JP2001242351A - Device holder type optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module that solves shortcomings incident to the structure for fixedly fitting an SC ferrule to a device holder. SOLUTION: An optical device 21 is stored in a hollow part 22a for loading an optical device in a device holder 22 and fixed with adhesive. An optical fiber 33 is inserted into the special ferrule 25 of a structure for which a cylindrical body (e.g. zirconia ferrule) 27 is force-fitted in a metallic tube (e.g. stainless steel tube) and fixed with adhesive; and then, after grinding the end face 25a of this optical fiber-attached special ferrule 25, it is stored in the hollow part 22b for loading a ferrule in the device holder 22 and fixed with adhesive. One end of the optical fiber 33 is fastened to an MT ferrule as a connector of an optical transceiver. By providing a groove for collecting the adhesive, degrading of coupling characteristics can be prevented which is caused by the flowed-in adhesive for fixing the optical fibers or optical devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device holder type optical module installed in an optical transceiver used for communication of a computer or related equipment using an optical fiber.

[0002]

2. Description of the Related Art Conventionally, as an optical module to be installed in an optical transceiver, a CAN type (metal seal type) optical element (light receiving element or light emitting element) is housed in an optical element mounting hollow portion of a device holder and an adhesive. A device holder type optical module having a structure fixed by the above is used. FIG. 7 shows an example of a device holder type optical module 1 of this type. An optical element (light receiving element or light emitting element) 3 is accommodated in an optical element mounting hollow portion 2a of a device holder 2 and fixed with an adhesive. ing. When the SC connector 5 at the tip of the optical fiber cord 4 connected to the optical transceiver in which the optical module 1 is installed is fitted, the SC ferrule 5
a is inserted into the guide hole 2b of the device holder 2, and the optical axis is automatically adjusted. That is, the optical axis of the optical fiber 6 in the SC ferrule 5a coincides with the center of the light receiving unit or the light emitting unit of the optical element 3. As shown in FIG. 8, two optical modules 1 and 1 ′ on the light receiving side and the light emitting side are installed in the optical transceiver 7 side by side, and a double SC connector 5 is fitted to the optical transceiver 7. At this time, the optical axes on both the light receiving side and the light emitting side are simultaneously aligned. Also, S
The C connector is a single-core optical connector in which an optical fiber is inserted into a precision-processed zirconia cylindrical ferrule (5a), fixed with an adhesive, and the end face is polished.

As shown in FIG. 9, when a two-core MT ferrule 11 is installed as a connector part of an optical transceiver 10, the other end of an optical fiber 12 having one end fixed to the two-core MT ferrule 11. May be directly connected to the device holder type optical module 14 in some cases. The MT ferrule is a ferrule of an optical connector of a pin fitting position alignment method, and has a structure of JI
This corresponds to a ferrule of an F12 type multi-core optical fiber connector of S standard C5981. This optical module 1
4 is an optical element mounting hollow portion 15a of the device holder 15.
The optical element 16 is accommodated therein, fixed with an adhesive, and the tip of the optical fiber 12 to be coupled via the lens portion 17 is accommodated in an alignment groove provided in the fiber holding portion 15b of the device holder 15, and the UV An adhesive of a resin or a thermosetting resin is applied and pressed and fixed by a separate pressing plate 15c.
Reference numeral 18 denotes a substrate, and 19 denotes a receptacle. This optical transceiver 10 connects an MT-RJ connector, and the MT-RJ connector is fitted to the receptacle 19. Note that the MT-RJ connector is an optical connector having a structure in which the above-described pin ferrule type MT ferrule is accommodated in a plug housing (that is, an optical RJ connector having an MT ferrule therein). When this is fitted into the receptacle 19 on the connection partner side, the MT ferrule on the MT-RJ connector side and the MT ferrule 11 on the partner side are connected in a state where they are aligned by pin fitting.

[0004]

The conventional optical module 1 shown in FIG. 7 has the following disadvantages. When the SC connector 5 is connected and disconnected, the device holder 2
And the SC ferrule 5a moves, and the optical axis is slightly shifted each time, and the light coupling characteristics are not stable. For the same reason as described above, if the SC ferrule 5a is eccentric, the change in characteristics due to the insertion and removal of the SC connector 5 becomes very large, so that the SC ferrule 5a and the guide portion 2b of the device holder 2 are processed with extremely high precision. Required and costly. Since the SC ferrule 5a has a long overall length of 8 mm, the device holder 2 inevitably also has a long overall length, which makes it difficult to miniaturize the optical transceiver.

The optical module 14 shown in FIG. 9 does not use a ferrule as compared with the optical module 1 shown in FIG. Further, after the optical fiber 12 is bonded and fixed to the device holder 15, the optical element 16 is actively aligned, and then the optical element 3 is bonded and fixed, so that the coupling characteristics between the optical fiber 12 and the optical element 3 are stabilized. There is. However, there are the following disadvantages. Since the ferrule is not used, the end face of the optical fiber 12 is cut off, so that the performance may be deteriorated due to irregular reflection of light or the like. Since the space between the optical fiber 12 and the device holder 15 (the lower surface of the holding plate 15c) and the space between the CAN-type optical element 16 and the device holder 15 (the outer peripheral surface of the optical element 3) are fixed with an adhesive, If this adhesive flows into the end face of the optical fiber 12 or the lens 17, the coupling characteristics are deteriorated, and at the worst, optical coupling cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional drawbacks, and it is possible to prevent an optical axis shift when an optical connector is inserted and removed, to stabilize optical coupling characteristics, and to process components with high precision. Costs can be reduced without the need for
The size of the device holder can be reduced, the performance can be prevented from being deteriorated due to the irregular reflection of light, and the adhesive for fixing the components flows into the end face of the optical fiber or the like, and the optical coupling cannot be performed. An object of the present invention is to provide a device holder type optical module free from fear.

[0007]

According to the present invention, an optical element is accommodated in a hollow part for mounting an optical element of a device holder and fixed with an adhesive, and an MT as an optical connector part of an optical transceiver is provided. A device holder type optical module in which the other end of an optical fiber having one end fixed to a ferrule is connected, wherein the other end of the optical fiber has a structure in which a cylindrical body is fitted in a metal tube. And the end face of the special ferrule with an optical fiber is polished, and then housed and fixed in the ferrule mounting hollow portion of the device holder. Note that the MT ferrule refers to a ferrule for an optical connector of a pin fitting position alignment method.

According to a second aspect of the present invention, a groove for storing an adhesive is formed in a peripheral portion of a rear end wall of the optical element mounting hollow portion of the device holder according to the first aspect.

According to a third aspect of the present invention, a groove for storing an adhesive is formed in a peripheral edge portion of a rear end wall of the hollow portion for mounting a ferrule of the device holder according to the first aspect.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS. FIG. 1 is a sectional view of a device holder type optical module 20 according to an embodiment of the present invention.
3 is a cross-sectional view of the portion excluding the optical element in FIG. 1, FIG. 3 is a diagram showing only the device holder in FIG. 1, (a) is a front view, (b) is a left side view, and (c) is a right side. FIG.
The illustrated optical module 20 is a light receiving side optical module, in which a CAN type (metal seal type) light receiving element 21 is housed in an optical element mounting hollow portion 22 a of a device holder 22 and fixed with an adhesive 23. A special ferrule 25 is inserted into the ferrule mounting hollow portion 22b formed on the side, and is fixed with an adhesive.

The special ferrule 25 has a fiber hole 2
An optical fiber in which one end is fixed to a MT ferrule 32 (FIGS. 4 and 5) described later, in which a ferrule 27 made of zirconia, which is a cylindrical body (that is, a cylindrical body) having 7a, is press-fitted and fixed to a stainless steel tube 26. 33 is connected to the other end. After polishing the end face 25a of the special ferrule 25 with the optical fiber, the device holder 22 is polished.
And is fixed with an adhesive 34. Further, a groove 22c for storing an adhesive is formed in a ring shape at a peripheral portion of a rear end wall of the optical element mounting hollow portion 22a, and the adhesive pool is formed at a peripheral edge of a rear end wall of the ferrule mounting hollow portion 22b. The groove 22d is formed in a ring shape. Reference numeral 35 denotes a lens, and 36 denotes a lead of the light receiving element 21. The notch 22 is formed in the device holder 22 so that an adhesive 23 for bonding the light receiving element 21 can be easily applied.
e. The cutout portion 22f on the outer periphery of the device holder 22 is a portion into which a holding portion of a jig for fixing the device holder 22 to the assembling apparatus when assembling the optical module 20 is inserted. 22h is a light passage hole between the ferrule mounting hollow portion 22b and the optical element mounting hollow portion 22a.

The above-mentioned device holder type optical module 2
The assembly of 0 is performed as follows. Optical fiber 33
Of the end of (1) (cut off the coating) and cut the end surface. The leading end of the optical fiber 33 is inserted into the fiber hole 27a of the special ferrule 25 and fixed with an adhesive.
The end face 25a of the special ferrule 25 with a fiber is polished. Next, the special ferrule 25 with fiber
Is inserted into the ferrule mounting hollow portion 22b of the device holder 22 so that the polished surface (25a) faces the inside of the device holder 22, and is fixed with the adhesive. In the figure, the outer peripheral portion of the special ferrule 25 is fixed to the outer wall surface of the device holder 22 at the exit portion of the hollow portion 22b for mounting the ferrule. You may.

As described above, the device holder 22 to which the special ferrule 25 is fixed is fixed on an assembling device (not shown) to perform optical axis alignment. In the case of the optical module 20 on the light receiving side shown in FIG. The light receiving element 21 with the lens 35 is aligned as shown by the arrow in the device holder 22 while irradiating the light power of the lens 35, and the light receiving element 21 is positioned at the place where the light receiving element 21 receives the light most strongly. Adhesive 23 on the optical element mounting hollow portion 22a.
Fix with. Thus, the optical fiber 33 and the light receiving element 2
Since the optical axis alignment with 1 can be performed by active alignment by actually irradiating light and measuring the power, the optical axis alignment between the optical fiber 33 and the light receiving element 21 can be performed accurately and without variation. And the bonding characteristics can be stabilized. Although the optical axis alignment of the light emitting side optical module is not shown in detail, the light emitting element is aligned while emitting a predetermined amount of light from the CAN type light emitting element attached to the device holder, and passes through the optical fiber. The emitted light is measured with a power meter or the like, and the light emitting element and the device holder with the lens are bonded at a location where the desired optical power is received.

The optical module 20 has the following advantages as compared with the conventional optical module 1 shown in FIGS. 7 and 8 and the optical module 10 shown in FIG. Unlike a conventional structure in which a ferrule (SC ferrule) of an external optical connector is directly fitted into a device holder, connection with an external optical connector (MT-RJ connector 30 described later) is performed by an MT ferrule 32 and a device holder 22 is connected. Since the optical axis is not directly attached or detached, there is no problem that the optical axis is slightly shifted when attaching / detaching the connector, and the coupling characteristics are not stabilized. Optical element as described above (light receiving element 21 and light emitting element)
Is fixed after the active alignment, so that the processing accuracy and eccentricity of the special ferrule 25 do not greatly affect the coupling characteristics. Therefore, high processing accuracy and eccentricity are not required for the special ferrule 25, and the ferrule of the device holder 22 is mounted. A high processing accuracy is not required on the side of the hollow portion 22b, and the processing cost is reduced. The special ferrule 25 has a length of 8 mm.
Since the length of the optical module can be made sufficiently shorter than that of the ferrule 5a, the size of the optical module can be easily reduced. Further, since a metal tube is used, the rigidity of the ferrule can be easily secured.
Therefore, it is possible to reduce the diameter of the ferrule while securing the required outer diameter, and in this respect, it is also easy to realize the miniaturization of the optical module. Also, securing the outer diameter accuracy of the metal tube is easier than securing the outer diameter accuracy when the whole is a zirconia ferrule, and the outer diameter accuracy of the cylindrical body fitted into the metal tube is not so large. Since high precision is not required, the processing of the zirconia cylindrical body is relatively easy, and therefore, the ferrule can be manufactured at low cost. In addition, if a fiber hole is formed after the zirconia solid cylinder is fitted into the metal tube, the point that the outer diameter accuracy of the metal tube is easily secured is effectively utilized. In addition, the end face of the optical fiber 33 is polished by the end face polishing of the special ferrule 25 instead of being cut off, so that the performance does not deteriorate due to irregular reflection of light or the like. At the time of the above assembling, between the special ferrule 25 and the device holder 22, and between the light receiving element 21 and the device holder 22.
Adhesives 23 and 34 used for bonding between them may erroneously cause the polished surface 25a of special ferrule 25 or light receiving element 21 to fail.
When the light flows into the lens 35, the light coupling characteristics are greatly reduced. However, as described above, since the adhesive reservoir grooves 22c and 22d for preventing these are provided, the coupling by the flow of the adhesive is performed. There is no danger of deterioration in characteristics.

The cylindrical body fitted into the metal tube is not limited to ceramic such as zirconia, but may be plastic. In this case, according to the method of integrally molding the plastic ferrule in the metal tube by insert molding, it is easy to ensure the eccentricity of the fiber hole, and the accuracy of the outer diameter of the metal tube is more secure than in the case of zirconia processing. Therefore, a special ferrule having a required dimensional accuracy can be easily and inexpensively manufactured. In particular, when the cylindrical body is made of plastic, the metal pipe effectively functions to secure the rigidity of the special ferrule and maintain the dimensional accuracy (suppression of deterioration in accuracy due to aging).

FIGS. 4 to 6 show specific examples of an optical transceiver using the device holder type optical module of the present invention.
31 is an optical transceiver, 30 is this optical transceiver 31
Is connected to the MT-RJ connector (connector plug). Reference numeral 20 denotes the above-described light receiving side device holder type optical module, and reference numeral 40 denotes the light emitting side device holder type optical module. The light-emitting-side optical module 40 has basically the same structure as the light-receiving-side optical module 20, and includes a device holder 42 provided with a CAN-type light-emitting element (eg, a laser diode) 41 and a special ferrule 45. In this optical transceiver 31, the above-described two-core MT ferrule 32 to which the MT-RJ connector 30 can be fitted, the light-receiving side optical module 20 and the light-emitting side optical module 40 of the device holder type are connected by two optical fibers 33. The light receiving elements 21 of the optical modules 20 and 40 and the leads 21 a and 41 a of the light emitting element 41 are soldered to the substrate 46, and the plastic module is molded together with the receptacle 47 corresponding to the MT-RJ connector 30. 48 is an integrated configuration. In the illustrated example, the MT ferrule 32 is placed on a stage 50 fixed to a substrate 46, covered with a ferrule cover 51, and
0 and 40 are device holder tables 52 fixed to the substrate 46
Although installed above, the manner of installing the optical module is arbitrary. The MT-RJ connector 30 includes an MT ferrule 55 of a pin-fitting alignment type, and a plug housing 5.
6 and has a locking lever 54 for engaging with the receptacle 47. This MT
When the plug housing 56 is pushed into the receptacle 47 at the time of mounting, the wedge-shaped locking portion 54a provided at the tip of the locking lever 54 engages with the upper portion of the receptacle 47. The plug housing 56 and the receptacle 47 are engaged with each other by being fitted into the stop hole 47a, and at this time, the ferrules 55 and 32 are simultaneously connected in a state where the ferrules 55 and 32 are mutually aligned by the fitting pins 57. To release the plug, the operating knob 54b of the locking lever 54 is pushed down to release the locking portion 54a at the tip from the locking hole 47a of the receptacle 47. In this state, the plug is pulled out to the left in FIG. The housing 56 is detached from the receptacle 47.

Incidentally, the special ferrule in the present invention is as follows.
Instead of a stainless steel tube, a metal tube of another material can be used as the metal tube. In addition, other ceramic or plastic ferrules can be used instead of the zirconia ferrule.

[0018]

According to the device holder type optical module of the present invention, the other end of the optical fiber having one end fixed to the MT ferrule is inserted and fixed to a special ferrule having a structure in which a cylindrical body is fitted in a metal tube. Since the end face of the special ferrule with an optical fiber is polished and then housed and fixed in the ferrule mounting hollow portion of the device holder, the following effects are obtained. Since the optical axis of the optical fiber and the optical element can be aligned by active alignment, the optical axis can be aligned accurately and without variation, and the coupling characteristics are stabilized compared to the conventional structure using the SC ferrule. be able to. The connection with the external optical connector is M
Since it is performed with the T ferrule and is not directly attached to or detached from the device holder, there is no problem that the optical axis is slightly shifted when the connector is attached / detached and the coupling characteristics are unstable. Since the optical element is fixed after active alignment,
The processing accuracy and eccentricity of the special ferrule do not significantly affect the coupling characteristics, so high processing accuracy and eccentricity are not required for the special ferrule, and high processing accuracy is also required for the ferrule mounting hollow side of the device holder Processing cost is reduced. The special ferrule can be made sufficiently shorter than the SC ferrule having a length of 8 mm, so that the optical module can be easily downsized as compared with the conventional structure using the SC ferrule. Further, since a metal tube is used, the rigidity of the ferrule can be easily secured. Therefore, it is possible to reduce the diameter of the ferrule while securing the required rigidity, and in this regard, it is easy to realize the miniaturization of the optical module. Also, securing the outer diameter accuracy of the metal tube is easier than securing the outer diameter accuracy when the whole is a zirconia ferrule, and the outer diameter accuracy of the cylindrical body fitted into the metal tube is not so large. Since high precision is not required, the processing of the zirconia cylindrical body is relatively easy, and therefore, the ferrule can be manufactured at low cost. If you make a fiber hole after fitting a zirconia solid cylinder into the metal tube,
The point that it is easy to ensure the accuracy of the outer diameter of the metal tube is effectively utilized. Since the end face of the optical fiber is not cut off but polished by end face polishing of a special ferrule, the performance is not deteriorated due to irregular reflection of light or the like as compared with a conventional structure in which optical fibers are directly connected. According to the second or third aspect, since the adhesive collecting groove is provided in the peripheral portion of the hollow end portion for mounting the optical element or the hollow portion for mounting the ferrule, the optical fiber or the optical element is fixed to the device holder. There is no danger that the adhesive used for this purpose will erroneously flow into the polished surface of the special ferrule or the lens portion of the optical element, and there is no danger that the bonding characteristics will decrease due to the flow of the adhesive. The cylinder to be fitted into the metal tube is made of plastic,
If this is integrally molded with the metal tube by insert molding,
It is easy to secure the eccentricity of the fiber hole and the accuracy of the outer diameter of the metal tube is easier than in the case of zirconia processing. it can. When the cylindrical body is made of plastic, the metal pipe functions effectively to secure the rigidity of the special ferrule and maintain the dimensional accuracy (suppression of deterioration in accuracy due to aging).

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical module according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a part of the optical module of FIG. 1 from which an optical element is removed.

FIGS. 3A and 3B show a device holder in the optical module of FIG. 1, wherein FIG. 3A is a front view, FIG.
(C) is a right side view.

FIG. 4 is a front sectional view of an optical transceiver using the optical module and an MT-RJ connector connected to the optical transceiver.

FIG. 5 is a horizontal sectional view of FIG. 4;

FIG. 6 is a right side view of FIG. 1;

FIG. 7 is a sectional view of a conventional optical module.

8 is a schematic plan view illustrating an optical transceiver using the optical module of FIG.

FIG. 9 is a front sectional view of an optical transceiver using another conventional optical module.

[Explanation of symbols]

Reference Signs List 20 optical module of device holder type (optical module on light receiving side) 21 light receiving element (optical element) 22 device holder 22a hollow part for mounting optical element 22b hollow part for mounting ferrule 22c, 22d groove for storing adhesive 22e, 22f notch Part 23, 34 Adhesive 25 Special ferrule 26 Stainless steel tube (metal tube) 27 Zirconia ferrule (cylindrical body) 27a Fiber hole 30 MT-RJ connector 31 Optical transceiver 32 MT ferrule 33 Optical fiber 35 Lens 36 Lead 40 Device holder type light Module (light module on light emitting side) 41 Light emitting element 42 Device holder 45 Special ferrule 46 Substrate 47 Receptacle 55 MT ferrule 56 Plug housing 57 Fitting pin

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/13 10/12 (72) Inventor Yoshiya Isono 1440 Mutsuzaki Sakura City, Chiba Prefecture Fujikura Sakura Business Co., Ltd. Office (72) Inventor Makoto Osawa 1440, Misaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor, Tsutomu 1440, Misaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office, F-term (reference) 2H037 AA01 BA03 BA12 DA03 DA04 DA06 DA17 DA35 5F041 AA04 AA09 DC81 EE04 FF16 5F088 BA15 BB01 BB10 JA01 JA05 JA12 JA14 JA20 5K002 AA07 BA32 FA01

Claims (3)

[Claims] 1. An optical fiber having an optical element housed in an optical element mounting hollow part of a device holder and fixed with an adhesive, and one end of which is fixed to an MT ferrule as an optical connector part of an optical transceiver. A device holder type optical module to which a part is connected, wherein the other end of the optical fiber is inserted and fixed in a special ferrule having a structure in which a cylindrical body is fitted in a metal tube, and an end face of the special ferrule with the optical fiber. A device holder type optical module characterized in that after being polished, it is housed and fixed in a ferrule mounting hollow portion of a device holder. 2. The device holder type optical module according to claim 1, wherein a groove for accumulating an adhesive is formed in a peripheral portion of a rear end wall of the hollow portion for mounting the optical element. 3. The device holder type optical module according to claim 1, wherein a groove for storing an adhesive is formed in a peripheral portion of a rear end wall of the hollow portion for mounting the ferrule.