JP2008008933A - Manufacturing method of optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical module in which transmission loss can be set to a minimum in the optical branching part. <P>SOLUTION: The manufacturing method of the optical module includes: a process of preparing a first optical fiber provided with a first and a second terminal and mounted with a light emitting element in the first terminal; a process of preparing a second optical fiber; and a process of forming the optical branching part in which, in a state with the first and second optical fibers adjacently arranged nearly in parallel, the first and second optical fibers are extendedly joined while being heated, with the joined portion made the optical branching part. The process of forming the optical branching part is such that the light emitting element is made to emit light, that, while transmitted light emitted therefrom is detected in the second terminal of the first optical fiber, the first and second optical fibers are extendedly joined, and that, at the point of time when the intensity of the transmitted light is maximized, the extension is suspended to make the joined portion into the optical branching part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical module, and more particularly to a method for manufacturing an optical module for bidirectional communication having an optical branching unit.

An optical module used for bidirectional communication has, for example, a structure in which an optical fiber connected to a transmitting optical element and an optical fiber connected to a receiving optical element are connected by an optical branching unit.
Such an optical branching part is produced by, for example, arranging two optical fibers adjacently in parallel and stretching them while heating with a burner or the like, and fusing the optical fibers together. Here, the intensity of light passing through the light branching portion, that is, the transmission loss of the light branching portion, periodically changes as the optical fiber is stretched. Therefore, a master light source capable of emitting light having a wavelength used for transmission is connected to one end (first end) of the optical fiber to which the transmission optical element is connected, and the other end (second end) of the optical fiber. The optical fiber is stopped at the position where the intensity of the light emitted from the optical fiber becomes the highest, and the optical branching unit is produced. Finally, the optical fiber is sent to one end (first end) instead of the master light source. A trusted light element was attached (see, for example, Patent Document 1).
JP-A-8-271762

  However, the optical module manufactured by such a method has a problem that the intensity of light emitted from the second end varies. Therefore, the cause was examined, and the center wavelength of the transmitting optical element varies from element to element, and the master light source that emits light of a certain wavelength is used to set the transmission loss at the optical branching unit to a minimum. However, it was found that the transmission loss was larger than the setting when the transmission optical element was actually connected and used. Further, it has been found that the transmission loss increases even when the temperature rises due to the use temperature of the optical module or the heat generation of the transmitting optical element.

  Therefore, an object of the present invention is to provide an optical module manufacturing method that can set transmission loss at an optical branching portion to a minimum.

  The present invention is a method for manufacturing an optical module, comprising: preparing a first optical fiber having a first end and a second end, and having a light emitting element attached to the first end; In the state of preparing the optical fiber, and the first optical fiber and the second optical fiber adjacently arranged in parallel, the first optical fiber and the second optical fiber are stretch-bonded while heating, and the bonded portion is A light branching portion forming step, wherein the light branching portion forming step causes the light emitting element to emit light and detects transmitted light emitted from the light emitting element at the second end of the first optical fiber. An optical module characterized in that the optical fiber and the second optical fiber are stretch-bonded, and when the intensity of transmitted light reaches the maximum (maximum), the stretching is stopped and the bonded portion becomes a light branching portion. It is a manufacturing method.

  By using the method for manufacturing an optical module according to the present invention, it is possible to optimize the transmission loss of the optical branching unit according to the transmission optical element, and to provide an optical module with high luminous efficiency.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram of an optical module according to a first embodiment of the present invention, the whole being represented by 100. The optical module 100 is used by being incorporated in a modem for optical communication, for example.

  The optical module 100 includes a first optical fiber 1 and a second optical fiber 2. The first optical fiber 1 and the second optical fiber 2 are preferably optical fibers of the same standard, and are formed of a material such as glass or plastic.

  A transmitting optical element 3 is connected to one end of the optical fiber 1. As the transmitting optical element 3, for example, a Fabry-Perot type semiconductor laser, a distributed feedback (DFB type) semiconductor laser, a semiconductor module incorporating a surface emitting laser, or the like is used.

  The first optical fiber 1 and the second optical fiber 2 are connected to a third optical fiber 5 via an optical branching unit (fiber coupler) 4. Further, for example, a connector 6 for connecting to an external optical fiber network is connected to the end of the third optical fiber 5.

  As will be described later, the optical branching unit 4 is formed by fusing the first optical fiber 1 and the second optical fiber 2 together. The third optical fiber 5 is made of an optical fiber having the same standard as the first and second optical fibers 1 and 2. For example, the first optical fiber 1 and the third optical fiber 5 are formed from one optical fiber. And you may form the optical branching part 4 by melt | fusioning the 2nd optical fiber 2 to this.

  In the optical module 100, a transmission optical signal is emitted from the transmission optical element 3, and the transmission optical signal is transmitted from the connector 6 through the first optical fiber 1, the optical branching unit 4, and the third optical fiber 5 to external light. Is transmitted to the fiber network. For example, laser light having a center wavelength of 1310 nm is used for the transmission optical signal.

  On the other hand, the reception optical signal enters the third optical fiber 5 from the outside via the connector 6. As the reception optical signal, for example, laser light having a center wavelength of 1490 nm is used. The receiving optical signal that has entered the optical branching unit 4 from the third optical fiber 5 is branched by the optical branching unit 4 and enters the second optical fiber 2. For example, a light receiving element is provided at the end of the second optical fiber 2 to receive a reception optical signal transmitted through the second optical fiber 2.

  Here, the optical branching unit 4 is particularly formed so that the transmission loss of the transmission optical signal is minimized. Table 1 shows the relationship between the wavelength of transmitted light and the transmission loss when the optical branching unit 2 set so that the transmission loss of signal light having a wavelength of 1310 nm is minimized (0.15 dB). Is a graph of Table 1. In FIG. 2, the horizontal axis represents the wavelength of transmitted light, and the vertical axis represents the transmission loss.

[Table 1]

  In the optical module 100, as described above, for example, a Fabry-Perot type semiconductor laser having a center wavelength of 1310 nm is used for the transmission optical element 3, but in a commercially available Fabry-Perot type semiconductor laser, the center wavelength varies slightly for each semiconductor laser, Usually, there is a variation of about ± 20 nm with respect to the standard.

  That is, when a Fabry-Perot semiconductor laser having a center wavelength of 1310 nm is used, the actual center wavelength varies within the range of 1290 nm to 1330 nm. As a result, as can be seen from Table 1 and FIG. 2, the transmission loss also increases up to 0.28 dB. This is the reason why the transmission loss is larger than the setting in the conventional optical module.

On the other hand, in the optical module 100 according to the first embodiment, the optical branching unit 4 is manufactured so that the transmission loss is minimized at the actual center wavelength of the transmitting optical element 3. Thereby, it is possible to obtain the optical module 100 in which the transmission loss is always minimized.
Below, the manufacturing method of the optical module 100 is demonstrated.

  First, as shown in FIG. 3, the first optical fiber 1 is prepared. A transmitting optical element 3 having a predetermined center wavelength is connected to the end of the first optical fiber 1 in advance. A connector 6 is connected to the other end.

  Next, as shown in FIG. 4, the second optical fiber 2 is prepared. The second optical fiber 2 is made of an optical fiber having the same standard as the first optical fiber 1. The first optical fiber 1 and the second optical fiber 2 are fixed to fine movement bases 50 and 51 provided on a stage (not shown) of a heating and stretching apparatus in a state where they are adjacently arranged in parallel. The fine movement base 51 is connected with a driving device 60 and a controller 70 for controlling the driving device 60. A memory 80 in which data described in the second embodiment is stored is connected to the controller 70.

  By the driving device 60 controlled by the controller 70, the fine movement base 51 slowly moves at a constant speed in the direction of extending the first optical fiber 1 and the second optical fiber 2 on the stage. The heating and stretching apparatus further includes a burner 52 that heats and fuses the first optical fiber 1 and the second optical fiber 2 between the two fine movement bases 50 and 51.

  Next, in a state where the first optical fiber 1 and the second optical fiber 2 are fixed to the fine movement bases 50 and 51, the transmission optical element 3 is caused to emit light and the signal light is sent to the optical fiber 1. An optical power meter 20 is connected to the connector 6 and measures the intensity of light emitted from the optical fiber 1. Here, the optical power meter 21 is also connected to the end of the second optical fiber 2.

  Next, in a state where the transmission optical element 3 is caused to emit light, the first optical fiber 1 and the second optical fiber 2 are heated by the burner 52, the fine movement base 51 is moved, and the first optical fiber 1 and the second optical fiber 2 are moved. The optical fiber 2 is stretched. As a result, the first optical fiber 1 and the second optical fiber 2 are fused while being stretched (stretch joining step), and the stretched and joined portion becomes the light branching portion 4.

  FIG. 5 shows the relationship between the stretching time and the light intensity measured by the optical power meters 20 and 21 during the stretching and bonding process. In FIG. 5, the solid line indicates the light intensity measured with the optical power meter 20, and the broken line indicates the light intensity measured with the optical power meter 21.

  As can be seen from FIG. 5, the light intensity changes periodically, and it can be seen that the transmission loss of the light branching portion 4 periodically changes according to the drawing time (or drawing distance) in the drawing and joining step. It can also be seen that the light intensity of the light (branched light) measured by the optical power meter 21 is minimized (minimum) under the condition that the light intensity measured by the optical power meter 20 is maximized (maximum).

  Here, the movement of the fine moving base 51 is stopped at the time indicated by the symbol A in FIG. 5, and the length of the optical branching unit 2 is fixed.

  Finally, the first optical fiber 1 and the second optical fiber 2 joined at the optical branching unit 2 are removed from the fine movement bases 50 and 51, and the second optical power meter 21 side (right side in FIG. 4) from the optical branching unit 4 is removed. By cutting the optical fiber 2, an optical module 100 as shown in FIG. 1 is obtained.

  Depending on the specifications of the optical module, the second optical module 2 may be left as it is without being cut. In FIG. 1, the first optical fiber 1 and the third optical fiber 5 are connected with the optical branching portion 4 interposed therebetween, but the first optical fiber 1 is connected to both sides of the optical branching portion 4. The form is substantially the same.

  Further, here, the movement of the fine movement base 51 is stopped when the light intensity measured by the optical power meter 20 reaches the maximum (maximum), but as is apparent from FIG. The movement of the fine movement base 51 may be stopped when the light intensity becomes minimum (minimum).

  As described above, in the optical module 100 manufactured by the manufacturing method according to the first embodiment, the transmission optical element 3 is connected to the optical fiber 1 in advance, and the transmission loss of the signal light emitted from the transmission optical element 3 is minimized. By manufacturing the optical branching unit 4 so as to satisfy the above, it is possible to always minimize the transmission loss of the optical branching unit 4 and to provide an optical module with high transmission efficiency and no variation in performance.

  Further, depending on the specifications of the optical module, the movement of the fine movement table 51 may be stopped when the light intensity measured by the optical power meter 21 reaches the maximum (maximum).

Embodiment 2. FIG.
In the first embodiment, the optical module 100 is manufactured so that the transmission loss of the signal light emitted from the transmission optical element 3 is minimized, but the light emission of the Fabry-Perot semiconductor laser incorporated in the transmission optical element 3 The wavelength varies depending on the environmental temperature (ambient temperature). For example, when the environmental temperature changes once, the center wavelength (λ) changes by 0.45 nm. Therefore, for example, when the environmental temperature changes (increases or decreases) in a range of ± 20 degrees, the shift amount (Δλ) of the center wavelength becomes ± 9 nm (0.45 nm × 20).

  As described in the first embodiment, the variation in the center wavelength of the Fabry-Perot semiconductor laser is about ± 20 nm between elements. Therefore, in the conventional optical module, when the environmental temperature changes by 20 degrees, the actual center wavelength varies about ± 30 nm at the maximum with respect to the desired center wavelength. As a result, as can be seen from Table 1, the transmission loss increases to a maximum of 0.43 dB.

  In the manufacturing method according to the second embodiment, the environmental temperature at which the optical module 100 is used is examined in advance, and the optical branching unit 4 is produced so that the transmission loss at the environmental temperature is minimized.

  That is, as in the case of the first embodiment, the first and second optical fibers 1 and 2 are fixed to the fine movement bases 50 and 51 of the heating and stretching apparatus, and the stretching and joining process is performed. Here, for example, if the temperature (room temperature) at which the stretch bonding process is performed is 25 ° C. and the environmental temperature at which the optical module 100 is actually used is 20 ° C., the temperature difference between the two is 5 degrees. When the temperature changes by 5 degrees, the shift amount (Δλ) of the center wavelength (λ) of the semiconductor laser becomes 2.25 nm (0.45 nm / degree × 5 degrees).

  Accordingly, when a semiconductor laser having a center wavelength of 1310 nm is used for the transmitting optical element 3, the optical branching unit 4 is set so that the transmission loss with respect to signal light having a wavelength of 1307.75 nm (1310 nm-2.25 nm) is minimized. It will be produced.

  Actually, in the stretching and joining process, data is acquired in advance as to how the wavelength of the signal light transmitted through the optical branching section 4 with the minimum transmission loss changes depending on the stretching time (or stretching distance). Create a database. For example, it is preferable to obtain data in which the wavelength of the signal light transmitted with the minimum transmission loss is plotted on the vertical axis corresponding to the time indicated on the horizontal axis of FIG. Such a database is stored in the memory 80.

  Then, based on such data, in the stretch bonding process, the movement of the fine movement base 51 is stopped at the time when the transmission loss of light having a wavelength of 1307.75 nm is minimized (corresponding to symbol B in FIG. 5), and the optical branching unit 4 Fix the length of. Note that the point at which the transmission loss of light of a predetermined wavelength is minimized appears periodically according to the stretching time (or stretching distance).

  Finally, the first optical fiber 1 and the second optical fiber 2 joined by the optical branching unit 4 are removed from the fine movement bases 50 and 51, and the second optical power meter 21 side (right side in FIG. 4) from the optical branching unit 4. The optical module 100 is obtained by cutting the optical fiber 2.

  As described above, in the manufacturing method according to the second embodiment, the optical branching section 4 can be manufactured so that the transmission loss is minimized at the environmental temperature at which the optical module is actually used.

Embodiment 3 FIG.
FIG. 6 shows the relationship between the drive current of the optical module and the optical output. In FIG. 6, the horizontal axis indicates the drive current supplied to the transmitting optical element, and the vertical axis indicates the light intensity emitted from the optical module. FIG. 6 shows the case where the environmental temperature for driving the semiconductor laser is 0 ° C., 20 ° C., and 40 ° C.

  As can be seen from FIG. 6, when the drive current is constant, the output of the light emitted from the optical module decreases as the environmental temperature increases. This is because, as described above, the center wavelength of the semiconductor laser changes depending on the environmental temperature.

  Such a change in the environmental temperature is also caused by, for example, heat generated when the semiconductor laser included in the optical module is driven.

  Therefore, the manufacturing method according to the third embodiment provides an optical module in which the transmission loss is reduced when the center wavelength of the semiconductor laser changes due to heat generated by driving the semiconductor laser.

  Also in this case, the change in the environmental temperature due to the heat generated by the semiconductor laser is examined in advance, and the light transmitting portion 4 is produced in response to the temperature change as in the second embodiment.

For example, if the environmental temperature at the time of manufacturing the optical module is 25 ° C., and the environmental temperature due to heat generation at the time of driving the semiconductor laser is 40 ° C., the temperature change is 15 degrees, and the wavelength shift amount (Δλ) is 6.75 nm (0. 45 nm / degree × 15 degrees).
Accordingly, when a semiconductor laser having a center wavelength (λ) of 1310 nm is used for the transmitting optical element 3, the optical branching unit 4 is set so that the transmission loss with respect to signal light having a wavelength of 131.75 nm (1310 nm + 6.75 nm) is minimized. Will be produced.

  As in the case of the second embodiment, in practice, the wavelength of the signal light transmitted through the optical branching section 4 with the minimum transmission loss in advance in the stretching joining step depends on the stretching time (or stretching distance). How to change the database. Then, based on such data, in the stretch bonding step, the movement of the fine movement base 51 is stopped when the transmission loss of light having a wavelength of 1316.75 nm is minimized, and the length of the light branching unit 4 is fixed.

  In the method according to the third embodiment, the intensity of transmitted light during the stretch bonding process is further measured with the optical power meter 20 as in the case of the first embodiment. Here, as described above, the point at which the transmission loss of light having a wavelength of 1311.65 nm is minimized appears periodically, for example, points represented by symbols C and D in FIG.

  In the third embodiment, while detecting the intensity of the transmitted light with the optical power meter 20, the drawing and joining process is stopped at the time represented by C among the two points C and D having the same transmission loss, and the optical branching is performed. The length of the part 4 is fixed. That is, a point C is selected so that the light intensity of the transmitted light through the first optical fiber increases as the first optical fiber is stretched just before the time when the stretching is stopped.

  This is to prevent the light intensity from being lowered even when the length of the photoconductive portion 4 is longer than the produced length due to heat generated when the semiconductor laser is driven.

  In addition, while detecting the intensity of the transmitted light with the optical power meter 20, a point where the light intensity of the transmitted light decreases according to the stretching time may be selected.

  Finally, the first optical fiber 1 and the second optical fiber 2 joined by the optical branching unit 4 are removed from the fine movement bases 50 and 51, and the second optical power meter 21 side (right side in FIG. 4) from the optical branching unit 4. The optical module 100 is obtained by cutting the optical fiber 2.

  As described above, in the manufacturing method according to the third embodiment, the optical branching unit 4 can be manufactured so that the transmission loss is minimized when the optical module generates heat by operation.

  In the above first to third embodiments, the case where a Fabry-Perot type semiconductor laser is used for the transmitting optical element 3 has been described. However, the same applies to the case where a distributed feedback type semiconductor laser, a surface emitting laser, or the like is used. .

It is the schematic of the optical module concerning Embodiment 1 of this invention. This is the relationship between the wavelength of light incident on the light branching portion and transmission loss. It is a manufacturing-process figure of the optical module concerning Embodiment 1 of this invention. It is a manufacturing-process figure of the optical module concerning Embodiment 1 of this invention. It is the relationship between the time and optical intensity in the extending | stretching joining process of the optical module concerning Embodiment 1 of this invention. It is the relationship between the drive current and optical output of an optical element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st optical fiber, 2nd optical fiber, 3 Optical element for transmission, 4 Optical branch part, 5 3rd optical fiber, 6 Connector, 20, 21 Optical power meter, 50, 51 Fine movement base, 52 Burner, 60 Drive Device, 70 controller, 80 memory, 100 optical module.

Claims (5)

An optical module manufacturing method comprising:
Preparing a first optical fiber having a first end and a second end, and a light emitting element attached to the first end;
Preparing a second optical fiber;
In a state where the first optical fiber and the second optical fiber are disposed adjacent to each other in a substantially parallel manner, the first optical fiber and the second optical fiber are stretched and bonded while heating, and the bonded portion is defined as an optical branching portion. An optical branching portion forming step,
The light branching portion forming step includes
The light emitting element emits light, and the first optical fiber and the second optical fiber are stretched and bonded while detecting the transmitted light emitted from the light emitting element at the second end of the first optical fiber, and the transmitted light A method of manufacturing an optical module, comprising: a step of stopping stretching at a time when the strength of the optical fiber reaches a maximum and making the joining portion a light branching portion. An optical module manufacturing method comprising:
Preparing a first optical fiber having a first end and a second end, and a light emitting element attached to the first end;
Providing a second optical fiber having a first end and a second end;
In a state where the first optical fiber and the second optical fiber are disposed adjacent to each other in a substantially parallel manner, the first optical fiber and the second optical fiber are stretched and bonded while heating, and the bonded portion is defined as an optical branching portion. An optical branching portion forming step,
The light branching portion forming step includes
The light emitting element emits light, and the first optical fiber and the second optical fiber are stretched and joined while detecting the transmitted light emitted from the light emitting element at the second end of the second optical fiber, and the transmitted light A method of manufacturing an optical module, which is a step of stopping stretching when the strength of the optical fiber reaches the maximum or minimum and making the joining portion a light branching portion. An optical module manufacturing method comprising:
Preparing a first optical fiber having a first end and a second end, and a light emitting element attached to the first end;
Preparing a second optical fiber;
In a state where the first optical fiber and the second optical fiber are arranged substantially parallel and adjacent to each other, the first optical fiber and the second optical fiber are stretched and joined while heating, and the joint portion is optically branched. An optical branching part forming step to be a part,
The light branching portion forming step includes
Calculate the shift amount Δλ of the center wavelength due to the temperature difference between the environmental temperature where the optical branching portion forming step is performed and the environmental temperature where the optical module is used,
A stretch correction amount is obtained from the database from the shift amount Δλ,
An optical module comprising: a step of stopping stretching when the intensity of transmitted light of the light-emitting element is maximized and correcting the amount by the stretching correction amount to make the joint portion a light branching portion. Production method.   The said database consists of a database which calculated | required the relationship between the extending | stretching amount of the said 1st optical fiber, and the intensity | strength of the transmitted light of this 1st optical fiber for every transmitted light of a different wavelength. Manufacturing method of optical module. An optical module manufacturing method comprising:
Preparing a first optical fiber having a first end and a second end, and a light emitting element attached to the first end;
Preparing a second optical fiber;
In a state where the first optical fiber and the second optical fiber are disposed adjacent to each other in a substantially parallel manner, the first optical fiber and the second optical fiber are stretched and bonded while heating, and the bonded portion is defined as an optical branching portion. An optical branching portion forming step,
The light branching portion forming step includes
A step of causing the light emitting element to emit light and extending and joining the first optical fiber and the second optical fiber while detecting transmitted light emitted from the light emitting element at the second end of the first optical fiber. ,
Calculate the shift amount Δλ of the center wavelength due to the temperature difference between the environmental temperature where the optical branching portion forming step is performed and the environmental temperature where the optical module is used,
A stretch correction amount is obtained from the database from the shift amount Δλ,
From the time when the intensity of the transmitted light of the light emitting element is maximized, the stretching is stopped at the time when the stretching correction amount is corrected, and the joining portion is a light branching portion.
A method of manufacturing an optical module, wherein the light intensity of the transmitted light that has passed through the first optical fiber is increased in accordance with the stretching immediately before the time when the stretching is stopped.

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