JP2007298738A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module capable of suppressing an increase in the number of the components and the complexity of the structure. <P>SOLUTION: The optical module 1 has a box package 3, and a cylindrical sleeve portion 5 extending from the front wall 7a of the package 3. This sleeve portion 5 has a lens holder 33 holding a lens 31. The lens holder 33 and the front wall 7a of the package 3 are connected by projection-welding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical module having a box-shaped main body.

Conventionally, as such an optical module, an optical module including a butterfly package described in Patent Document 1 below is known. As shown in FIG. 13, in the optical module 101 described in Patent Document 1, the lead pins 105 extend from the left and right side walls of the box-shaped package 103, and the front side wall 107 where the lead pins do not extend has an optical adjustment. A window 109 to which a core member, a lens, an isolator, etc. (all not shown) are connected is formed. An optical device such as an LD (laser diode) element 111 is mounted inside the package 103. In addition to the semiconductor element such as the LD element 111, a thermoelectric conversion element 113 is mounted inside the package 103. The light emitted from the LD element 111 passes through the window 109 and reaches the optical alignment member, and is transmitted to the optical fiber (not illustrated) through a sleeve (not illustrated) attached to the tip of the optical alignment member.
JP 2001-60635 A JP 2001-156194 A JP-A-8-316503

  However, in such an optical module 101, when it is necessary to hermetically seal the package, a light transmitting member such as a sapphire plate is used so that light can be transmitted through the side surface of the package while keeping the hermeticity of the package. It is necessary to assemble to the window 109. Further, in the case where such a light transmitting member is assembled, if an optical fiber and the LD element 111 are optically optimally coupled, they are installed between the LD element 111 and the light transmitting member in the package 103. It is necessary to provide two lenses, a first lens and a second lens installed outside the package 103 and between the light transmission member and the optical fiber. As a result, the number of parts of the optical module 101 is increased and the structure is complicated, leading to an increase in the cost of the optical module 101.

  Accordingly, an object of the present invention is to provide an optical module that can suppress an increase in the number of parts and a complicated structure.

  An optical module according to the present invention includes a box-shaped main body portion and a cylindrical sleeve portion extending from one side wall of the main body portion, and the sleeve portion includes a lens holder that holds a lens, and the lens holder And one side wall of the main body are connected by resistance welding.

  In this optical module, the sleeve portion extending from one side wall of the box-shaped main body portion has a lens holder that holds the lens, and this lens holder is resistance-welded to one side wall of the main body portion. With this configuration, even when airtight sealing inside the main body is necessary, the inside of the main body can be hermetically sealed by the lens of the lens holder. Therefore, it is not necessary to separately provide a light transmitting member or the like for hermetically sealing the inside of the main body while transmitting light between the inside and the outside of the main body, and an increase in the number of parts and a complicated structure can be suppressed. Further, since such a light transmitting member is unnecessary, the lens held by the lens holder can be disposed at an appropriate position, and an appropriate optical coupling between the inside and outside of the main body can be achieved. As a result, it is possible to suppress an increase in the number of lenses due to optical coupling, and it is possible to further suppress a complicated structure.

  Moreover, it is preferable that the groove | channel extended in parallel with one side wall is provided in each of the two side walls which pinch | interpose one side wall of a main-body part. Providing such a groove makes it easier to grip the main body with the welding electrode when resistance welding the main body and the lens holder. Therefore, the main body and the lens holder can be resistance-welded while appropriately pressing and pressing the main body and the lens holder.

  The sleeve portion may further include a sleeve assembly connected to the tip of the lens holder, and the lens holder and the sleeve assembly may be joined by YAG welding. In this case, since the lens holder and the sleeve assembly can be quickly joined by YAG welding, workability can be improved. Further, the inside of the main body may be hermetically sealed with a lens.

  According to the present invention, an increase in the number of parts and a complicated structure can be suppressed.

  Hereinafter, a preferred embodiment of an optical module according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, the light emitting module (optical module) 1 extends forward from a box-shaped package (main body portion) 3 having a substantially rectangular parallelepiped shape and a front side wall (one side surface) 7 a of the package 3. A cylindrical sleeve portion 5 is used. The package 3 includes a metal base 7, and the base 7 includes the front side wall 7 a formed by raising one side of the front. Further, the package 3 includes an upper lid 8 that closes an upper portion of the base 7. Here, the upper direction in the state of FIG. 1 is the Y direction, the direction in which the sleeve portion 5 extends is the Z direction, and the direction orthogonal to both the Y direction and the Z direction is the X direction. Use.

  In the package 3, a multilayer ceramic substrate 11 is arranged in the middle on the side of the rear side wall 9 facing the front side wall 7 a, and a plurality of wiring ceramic surfaces 11 projecting rearward from the rear side wall 9 are arranged in a plurality of lines. Lead pin 13 extends rearward. The light emitting module 1 has a configuration in which the lead pins extend only from the rear side wall 9 side, but a ceramic substrate is arranged on the three walls of the rear side wall 9 and the side walls 15 and 15 orthogonal to the rear side wall 9. A form in which the lead pin extends from each of the three walls is also assumed. In this case, attention is paid to the positional relationship between the lead pins extending from the side walls 15 and 15 and the electrodes 39 so as not to touch the package-side electrode 39 (see FIG. 8) for projection welding during projection welding described later. Must. This is because if the lead pin touches the electrode during projection welding and a large current flows, the lead pin may be welded.

  On the front side in the package 3, a Peltier element 17 is mounted on the base 7, and on the upper plate of the Peltier element 17, a heat sink 18 in which a wiring path is formed is mounted. Further, an LD element 19 and a thermistor 21 are mounted on the heat sink 18. On the rear side of the package 3, a PD (photodiode) 27 that detects the back light of the LD element 19 is mounted on the upper surface of the multilayer ceramic substrate 11 via the chip carrier 23. A driver IC for driving the LD element 19 may be mounted between the PD 27 and the LD element 19.

  The cylindrical sleeve portion 5 extending forward from the front side wall 7 a of the package 3 includes a lens holder 33 that holds the lens 31 and a sleeve assembly 38 that is connected to the front cylindrical portion 33 a at the tip of the lens holder 33. ing. The sleeve assembly 38 includes a joint sleeve 40 fitted on the outer periphery of the front cylinder portion 33 a and a sleeve 41 connected to the front of the joint sleeve 40. Further, the sleeve 41 includes a bush 41a, an inner sleeve 41b, and an outer sleeve 41c, and has a function of holding an optical fiber ferrule 47 inserted from the front. A stub 45 that holds the coupling fiber 43 at the center is held at the inner rear end of the inner sleeve 41b.

  The optical fiber ferrule 47 holding the optical fiber 49 coupled to the light emitting module 1 is inserted from the front of the inner sleeve 41b and abuts against the stub 45. The optical fiber 49 held at the center of the ferrule 47 and the coupling fiber 43 at the center of the stub 45 are in physical contact (Physical Contact). With such a configuration, the light emitted from the LD element 19 is collected by the lens 31 at the rear end of the coupling fiber 43, transmitted to the optical fiber 49 through the coupling fiber 43, and propagated through the optical fiber 49. To do.

  Then, the assembly process of this light emitting module 1 is demonstrated. First, as shown in FIG. 3, the Peltier device 17, the heat sink 18, the LD device 19, the chip carrier 23, the photodiode 27, and the thermistor 21 are fixed inside the package 3, and wire bonding is performed on necessary portions. The base 7 of the package 3 is mainly made of Kovar, and an opening 7b is formed in the front side wall 7a of the base 7. The multilayer ceramic substrate 11 on which the chip carrier 23 is mounted and the lead pin 13 and the LD element 19 are connected is formed in advance as a part of the side wall of the package 3.

  Next, as shown in FIG. 4, the rear portion of the lens holder 33 that holds the lens 31 is inserted into the opening 7 b of the front side wall 7 a of the base 7. The lens 31 and the LD element are slid by sliding the rear surface 3c of the flange 33b of the lens holder 33 and the front surface of the front side wall 7a while causing the LD element 19 to emit light or observing the light emitting end face of the LD element 19. The lens holder 33 is fixed to the front side wall 7a of the base 7 by adjusting the positional relationship with the 19 in the XY plane and performing projection welding (resistance welding) described later.

  Here, conventionally, it is not common to use such resistance welding for a box-type package such as the package 3. This is because it is necessary to specialize the electrodes of the welding apparatus in order to use resistance welding. Therefore, for a box-shaped package provided with a window, conventionally, a first lens is mounted inside the package and a second lens is mounted outside the package to optically couple the LD element and the coupling fiber. It was. On the other hand, in the light emitting module 1, since the lens holder 33 is fixed to the package 3 by projection welding as described above, the hermetic sealing in the package 3 is performed by the lens 31 that also serves as a window material. Done. Then, the inside of the package 3 is hermetically sealed by attaching the upper lid 8 to the base 7 with a seam seal (parallel sealer).

  Subsequently, referring again to FIG. 2, the joint sleeve 40 as the alignment member is slid in the Z direction (optical axis direction) with respect to the lens holder 33, and the front end surface 40 a of the joint sleeve 40 and the sleeve 41 are slid. The XYZ position of the sleeve 41 is adjusted so that the light output from the optical fiber 49 inserted into the sleeve 41 is optimized while sliding the rear end surface 41d of the bush 41a in the XY direction. When the optimum position is reached, the joint B between the lens holder 33 and the joint sleeve 40 is fixed by YAG welding, and the joint C between the bush 41a and the joint sleeve 40 is fixed by YAG welding. Since joints B and C can be quickly joined by YAG welding, workability can be improved. Moreover, according to YAG welding, since the heat | fever added to components is small compared with the joining using a thermosetting adhesive agent, the shift | offset | difference of the alignment by the thermal expansion of components can be suppressed. The light emitting module 1 is completed as described above.

  Hereinafter, the projection welding of the lens holder 33 and the package 3 described above will be described in more detail with reference to FIGS.

  In projection welding, a protrusion with a triangular cross-section (projection part) is made in a part of the part to be welded, and the parts to be welded are brought into contact with each other in a narrow area at the tip of the protrusion, and the narrow contact point is formed. In this method, pressure is applied while instantaneously supplying a large current, and the protrusion is melted to fix the two parts. As described above, by providing the protrusion having a triangular cross section, the contact area between the parts before welding is limited, so that the current density of the flowing current can be increased. In an optical component application such as the light emitting module 1, a current of 2, 3 to 10 kA is normally applied.

  As shown in FIGS. 5 to 7, in the light emitting module 1, the front surface 3 a of the package 3 and the rear surface 33 c of the flange 33 b of the lens holder 33 are projection welded. On the rear surface 33c of the lens holder 33, an annular protrusion 33d having a triangular cross section is formed in advance. Therefore, when the rear part of the lens holder 33 is inserted into the opening 7b of the package 3, the lens holder 33 and the package 3 come into contact with each other at the tip of the protrusion 33d. In such a state, the package 3 and the lens holder 33 are set in the resistance welder 36, and the lens holder 33 and the package 3 are pressed by pressing the lens holder side electrode 37 and the package side electrode 39. A large current is passed between the lens holder side electrode 37 and the package side electrode 39. Since this current flows through a narrow range at the tip of the projection 33d, the projection 33d is melted by this current, and the rear surface 33c and the front surface 3a are welded.

  In such projection welding, in order to strongly press the parts to be welded, it is necessary to pressurize the parts with a welding electrode. For this reason, as shown in FIG. 8, when the lens holder 125 is joined to the box-shaped package 123 of the light emitting module 121, a flange 123b is provided on the package front wall 123a having a through hole, and the front surface of the flange 123b. It is also conceivable that the lens holder 125 is projection welded. In this way, by causing the neck portion 123c between the flange 123b and the package front wall 123a to be hooked on the package-side welding electrode, it is possible to absorb the stress due to the pressurization of the welding electrode. A structure capable of withstanding pressure is obtained.

  However, such a structure of the light emitting module 121, as is apparent at a glance, adopts a special configuration for the package 123, and cost merit is lost. Furthermore, the distance from the LD element 127 mounted in the package 123 to the lens 129 has to be set long, which also disadvantages optically.

  Referring to FIG. 7 again, in the projection welding, the package side electrode 39 is used so that a large current at the time of welding does not flow to a portion unrelated to the welding and damages the package 3 and the components mounted therein. It is preferable that the contact between the package 3 and the package 3 is as close to the welded portion A as possible. By doing so, the large current flowing from the lens holder side electrode 37 does not go to the inside of the package 3, but immediately flows through the welded part A and flows into the package side electrode 39. This is because damage and the like can be suppressed. Note that the current during welding may flow in the direction from the package side electrode 39 to the lens holder side electrode 37.

  Therefore, in the light emitting module 1, as shown in FIGS. 7 and 9, the pair of side walls 15 and 15 on both sides of the package 3 has a pair of slits (grooves) 15a and 15a extending in the Y direction parallel to the front side wall 7a. Is provided. The package side electrode 39 is provided with a pair of gripping portions 39a for gripping the package 3 from both sides. The gripping portions 39a and 39a are inserted into the slits 15a and 15a so that the package 3 is mounted on the package side electrode. 39 is fixed. Thus, since the light emitting module 1 has the slit 15a provided behind the welded portion A of the package 3, the pressure applied in the Z direction by the electrodes 37 and 39 is reliably received during projection welding. It becomes possible. As a result, it is possible to perform welding with higher reliability, and it is difficult for the light emitting module 1 to be poorly sealed.

  Further, with such a configuration, the contact between the package side electrode 39 and the package 3 is close to the welded portion A, so that a large current flowing from the lens holder side electrode 37 does not go to the inside of the package 3, Immediately after passing through the welded part A, it flows into the gripping part 39 a of the package side electrode 39. As a result, it is possible to suppress a large current at the time of welding from flowing to a portion not related to welding, and it is possible to suppress damage to the package 3 and components mounted therein. In addition, since a special configuration such as that of the light emitting module 121 described above is not necessary, the cost is hardly hindered.

  In general, as an optical module assembled using projection welding, a so-called coaxial type optical module as shown in FIG. 10 can be cited. In the coaxial type optical module 141, the welded portion 143, the optical device 145, and the sleeve 147 (or coupling fiber) are arranged in this order along the optical axis. In contrast, in the light emitting module 1 described above, the LD element 19, the welded portion A, and the sleeve 41 (or coupling fiber) are arranged in this order along the optical axis (see FIG. 2). The optical module 141 is a welded portion. The positional relationship with the sleeve (or coupling fiber) is reversed. The light emitting module 1 is also different from the optical module 141 in that the lens 31 is mounted in the immediate vicinity of the welded part A.

  For this reason, in the light emitting module 1, there are parts such as the lens 31 in the immediate vicinity of the portion through which a large current passes during projection welding, so that such a part is not damaged by the large current. Special attention must be paid to the shape of the welding electrode. Therefore, in the resistance welding machine 36 used for the projection welding of the light emitting module 1 described above, as described above, the breakage of components such as the lens 31 is suppressed by adopting a special shape especially for the package side electrode 39. ing.

  FIG. 11 shows an optical module 151 as an example of a conventional butterfly package module. In this optical module 151, a light transmission plate 157 made of optical glass or sapphire plate is attached to a light transmission portion 155 provided on the front surface of the package 153 in order to transmit light and ensure airtightness inside the package 153. There was a need. The cost ratio of the light transmission plate 157 is one factor that hinders cost reduction of this type of butterfly package module. In the case where a sapphire plate that is superior in hardness to optical glass is employed as the light transmission plate 157, the cost reduction is particularly hindered.

  Further, when such a light transmitting plate 157 exists, in order to optically optimally couple the coupling fiber and the LD element, a two-lens system configuration in which lenses are respectively provided inside and outside the package 153 must be employed. I don't get it. Therefore, in this case, the number of parts of the optical module is increased and the structure is complicated, leading to further cost increase of the package. When the above configuration is adopted, the light cross section of the light transmitting portion 155 must be relatively large and the area of the light transmitting plate 157 must be widened. Such a limitation is a bottleneck in cost reduction of the optical module 151 because sapphire suitable as a material for the light transmission plate 157 is expensive and there is little room for reducing the area of the light transmission plate 157. It was.

  On the other hand, in the light emitting module 1 (see FIG. 2), the lens holder 33 to which the lens 31 is attached is joined to the front side wall 7a so as to seal the inside of the package 3 by resistance welding. The inside of the package 3 can be hermetically sealed by the lens 31. Therefore, it is not necessary to separately provide a light transmission plate 157 as described above, and an increase in the number of parts and a complicated structure can be suppressed. Further, since such a light transmission plate 157 is unnecessary, the lens 31 can be disposed at a position close to the opening 7 b of the package 3, and an appropriate optical coupling between the LD element 19 and the coupling fiber 43 can be achieved with only one lens. Can be achieved. As a result, even when the inside of the package 3 is hermetically sealed, it is not necessary to increase the number of lenses for optical coupling, and the structure can be further prevented from becoming complicated.

  Further, in a module having a butterfly type package such as the optical module 101 (see FIG. 13), the LD 111 is first mounted on the package 103 to align the LD element 111 and the optical fiber (or an optical alignment member including a sleeve). Then, a special jig is prepared, and the alignment member is overlaid on the window 109 from above with the package 103 placed vertically with the window 109 facing upward. Then, the light emitted from the fiber attached to the tip of the alignment member is monitored while actually causing the LD element 111 to emit light. And after aligning, it is common to fix each part in the aligning member and the aligning member and the window 109 by YAG welding.

  However, in such an optical module 101, the LD 111 needs to be mounted (usually soldered) in accordance with the position of the lens, so that the relative positional relationship between the lens and the LD 111 tends to vary. In particular, in the direction orthogonal to the front side wall 107, the dimensional tolerance of each component cannot be absorbed, and thus the variation tends to increase. As a result, when the optical fiber and the LD 111 are optically optimally coupled, the positional relationship of the optical fiber with respect to the lens varies. That is, the positional relationship of the optical fiber with respect to the package 103 is likely to vary.

  In particular, in recent butterfly type packages, instead of using a lens holding block having an L-shaped cross section in the package, a flat bench is mounted on the Peltier in the package in order to cool the LD element efficiently. The form which mounts a lens on a flat bench is adopted. In such a form, the height of the center (optical axis center) of the lens from the bottom surface inside the package is almost fixed. This variation in height may not be absorbed even by a two-lens system module including a first lens installed in a package and a second lens installed outside the package.

  In contrast, in the light emitting module 1 (see FIG. 2), as described above, after the LD element 19 is mounted in the package 3, the position of the lens 31 is adjusted and fixed in accordance with the LD element 19. Can do. Accordingly, even when a light transmission plate such as the light transmission plate 157 is used, it is not necessary to consider a margin of positional deviation from the LD element 19, and the area of the light transmission plate can be reduced, thereby reducing the cost. Is possible. In addition, since the lens 31 is fixed in alignment with the LD element 19, the accuracy of the positional relationship between the LD element 19 and the lens 31 can be increased, and the lens 31 that is severe with respect to the positional deviation is employed. It becomes possible. As a result, the above-described light transmission plate becomes unnecessary, and the cost can be reduced.

  Moreover, since the light emitting module 1 has a structure in which the lens 31 can be positioned and fixed with respect to the LD element 19, the positional variation between the LD element 19 and the lens 31 is reduced. For this reason, variation in optical coupling efficiency between the LD element 19 and the coupling fiber 43 is reduced. Furthermore, the positional variation of the coupling fiber 43 with respect to the lens 31 is reduced, and the positional variation between the coupling fiber 43 and the package 3 can be reduced.

  Further, in a general coaxial type optical module such as the optical module 141 (see FIG. 10), the space hermetically sealed is limited to a very narrow space inside the CAP 149. Therefore, it is difficult to put many parts such as Peltier elements in the module. However, the light emitting module 1 having the box-shaped package 3 has a larger component mounting area than the coaxial type, and the components can be mounted in the package 3 relatively easily.

  FIG. 12 shows an optical module 171 in which the connection / wiring of the LD element 19 in the light emitting module 1 is changed to another form. In this optical module 171, the multilayer ceramic substrate 173 has an L shape in plan view, and is disposed on the entire surface inside the package 3. A Peltier element 175 and an LD submount 177 are provided on the base at a position where the multilayer ceramic substrate 173 is cut out. The signal wiring for driving the LD element 19 is connected by wiring between the multilayer ceramic substrate 173 and the LD submount 177 in the connection portion E on the side of the LD element 19. With such a configuration, as a signal wiring for driving the LD element 19, the impedance-matched multilayer ceramic substrate 173 wiring is routed as close as possible to the LD element 19. Therefore, the wiring length of the signal wiring on the LD submount 177 can be shortened, and impedance matching of the wiring on the LD submount 177 is facilitated.

It is a partially broken perspective view which shows the light emitting module which is one Embodiment of the optical module which concerns on this invention. It is another partially broken perspective view which shows the light emitting module of FIG. It is a partially broken perspective view which shows the package of the light emitting module of FIG. It is a partially broken perspective view which shows the package and lens holder of the light emitting module of FIG. It is a perspective view which shows the resistance welding machine of the state which set the package and the lens holder. It is a vertical perspective view which shows the resistance welder in FIG. It is a longitudinal cross-sectional view which shows the resistance welder in FIG. It is a partially broken perspective view which shows another optical module. It is a perspective view which shows the light emitting module of FIG. It is a partially broken perspective view which shows another optical module. It is a partially broken perspective view which shows another optical module. It is a top view which shows another optical module. It is a perspective view which shows the conventional optical module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light emitting module (optical module), 3 ... Package (main part), 5 ... Sleeve part, 7a ... Front side wall (one side wall), 15 ... Side wall, 15a ... Slit (groove), 31 ... Lens, 33 ... Lens holder 38 ... Sleeve assembly.

Claims (4)

A box-shaped main body, and a cylindrical sleeve extending from one side wall of the main body,
The said sleeve part has a lens holder holding a lens, The said lens holder and the said one side wall of the said main-body part are connected by resistance welding, The optical module characterized by the above-mentioned.   The optical module according to claim 1, wherein a groove extending in parallel with the one side wall is provided on each of the two side walls sandwiching the one side wall of the main body. The sleeve portion further includes a sleeve assembly coupled to a tip of the lens holder;
The optical module according to claim 1, wherein the lens holder and the sleeve assembly are joined by YAG welding.   The optical module according to claim 1, wherein the inside of the main body is hermetically sealed by the lens.

Images