixed sleeve, DESCRIPTION OF SYMBOLS 109 ... Optical fiber, 112 ... Optical collimator fixing | fixed part, 114 ... Heat-hardening agent, 115 ... Injection hole, 116 ... Adhesive agent, 117 ... Solder

Claims (7)

An optical collimator having an optical fiber;
A housing provided with an optical collimator fixing part for fixing the optical collimator on the surface,
The optical collimator includes an optical lens,
A ferrule holding the tip side of the optical fiber from which the coating layer has been partially removed;
A fixing sleeve for fixing the optical lens and the ferrule;
The ferrule has a reduced diameter part having a smaller outer diameter than the other part in a part in the axial direction,
The fixing sleeve of the optical collimator and the optical collimator fixing portion are
An optical module, wherein the ferrule is fixed by a heat-curing agent at a portion away from the reduced diameter portion and the coating layer. The optical module according to claim 1,
The ferrule includes a proximal end portion that holds a portion including the coating layer of the optical fiber, the reduced diameter portion that is continuous with the proximal end portion in the axial direction, and the proximal end portion of the reduced diameter portion is an axis. A distal end portion provided on the opposite side of the direction, wherein the distal end portion is in contact with the fixed sleeve, and the proximal end portion and the reduced diameter portion are separated from the fixed sleeve. An optical module fixed to a fixed sleeve. The optical module according to claim 1 or 2,
The optical collimator fixing part and the ferrule are:
An optical module, wherein the ferrule is fixed by an adhesive or laser irradiation at a portion close to the reduced diameter portion and the coating layer. The optical module according to any one of claims 1 to 3,
The optical module is characterized in that a thickness of the casing in the vicinity of the optical collimator fixing portion is thinner than the thickness of other portions. The optical module according to claim 4, wherein
The optical module according to claim 1, wherein a groove is formed in an annular shape around the optical collimator fixing portion. The optical module according to any one of claims 1 to 5,
The optical module, wherein the heat curing agent is solder. The optical module according to any one of claims 1 to 6,
Injection for injecting the heat curing agent that communicates with the fixing sleeve insertion hole of the optical collimator fixing portion and fixes the optical collimator fixing portion and the fixing sleeve to the housing side of the optical collimator fixing portion. An optical module in which holes are formed.

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