JP4012537B2 - Optical module and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical module used for optical demultiplexing and multiplexing in the field of optical communication and the like.

FIG. 8 shows an optical multiplexer / demultiplexer described in Patent Document 1 as an example of a conventional configuration of this type of optical module. In this example, the optical multiplexer / demultiplexer 110 is provided to face each other. The first optical system (first collimator) 120, the second optical system (second collimator) 130, the wavelength selection filter 140, and the cylindrical outer holder for holding the first optical system 120 and the second optical system 130. 150.
The first optical system 120 holds optical fibers 121 and 122, a cylindrical fiber holder 123 that holds these optical fibers 121 and 122, a cylindrical rod lens 124, and a fiber holder 123 and a rod lens 124. The optical fibers 121 and 122 are inserted and held in the fiber holder 123, and their end faces are arranged so as to be flush with the inclined surface 123c of the fiber holder 123. ing. The fiber holder 123 and the rod lens 124 are fixed to the inner surface of the inner holder 125 with an adhesive 127.

The second optical system 130 includes an optical fiber 132, a fiber holder 123 that holds the optical fiber 132, a rod lens 124, and an inner holder 125 that holds the fiber holder 123 and the rod lens 124. The configuration is the same as that of the first optical system 120 except that the number of the fibers 132 is one.
The wavelength selection filter 140 is disposed on the end surface of the rod lens 124 of the first optical system 120. In FIG. 8, reference numeral 142 denotes an adhesive for bonding the wavelength selection filter 140 to the rod lens 124.

The first optical system 120 and the second optical system 130 on which the wavelength selection filter 140 is disposed are fixed to the inner surface of the outer holder 150 by an adhesive 152, thereby configuring the optical multiplexing / demultiplexing device 110.
For example, when optical demultiplexing is performed using the optical multiplexer / demultiplexer 110 having the above-described configuration, a wavelength multiplexed signal (wavelength multiplexed light) is input from the optical fiber 121 to the optical multiplexer / demultiplexer 110. .
Light input from the optical fiber 121 is converted into parallel light by the rod lens 124 and guided to the wavelength selection filter 140, and light of a specific wavelength passes through the wavelength selection filter 140 and is transmitted by the rod lens 124 of the second optical system 130. The light is condensed and guided to the optical fiber 132. On the other hand, of the light guided to the wavelength selection filter 140, light of other wavelengths is reflected by the wavelength selection filter 140, and this reflected light is collected by the rod lens 124 and guided to the optical fiber 122, and thus The light is demultiplexed.

In the optical multiplexer / demultiplexer 110 that functions as described above, for example, the fiber holder 123 and the wavelength selection filter are coupled so that the light input from the optical fiber 121 in the first optical system 120 is coupled to the optical fiber 122 with low loss. Alignment in the three-axis (X, Y, and Z-axis) directions with the rod lens 124 on which 140 is arranged is performed, and after alignment, for example, an ultraviolet curable adhesive is used for the inner holder 125 And fixed by bonding.
Similarly, the fiber holder 123 and the rod lens 124 of the second optical system 130 are also aligned and fixed to the inner holder 125 using an ultraviolet curable adhesive. Furthermore, the light input from the optical fiber 121 of the first optical system 120 and transmitted through the wavelength selection filter 140 is incident on the second optical system 130 and is coupled to the optical fiber 132 with low loss. And the second optical system 130 are aligned, and after alignment, these are bonded and fixed to the outer holder 150 using an ultraviolet curable adhesive.

That is, a fast-acting UV curable adhesive is used for fixing after alignment in order to bond and fix the alignment state in place without destroying the alignment state. The outer holder 150 is made of a glass material that can transmit ultraviolet rays.
JP 2002-90573 A

  As described above, in the conventional structure shown in FIG. 8, the fiber holder 123 and the rod are bonded to the inner holder 125 of the fiber holder 123 and the rod lens 124 in the first optical system 120 and the second optical system 130. Each outer peripheral surface of the lens 124 is bonded to the inner peripheral surface of the inner holder 125. Similarly, the first optical system 120 and the second optical system 130 are also bonded and fixed to the outer holder 150. The outer peripheral surface of each inner holder 125 of the first and second optical systems 120 and 130 and the inner peripheral surface of the outer holder 150 are bonded. This causes the following problems.

That is, the gap between the outer peripheral surface of the fiber holder 123 and the rod lens 124 and the inner peripheral surface of the inner holder 125 and the gap between the outer peripheral surface of the inner holder 125 and the inner peripheral surface of the outer holder 150 are aligned. Since it is necessary to secure the adjustment range in order to carry out, a relatively large gap is provided.
On the other hand, since adhesives generally shrink when cured, including UV curable adhesives, for example, the relationship between the fiber holder 123 and the inner holder 125 is illustrated in FIG. If there is a deviation, the fiber holder 123 is pulled toward the thicker adhesive layer as indicated by the arrow 128, and thus the fiber holder 123 moves and deviates from the alignment position. Actually, the cure shrinkage rate of the epoxy resin adhesive is nearly 4%, and the influence of the cure shrinkage of such an adhesive is large and cannot be ignored.

In addition, for example, when the bonding area is widened, it becomes extremely difficult to apply the adhesive uniformly around the fiber holder 123 and the rod lens 124 and without bubbles, and thus the adhesive layer becomes non-uniform, When air bubbles enter, the stress acting on the fiber holder 123 and the rod lens 124 when the adhesive cures and shrinks becomes non-uniform so that the gap after alignment is uniform and uniform. However, it may occur that the position is shifted from the alignment position.
FIG. 10 shows the light input from the optical fiber 121 when the fiber holder 123 holding the optical fibers 121 and 122 is displaced in the radial direction (X, Y direction) from the position aligned with the rod lens 124. The coupling loss (reflection coupling loss) to the optical fiber 122 is shown, and it can be seen from FIG. 10 that a loss of about 0.7 dB occurs only by shifting by 1 μm in the X and Y directions. In this type of optical module for communication (optical multiplexer / demultiplexer), generally, such a coupling loss has an allowable value (required value) of about 0.6 dB, and the occurrence of such misalignment is fatal. It becomes a problem.

In addition, adhesives generally have a large coefficient of thermal expansion, so the conventional bonding method that thickens the adhesive layer increases the temperature dependence of the coupling loss, which has a large effect on performance and is inferior in temperature stability. It becomes.
In view of such a problem, an object of the present invention is to provide an optical module that can suppress performance deterioration due to adhesive fixation after alignment and has excellent temperature stability.

According to the first aspect of the invention, the ends of the two optical fibers are arranged in parallel to each other, and the light emitted from the end face of one of the optical fibers is transmitted through the lens and incident on the optical filter. In the optical module having at least an optical system in which the reflected light reflected again passes through the lens and enters the end face of the other optical fiber, the terminal has a cylindrical shape whose optical axis and the central axis are parallel to each other. Inserted and held in an optical fiber holder , the optical fiber holder is inserted into a cylindrical sleeve that can be axially adjusted by inserting the optical fiber holder, aligned in the axial direction, and paired with each other. The contact surface is bonded and fixed, and the lens and the optical filter are received and fixed in the holder. The holder is abutted against the end surface of the sleeve, and the sleeve is positioned in a direction perpendicular to its axis. Having an adjustable plane, and the sleeve and the holder is aligned with the vertical direction, it is intended to contact face each other are adhered and fixed.

  In the invention of claim 2, in the invention of claim 1, at least one of the sleeve and the holder is made of a material that transmits light, and a photo-curing adhesive is used for the adhesive fixing of the sleeve and the holder. .

  According to this invention, the sleeve is provided, the optical fiber holder and the sleeve are aligned and fixed in the axial direction, and the end surface of the sleeve is abutted against the holder holding the lens and the optical filter. Due to the structure in which the contact surfaces are bonded and fixed in the vertical direction, alignment performance deterioration due to adhesive curing and shrinkage in adhesive fixing after alignment can be suppressed, and temperature stability An optical module with excellent properties can be obtained.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of an optical module according to the present invention. In this example, the optical module has the same function as the conventional optical multiplexer / demultiplexer shown in FIG. It is used for demultiplexing and multiplexing.
The ends of the two optical fibers 11 and 12 from which the coating has been removed are inserted and held in the optical fiber holder 13. The optical fiber holder 13 has a cylindrical shape, and two fine holes 13a are formed in the center of the optical fiber holder 13 in parallel with the central axis. The ends of the optical fibers 11 and 12 are inserted into the fine holes 13a and are parallel to each other. These optical axes are parallel to the central axis of the optical fiber holder 13. On the side where the optical fibers 11 and 12 are inserted, a taper 13b for guiding is provided so that the optical fibers 11 and 12 can be easily inserted. The optical fibers 11 and 12 are fixed to the optical fiber holder 13 using an adhesive or the like.

The end faces (tip faces) of the optical fibers 11 and 12 held by the optical fiber holder 13 are located on the same plane as the end face 13c of the optical fiber holder 13, and detailed illustration is omitted in FIG. The end face 13c is generally subjected to oblique polishing in order to suppress the return loss, and an antireflection film is generally formed on the polished face in order to suppress reflection loss.
The optical fiber holder 13 holding the optical fibers 11 and 12 is inserted into a sleeve 14 that is a cylindrical body, aligned in the axial direction (Z direction), and the surfaces facing each other are bonded and fixed.

  The holder 15 is formed in a cylindrical shape, and concave portions 15c and 15d are formed to communicate with each other from both end faces 15a and 15b, respectively, and a lens 16 that forms a sphere is accommodated and fixed in one concave portion 15c. The optical filter 17 is housed and fixed in the recess 15d. The bottom surface of the recess 15c may be a simple through hole, but may be a countersink shape so that the lens 16 can be positioned. The optical filter 17 is formed by forming a filter film 17 a on one surface of a transparent substrate such as glass. The filter film 17 a is housed on the inner surface side, that is, facing the lens 16. The lens 16 and the optical filter 17 are fixed to the holder 15 using, for example, an adhesive.

The holder 15 holding the lens 16 and the optical filter 17 is in contact with the end surface 14a of the sleeve 14 at the end surface 15a on the side where the lens 16 is located, and is aligned in the in-plane direction (X, Y direction). The contact surface is fixed by adhesion.
On the other hand, a disk-shaped holder 18 is disposed on the other end surface 15 b of the holder 15 by being bonded and fixed, and a spherical lens 19 is attached to the holder 18. A through-hole 18a is formed in the center of the holder 18, and a through-hole 18a is formed in a surface 18c opposite to the surface 18b that contacts the holder 15. A lens 19 is positioned and bonded and fixed thereto. ing. The through-hole 18a may be a simple through-hole, but as shown in the figure, a countersink-shaped recess 18d formed by expanding the diameter may be formed.

A cylindrical sleeve 20 is abutted against and fixed to the surface 18c of the holder 18 by an end face 20a, and an optical fiber holder 21 is inserted and fixed to the sleeve 20. Like the optical fiber holder 13, the optical fiber holder 21 has a cylindrical shape and has a pore 21a having a taper 21b. The end from which the coating of the optical fiber 22 has been removed is inserted and held in the pore 21a, and its optical axis is parallel to the central axis of the optical fiber holder 21. The optical fiber 22 is fixed to the optical fiber holder 21 using an adhesive or the like.
The end face 21c of the optical fiber holder 21 where the end face of the optical fiber 22 is located is not shown in detail. However, like the end face 13c of the optical fiber holder 13, it is generally subjected to oblique polishing and further an antireflection film is formed. A film is formed.

The holder 15 and the holder 18 and the holder 18 and the sleeve 20 are aligned and fixed in the in-plane direction (X, Y direction) in contact with each other, and the sleeve 20 and the optical fiber holder 21 are axially ( (Z direction) and aligned and fixed.
Each part formed by bonding and integration as described above is housed in a cylindrical cover 23 in this example. In FIG. 1, 24 indicates a filler.
In the optical module configured as described above, for example, light emitted from the end face of the optical fiber 11 passes through the lens 16 and enters the optical filter 17, and the reflected light reflected by the optical filter 17 is again reflected in the lens 16. The transmitted light that has passed through the optical filter 17 passes through the lens 19 and enters the end face of the optical fiber 22.

Next, a method for positioning and fixing each part of the optical module having such a configuration will be described in detail.
(1) A fiber Assy 1A in which the optical fibers 11 and 12 are held by the optical fiber holder 13 is inserted into the sleeve 14, and the lens 16 and the optical filter 17 are aligned with the lens Assy 1B in which the holder 15 is housed and fixed. Set in the device. The lens Assy 1B is fixed to the aligning device, while the fiber Assy 1A is disposed right above the lens Assy 1B and is attached to an arm that can move in three axial directions of X, Y, and Z. In this state, the sleeve 14 into which the fiber Assy 1A is inserted has its end face 14a in contact with the end face 15a of the holder 15 in a free fall state. Light is incident on the optical fiber 11 from a light source, and an optical power meter for optical monitoring is connected to the optical fiber 12.

(2) Move the arm of the alignment device and adjust the position of the fiber Assy 1A so that the instruction of the optical power meter is maximized. When the instruction from the optical power meter reaches the maximum, the sleeve 14 and the optical fiber holder 13 are fixed with an adhesive. There are various methods for bonding and fixing as shown in the following (a) to (d), and any of these methods is used.
(A) A method of fixing with an ultraviolet curable adhesive (b) A method of using an ultraviolet curable adhesive of a thermosetting combination type, curing with ultraviolet rays, removing from the arm and thermally curing (c) For example, instant bonding (D) After bonding by any of the above methods (a) to (c) and further removing from the arm, the bonding strength and durability are further improved. A method of reinforcing the fixation by applying a thermosetting epoxy adhesive, for example, to the boundary part between the two members on the outer periphery of the bonding surface. In view of the fact that the adhesive is an adhesive suitable for temporary fixing and is not excellent in terms of adhesive strength and durability in a high-temperature and high-humidity environment, it is a suitable method.

  (3) The fiber Assy 1A to which the sleeve 14 is bonded and fixed is abutted against the opposing end surface 15a of the holder 15, and after realignment, fixed with an adhesive. The timing at which the adhesive is applied to the end face 14a of the sleeve 14 is a method in which realignment is performed before or after realignment, and then the fiber Assy 1A is pulled up in the Z direction to apply the adhesive, and realignment (fine adjustment) is performed. . Adhesion is a condition that the adhesive is cured without being removed from the alignment apparatus in the alignment state, and thus a fast-acting adhesive is used. As in the method, (a) to (d) Either method is used.

As described above, the positioning and fixing (alignment fixing) of the optical Assy 1 including the fiber Assy 1A, the sleeve 14, and the lens Assy 1B is completed. FIG. 2 shows the optical assembly 1 manufactured as described above. In the figure, reference numeral 25 denotes an adhesive that bonds the sleeve 14 and the holder 15 together. The illustration of other adhesives is omitted.
The alignment of the optical Assy 2 including the fiber Assy 2A in which the optical fiber 22 is held by the optical fiber holder 21, the sleeve 20 and the lens Assy 2B in which the lens 19 is fixed to the holder 18 is also described above. This can be performed in the same manner as the alignment fixing. In this optical assy 2 alignment fixing method, a method of actually using the optical assy 2 and the other side optical assy 1 assembling the optical module as a light source, and other methods having the same characteristics as the optical assy 1 described above, for example, are prepared. There is a method of preparing as a jig (equipment) for the core. The counterpart optical Assy 1 is attached and fixed to an arm movable in three axial directions, or the above-mentioned alignment jig is fixed to the alignment apparatus, and the lens Assy 2B is on the optical Assy 1 or adjusted. Positioned and mounted on a core jig. An optical power meter for optical monitoring is connected to the optical fiber 22, and the alignment is fixed in the same manner as in the above (1) to (3) by emitting light from the counterpart optical assembly 1 or alignment jig. Done. However, when the counterpart optical Assy 1 is used as a light source here, two arms, an arm for attaching and fixing the optical Assy 1 and an arm for attaching and adjusting the position of the fiber Assy 2A, are combined. Will be used.

The alignment fixing of the optical Assy 1 and the optical Assy 2 is performed as follows.
That is, when the other party optical Assy 1 is used, light is continuously incident on the optical fiber 11 with the setting as it is, and adjustment is performed by moving either the optical Assy 1 or the optical Assy 2 arm. can do. When the alignment jig described above is used, the optical Assy 2 is fixed to the alignment apparatus, and an optical power meter for optical monitoring is connected to the optical fiber 22. The optical Assy 1 is disposed immediately above the optical Assy 2 and is attached to an arm that is movable in the three-axis directions of X, Y, and Z. Light enters the optical fiber 11 from a light source.

The arm is moved, and the position of the optical assembly 1 is adjusted so that the instruction of the optical power meter is maximized. When the instruction of the optical power meter reaches the maximum, an adhesive is applied to the opposing surfaces of the holder 15 and the holder 18 and fixed. Any one of the methods (a) to (d) described above is used as the adhesive fixing method, and the alignment of the optical assembly 1 and the optical assembly 2 is performed in this way.
Finally, as described above, the optically assembled optical assembly 1 and optical assembly 2 are accommodated in the cover 23, and the optical fibers 11, 12, and 22 are to be protected in the gap between the optical assembly 1, 2 and the cover 23. A filler 24 such as silicone resin is filled as necessary. The cover 23 is preferably longer than the roots of the optical fiber holders 13 and 21 of the optical fibers 11, 12, and 22, respectively, so that the optical fibers 11, 12, and 22 are not easily broken at the roots. In addition, the optical fiber holders 13 and 21 are less susceptible to external force due to contact or the like.

In addition, in the case of using the method of using the adhesive fixing method (a) or (b) for bonding each part, it is necessary to form at least one of both members to be bonded with a material that transmits ultraviolet rays. There is. In this example, an ultraviolet curable adhesive is used, the optical fiber holder 13, the sleeve 14, the holder 18, and the optical fiber holder 21 are made of glass that transmits ultraviolet rays, and the holder 15 and the sleeve 20 are made of stainless steel.
Further, for example, in the bonding between the sleeve 14 and the holder 15, the bonding between the sleeve 20 and the holder 18, and the bonding between the holder 15 and the holder 18, it is preferable to use the bonding fixing method (d), that is, the axis (Z axis). After adhering the bonding surface (contact surface) of both members composed of surfaces perpendicular to the surface with an ultraviolet curable adhesive or the like, a thermosetting adhesive is placed on the boundary between the two members on the outer periphery of the bonding surface. It is desirable to cure and reinforce mechanical strength.

FIG. 3 shows a light ray diagram of the optical module configured as described above. In this example, light is input from the optical fiber 11, in which 31 indicates input light, 32 Indicates reflected light, and 33 indicates transmitted light.
Input light (wavelength multiplexed light) 31 emitted from the end face of the optical fiber 11 is converted into parallel light by the lens 16 and is incident on the optical filter 17, and light having a specific wavelength passes through the optical filter 17. The transmitted light 33 is collected by the lens 19 and enters the end face of the optical fiber 22. On the other hand, of the light incident on the optical filter 17, light of other wavelengths is reflected by the optical filter 17, and the reflected light 32 is collected by the lens 16 and enters the end face of the optical fiber 12. In this way, the light is demultiplexed.

The distance L1 between the end surface 13c of the optical fiber holder 13 and the center of the lens 16 and the distance L2 between the center of the lens 16 and the filter surface (filter film 17a) of the optical filter 17 are both the same as the focal length of the lens 16. The distance L4 between the center of the lens 19 and the end face 21c of the optical fiber holder 21 is set to the same length as the focal length of the lens 19.
By the way, for example, if the lens 16 and the lens 19 have the same characteristics, in order to couple the transmitted light 33 to the optical fiber 22 with low loss, the positions of a and b on the circumference of the lens 16; The positions of c and d on the circumference of the lens 19 need to be the same position (the same angular position) with respect to the optical axes 34 and 35, respectively.

Here, L2 set to the same length as the focal length of the lens 16 and the distance L3 between the filter surface of the optical filter 17 and the center of the lens 19 are the thickness of the substrate of the optical filter 17, the thickness of the holder 18, and the like. Therefore, in reality, it cannot be made the same, and L3 is inevitably longer due to dimensional restrictions.
Therefore, it is necessary to shift the optical axis 34 of the lens 16 and the optical axis 35 of the lens 19 by a distance L5 as shown in FIG. By doing so, the positions of c and d on the lens 19 and the positions of a and b on the lens 16 can be made the same position with respect to the optical axes 34 and 35, respectively. Loss coupling can be realized. In this case, the position of the optical fiber 12 from the optical axis 34 and the position of the optical fiber 22 from the optical axis 35 are basically the same.

  According to the optical module described above, the sleeve 14 is used in the alignment fixing between the optical fiber holder 13 holding the optical fibers 11 and 12 and the holder 15 to which the lens 16 and the optical filter 17 are fixed. The optical fiber holder 13 is inserted into the sleeve 14 and positioned in the axial direction (Z direction) to be bonded and fixed, and has a flat surface (end face 15a) that can be adjusted in the direction perpendicular to the axis. The end face of the sleeve 14 is abutted against the holder 15, positioning in the in-plane direction (X, Y direction) is performed, and the contact surfaces of the holder 15 and the sleeve 14 are bonded and fixed to each other, whereby the optical fiber holder 13. And the holder 15 are aligned and fixed in three axial directions.

  The thickness of the adhesive 25 (see FIG. 2) existing between the sleeve 14 and the holder 15 can be suppressed to about 10 μm by an appropriate pressure contact force between the sleeve 14 and the holder 15 at the time of bonding and fixing. Since the shrinkage of the adhesive 25 almost acts in the Z direction, the positional deviation in the X and Y directions due to the curing shrinkage of the adhesive hardly occurs. Even if the optical fiber retainer 13 and the sleeve 14 are bonded and fixed, they are adjusted (corrected) when the sleeve 14 and the holder 15 are aligned even if they are displaced in the radial direction (X, Y direction). So there is no problem.

On the other hand, FIG. 4 shows an optical fiber 12 of light input from the optical fiber 11 when the optical fiber holder 13 holding the optical fibers 11 and 12 is shifted in the Z direction from the position aligned with the lens 16. The reflection coupling loss is shown in FIG. 1. Even if it is shifted by 1 μm, the loss is very small at 0.0014 dB, which is substantially negligible.
As described above, according to this example, the deterioration of the coupling efficiency due to the adhesive fixing after the alignment hardly occurs.
Further, although the thermal expansion coefficient of the adhesive depends on the type, for example, an epoxy resin adhesive is typically about 100 ppm / ° C., and the thickness of the adhesive layer is 10 μm as described above, If the temperature change is, for example, 50 ° C. at maximum, the change in the adhesive layer thickness is 0.05 μm. Although this change amount is a positional shift in the Z direction, as described above, the influence on the performance can be ignored, and thus an optical module excellent in temperature stability can be obtained.

Although the adhesive fixing between the sleeve 14 and the holder 15 has been described, the same applies to the adhesive fixing between the sleeve 20 and the holder 18 and the adhesive fixing between the holder 15 and the holder 18.
The optical module having the configuration shown in FIG. 1 requires an alignment jig (corresponding to the optical Assy 1) as a light source in alignment fixing of the optical assembly 2. In this case, alignment is performed. Since the accuracy of the jig becomes the alignment accuracy of the optical Assy 2 as it is, the alignment jig needs to be highly accurate, and periodic calibration and maintenance are required.

The optical module shown in FIG. 5 can solve this problem. In this example, an optical fiber 26 for alignment is added to the optical assembly 2 in the optical module shown in FIG. Yes.
The alignment optical fiber 26 has substantially the same dimensions as the optical fibers 11 and 12 held by the optical fiber holder 13 and is held by the optical fiber holder 27 in parallel with the optical fiber 22, that is, the optical fiber 22. , 26 and the optical fiber holder 27, the fiber Assy 2A 'is the same as the fiber Assy 1A.

The alignment fixing of the optical Assy 2 ′ including the fiber Assy 2A ′, the sleeve 20, and the lens Assy 2B can be performed in the same manner as the alignment fixing of the optical Assy 1 described above. In the alignment of the optical assembly 2 ′, light is incident on the optical fiber 26 from the light source, and an optical power meter for optical monitoring is connected to the optical fiber 22. In this example, the lens Assy 2B is fixed to a centering device in close contact with a reflector 28 as shown in FIG.
FIG. 6 is a light ray diagram in the case where the alignment light is incident on the optical fiber 26 and the optical Assy 2 'is aligned. In the figure, 41 indicates incident light and 42 indicates reflected light. The distance L6 between the center of the lens 19 and the reflecting surface of the reflecting plate 28 and the distance L7 between the center of the lens 19 and the end surface 27c of the optical fiber holder 27 are set to the same length as the focal length of the lens 19. .

According to the optical module including the optical Assy 2 'as described above, the alignment of the optical Assy 2' is extremely easy as compared with the optical module of FIG. The dummy reflector 28 is used simply in close contact with the surface 18b of the holder 18, so that there is no problem in accuracy. Even if the alignment light enters the optical fiber 22 and is monitored by the optical fiber 26, the same alignment can be performed.
The aligning optical fiber 26 becomes unnecessary after the alignment is completed. Whether to cut and remove or to leave as it is is determined according to the application. When cutting, it is necessary to perform terminal processing so that no return light is generated from the cut end face.

FIG. 7 shows the configuration of a TAP-PD (monitor module) for monitoring a part of light as another embodiment of the optical module according to the present invention. is doing. In the figure, reference numeral 29 denotes a light receiver. In this example, light from the optical fiber 11 is converted into parallel light by the lens 16 and enters the optical filter 17, and a part of the light passes through the optical filter 17 and is received. 29 is detected. Also in this example, the above-described adhesive fixing methods (1) to (3) can be applied in the alignment fixing of the optical assembly 1.
In the above-described embodiments, the lenses 16 and 19 are illustrated as ball lenses. However, the present invention is not limited to this, and the lens 16 and 19 have a function of converting light from an optical fiber into parallel light or condensing parallel light into the optical fiber. Any GRIN lens, aspherical lens, hemispherical lens, rod lens, or GI fiber may be used.

  Further, the lenses 16 and 19 may have different characteristics depending on the application, but in general, since the aperture angles to the optical fiber are the same, it is better to have the same characteristics (same focal length). Furthermore, when the lenses 16 and 19 are, for example, ball lenses, the same material and the same diameter are used, more excellent characteristics can be obtained as an optical module.

Sectional drawing which shows one Example of the optical module by this invention. The expanded sectional view of the optical Assy 1 in FIG. FIG. 2 is a ray diagram of the optical module shown in FIG. 1. The graph which shows the reflective coupling loss by the distance error between 2 core optical fibers and a lens. Sectional drawing which shows the Example which added the optical fiber for alignment with respect to the optical module shown in FIG. FIG. 6 is a light ray diagram when the optical Assy 2 ′ in the optical module shown in FIG. 5 is aligned. Sectional drawing which shows the other Example of the optical module by this invention. Sectional drawing which shows the example of a conventional structure of an optical module. The figure for demonstrating the position shift which arises by the hardening shrinkage | contraction of an adhesive agent in the optical module shown in FIG. The graph which shows the reflective coupling loss by the position shift of the optical axis with respect to the lens of a 2 core optical fiber at the orthogonal direction.

Claims (6)

The ends of the two optical fibers are arranged in parallel to each other, the light emitted from the end face of one of the optical fibers is transmitted through the lens and incident on the optical filter, and the reflected light reflected by the optical filter is again the lens. An optical module comprising at least an optical system that passes through and enters the end face of the other optical fiber,
The terminal is inserted and held in a cylindrical optical fiber holder whose optical axis and central axis are parallel,
The optical fiber retainer is inserted into a cylindrical sleeve that can be axially adjusted by inserting the optical fiber retainer, aligned in the axial direction, and the surfaces facing each other are bonded and fixed,
The lens and the optical filter are accommodated and fixed in the holder,
The holder end surface of the sleeve abuts, has a position adjustable plane perpendicular to the sleeve with respect to its axis, and the sleeve and the holder is to match the position in the vertical direction, those of each other An optical module characterized in that a contact surface is fixed by adhesion. The optical module according to claim 1,
An optical module, wherein at least one of the sleeve and the holder is made of a material that transmits light, and a photo-curing adhesive is used for the adhesive fixing of the sleeve and the holder. The optical module according to claim 2,
Adhesive with higher adhesive strength than that of the photo-curable adhesive is applied and fixed to the boundary between both members on the outer periphery of the adhesive surface of the sleeve and the holder, which is fixed by using the photo-curable adhesive. An optical module characterized by being reinforced.   The optical module according to any one of claims 1 to 3,
  On the side of the optical filter opposite to the side where the ends of the two optical fibers are arranged, the transmitted light that has passed through the filter passes through another lens and enters the end face of the other optical fiber. Further comprising an optical system,
  The other end of the optical fiber is arranged in parallel with another end of the optical fiber for alignment, and the other end of the cylindrical shape whose optical axis and the central axis are parallel to each other is arranged. Inserted and held in an optical fiber holder,
  The other fiber optic retainer is inserted into another sleeve of the cylindrical body that is axially adjustable by inserting the other fiber optic retainer and is axially aligned and paired with each other. The contact surface is adhesively fixed,
  The other lens is attached to another holder,
  The other holder is bonded and fixed to the surface of the holder opposite to the plane against which the sleeve is abutted, and the other sleeve is fixed to the opposite side of the surface to which the holder is bonded and fixed. The end face is abutted, and the sleeve has a plane that can be vertically adjusted with respect to the axis, and the other sleeve and the other holder are aligned in the vertical direction so that they contact each other. An optical module characterized in that a contact surface is fixed by adhesion.   A method for producing an optical module according to claim 1,
  The optical fiber holder holding the ends of the two optical fibers is inserted into the sleeve, and is disposed immediately above the holder that accommodates and fixes the lens and the optical filter, and the end surface of the sleeve is In the free fall state, the light from the light source is incident on one of the two optical fibers so as to be in contact with the plane of the holder, and an optical power meter for optical monitoring is connected to the other. Fixing the sleeve and the optical fiber holder together with an adhesive at the position of the optical fiber holder where the indication is maximized;
  A step of abutting the sleeve and the optical fiber holder fixed to each other with the adhesive against the flat surface of the holder and realigning, and then fixing the sleeve and the holder to each other with an adhesive. An optical module manufacturing method characterized by the above.   A method for producing the optical module according to claim 4,
  The other optical fiber holder holding the other optical fiber end and the alignment optical fiber end is inserted into the other sleeve, and a reflective plate is placed underneath so as to adhere to the sleeve. The other lens is fixed immediately above the other holder, and the end surface of the other sleeve is in a free-falling state so as to be in contact with the plane of the other holder. The light from the light source is incident on one of the other optical fiber and the alignment optical fiber, and an optical power meter for optical monitoring is connected to the other. An optical module comprising the step of fixing the other sleeve and the other optical fiber holder to each other at the position of the another optical fiber holder. Manufacturing method.

Images