The present invention relates to an optical waveguide module, particularly to an optical waveguide module with an optical waveguide substrate in which an optical circuit is formed in a resin substrate, and the optical waveguide module is used in an optical communication network.
An optical waveguide bare module is used in the fields of the optical communication and the like. In the optical waveguide bare module, an optical waveguide substrate in which an optical circuit is formed in a substrate and an optical fiber array in which one or more optical fibers are fixed are bonded to each other while optical axes of the optical waveguide substrate and optical fiber array are aligned. The optical waveguide bare module is accommodated in a package to prevent shock from the outside. In the conventional optical waveguide module, as described in Patent Document 1 (Japanese Patent Publication Laid-Open No. 2003-207658), the optical waveguide bare module is accommodated in the package which is vertically separated along an axial direction of the optical fiber. In such structures, there is a limit to suppression of invasion of moisture from a bonded surface at which an upper portion and a lower portion of the package are bonded, and unfortunately deterioration is generated in a bonding agent of the optical waveguide bare module inside the package and a resin portion such as the optical waveguide substrate.
In Patent Document 2 (Japanese Patent Publication Laid-Open No. 2002-23000), a cylindrical package is used to accommodated the optical waveguide bare module therein, largely-opened end portions of the package are sealed with resins to block the inside of the package from the outside. In Patent Document 3 (Japanese Patent Publication Laid-Open No. 2001-51149), the optical waveguide bare module formed by bonding semicircular cylindrical bases is accommodated in the cylindrical base, the cylindrical base coated with a resin foaming material is accommodated in a cylindrical package, and both ends of the package are sealed with resins. However, in the structures disclosed in Patent Documents 2 and 3, because the whole surfaces of both the ends of the cylindrical package are sealed with the resins, similarly to Patent Document 1, it is difficult to completely suppress the invasion of the moisture into the package.
Patent Document 1: Japanese Patent Publication Laid-Open No. 2003-207658
Patent Document 2: Japanese Patent Publication Laid-Open No. 2002-23000
Patent Document 3: Japanese Patent Publication Laid-Open No. 2001-51149
In view of the foregoing, an object of the invention is to provide an optical waveguide module having high reliability against the moisture by a structure in which the moisture hardly intrudes into the case accommodating the optical waveguide.
In accordance with an aspect of the invention, an optical waveguide module includes an optical waveguide bare module including an optical waveguide substrate in which an optical circuit is formed in a substrate and an optical fiber array in which one or plural optical fibers are arrayed and fixed; a hollow and cylindrical case in which the optical waveguide bare module is accommodated; and blocks which are attached to both ends of the case to seal a hollow portion of the case, and the optical waveguide module is characterized in that the optical waveguide bare module is disposed in the case and the case is sealed in an airtight manner by inserting the blocks into both the ends of the case.
According to the optical waveguide module of the invention, the optical waveguide bare module is disposed in the case sealed in the airtight manner. Therefore, the optical waveguide bare module hardly contact the moisture, and the deterioration caused by the contact with the moisture can be prevented.
In the optical waveguide module according to the aspect of the invention, preferably an inside of the case in which the blocks are attached to both the ends thereof is sealed in a reduced-pressure state. According to the aspect of the present invention, because the pressure is reduced inside the case, a force is applied to the block toward a direction in which the air is sucked in the case, and the block is hardly extruded outward due to the reduced pressure of the air enclosed in the case even if a temperature rises slightly. The case may be filled with the dried air or the case may be filled with dried nitrogen gas or inert gas.
In the optical waveguide module according to the aspect of the invention, preferably an air pressure in the case sealed by attaching the blocks to both the ends thereof is not more than one atmosphere. According to the aspect of the present invention, because the inside of the case is kept at a pressure not more than one atmosphere, the block is hardly extruded outward due to the reduced pressure of the air enclosed in the case. The case may be filled with the dried air or the case may be filled with dried nitrogen gas or inert gas.
In the optical waveguide module according to the aspect of the invention, preferably the optical waveguide bare module is accommodated in the case along with the bare module support member while fixed to a bare module support member. According to the aspect of the present invention, because the optical waveguide bare module is reinforced by fixing the optical waveguide bare module to the bare module protective member, the optical waveguide bare module is hardly broken during handling such as the insertion of the optical waveguide bare module into the case.
In the optical waveguide module according to the aspect of the invention, preferably both ends of the bare module support member are bent to form a surface perpendicular to a lengthwise direction of the case. According to the aspect of the invention, because the block is stopped while abutting the portion in which both the ends of the bare module protective member are bent, the block is not brought closer to the optical waveguide bare module from the bent portion of the bare module protective member, and the block is not excessively put in the case to break the optical waveguide bare module. Additionally, because a predetermined distance can be provided between the optical waveguide bare module and the block, the optical fiber breakage caused by forced bending is not generated even if misalignment is generated between the optical waveguide bare module and the optical fiber hole of the block.
In the optical waveguide module according to the aspect of the invention, preferably a projection is provided at a position where the block of the case is attached in an inner surface of the case. In the optical waveguide module according to the aspect of the invention, preferably in a portion in which a step is provided in an outer peripheral surface of the block so as to be inserted into the case, a sectional area of an outside portion is smaller than a sectional area of an inside portion. According to these aspects of the present invention, because a predetermined gap can be formed between the case and the block, the bonding agent or resin can be caused to flow into the gap even if a spherical hardening agent or filler or the like is mixed in the bonding agent or resin or the like.
In the optical waveguide module according to the aspect of the invention, preferably an optical fiber hole is made in the block to draw an optical fiber to an outside, and a gap between the case and the block and the optical fiber hole in the block are filled with a bonding agent or a resin having low moisture permeability and the bonding agent or resin is hardened. In the optical waveguide module according to the aspect of the invention, preferably an evacuation hole is provided in the block to evacuate air in the case. According to these aspects of the present invention, because the fiber hole dedicated to the insertion of the optical fiber is made, the optical fiber connected to the optical waveguide bare module can be drawn to the outside. Because the gap connecting the inside of the case and the outside is closed by filling the gap with the bonding agent or resin having low moisture permeability, the moisture hardly invades into the case from the gap. Because the evacuation hole is made independently of the fiber hole, the moisture in the case can be released to the outside of the case through the evacuation hole by baking or the like after the case and the block are fixed and after the block and the optical fiber are fixed.
In the optical waveguide module according to the aspect of the invention, preferably the block is divided into two. According to the aspect of the present invention, because the two divided parts are bonded to form the block, when the two divided parts are combined to make the optical fiber hole, the trouble of inserting the long optical fiber into the block is saved.
In the optical waveguide module according to the aspect of the invention, preferably the evacuation hole is sealed by covering an opening thereof with a plate. In the optical waveguide module according to the aspect of the invention, preferably the evacuation hole is sealed by closing an opening thereof with a ball whose diameter is larger than the opening. According to these aspects of the present invention, because the evacuation hole is closed by the plate of ball, the moisture hardly invades into the case when compared with the case in which evacuation hole is simply closed by the resin or bonding agent. Particularly, in the case of the use of the ball, the ball is sucked into a flow of the bonding agent or resin with which the evacuation hole is filled, and the ball rolls automatically into the position where the evacuation hole is closed by the ball, so that the evacuation hole can easily be sealed to shorten a time necessary to the process.
In the optical waveguide module according to the aspect of the invention, preferably the block is made of a material having low moisture permeability. In the optical waveguide module according to the aspect of the invention, preferably the case is made of a material having low moisture permeability. According to these aspects of the present invention, because the block and the case are made of the materials having the low moisture permeability, the moisture does not invade into the case through the block and case. A metal and a ceramic can be used as the material having the low moisture permeability.
In the optical waveguide module according to the aspect of the invention, preferably a sheet absorbing moisture is provided around the optical waveguide bare module. Accordingly, because the sheet can absorb the moisture invading into the case from the outside, the optical waveguide bare module hardly contacts the moisture.
In the optical waveguide module according to the aspect of the invention, preferably an optical fiber protective member made of an elastic material is attached to an end portion of the block. According to the aspect of the present invention, the optical fiber protective members are attached to both the ends of the case to prevent the bending over the limit of the optical fiber drawn to the outside of the case.
In the optical waveguide module according to the aspect of the invention, preferably the optical fiber protective member is attached to the block by fitting a protrusion provided in the block into a recess provided in the optical fiber protective member. According to the aspect of the present invention, the optical fiber protective member is attached only by fitting the protrusion provided in the block into the recess provided in the optical fiber protective member, so that the alignment can easily be performed between the block and the optical fiber protective member. According to these aspect of the present invention, because the protrusion of the block and the recess of the optical fiber protective member are fitted and bonded, the block and the optical fiber protective member are fixed more strongly compared with the case in which flat surfaces of the block and the optical fiber protective member are bonded to each other.
The constituents described in the invention can arbitrarily be combined as much as possible.
a) and 3(b) are enlarged top views showing end portions of the optical waveguide bare module of
a) and 4(b) are views showing the optical waveguide module of
a) is a side view of a case.
a) is a side view showing a sealing block used in the optical waveguide module of the first embodiment.
a) is a side view showing a sealing block different from the sealing block used in the optical waveguide module of the first embodiment.
a) is a side view showing a rubber boot used in the optical waveguide module of the first embodiment.
a) is a side view showing a rubber boot different from the rubber boot used in the optical waveguide module of the first embodiment.
a) is a successive view of
a) is a side view showing a sealing block used in the optical waveguide module of the third embodiment.
a) is a side view showing a sealing block different from the sealing block of
a) and 22(b) are views for explaining a method of sealing an evacuation hole of a sealing block of a fourth embodiment.
a) is a side view showing a sealing block of a fifth embodiment.
Embodiments of the invention will be described in detail with reference to the drawings. However, obviously the invention is not limited to the following embodiments.
a) and 3(b) are top views showing neighborhoods of end portions of the optical waveguide bare module 11 in which the hygroscopic sheet 24 is detached from the top surface respectively.
a) is a side view of the case 12, and
The sealing blocks 13a and 13b are made of a material, such as a metal and a dense ceramic, which has extremely-low moisture permeability. The sealing block 13a attached onto the side of the optical fiber array 22a differs from the sealing block 13b attached onto the side of the optical fiber array 22b in the shape.
The optical fiber protective member, i.e., the rubber boots 14a and 14b are used to prevent the breakage of the optical fiber 23 drawn through the sealing blocks 13a and 13b. The sealing blocks 13a and 13b are broken by bending the sealing blocks 13a and 13b at a sharp angle. Similarly to the sealing blocks 13a and 13b, the rubber boot 14a attached onto the side of the optical fiber array 22a differs from the rubber boot 14b attached onto the side of the optical fiber array 22b in the shape.
Alternatively, the case is formed longer than the length of the case 12, the sealing blocks 13a and 13b are put in the case 12, and the rubber boots 14a and 14b may be inserted into the end portions of the case 12.
A process of assembling the optical waveguide module 1 will be described with reference to
As shown in
After hardening the sealing agent 35, the fiber holes 42 of the sealing blocks 13a and 13b are filled with the sealing agent 35 again, and the sealing agent 35 is hardened. The sealing blocks 13a and 13b and the optical fiber 23 are fixed while the fiber holes 42 are sealed.
Then, the case 12 is heated to 90° C. in a vacuum atmosphere not more than 133 Pa to perform vacuum baking for about one hour, and a water content in the case 12 is released to the outside of the case 12. A time necessary to sufficiently suck a bonding agent 37 in the evacuation hole 43 of the case 12 is previously determined by investigating conditions, and the case 12 is gradually cooled for the time to fill the bonding agent 37 with the evacuation hole 43. Because the bonding agent is applied while the case 12 is gradually cooled, the inner pressure of the case 12 becomes the reduced-pressure atmosphere compared with the outer pressure of the surround of the case, the applied bonding agent is sucked to fill the entire longitudinal direction of the evacuation hole 43 with the bonding agent. The bonding agent 37 is an ordinary-temperature hardening type bonding agent different from the bonding agent 36.
A bonding agent sucking mechanism will be described below. As shown in
In the optical waveguide module 1 produced in the above-described way, the surround of the optical waveguide bare module 11 is substantially covered with the case 12 and sealing blocks 13a and 13b, and the gap is filled with the sealing agent 35 having the low moisture permeability, the hygroscopic sheet 24 is bonded to the surround of the optical waveguide bare module 11 using the bonding agent 36, and the evacuation hole 43 is sealed with the bonding agent 37. Therefore, the moisture hardly invades into the case 12, and the optical waveguide bare module 11 is not deteriorated by the moisture.
After the heating is performed at the temperature of 85° C. for about one hour, a leak test may be performed to confirm whether or not the inside of the case 12 is sufficiently sealed from the outside. The leak test can distinguish the sufficiently-sealed optical waveguide module 1 from the insufficiently-sealed optical waveguide module 1.
In the optical waveguide module 1 of the first embodiment, because only the optical waveguide substrate 21 and the optical fiber arrays 22a and 22b are bonded in the optical waveguide bare module 11, the optical waveguide bare module 11 is possibly broken due to the impact during the handling such as the insertion of the optical waveguide bare module 11 into the case 12. In an optical waveguide module 2 according to a second embodiment of the invention, the optical waveguide bare module 11 is reinforced by fixing the optical waveguide bare module 11 onto a bare module support member, i.e., an inner frame 61, thereby facilitating the handling of the optical waveguide bare module 11.
As shown in
As shown in
The vertical misalignment is hardly generated because a gap is hardly formed between the front end of the guide portion 63 and the upper surface of the hollow portion 33 of the case 12. The front end of the guide portion 63 is bent toward the side of the optical waveguide bare module 11, and the optical waveguide bare module 11 is hardly hooked in the entrance of the case 12 or the projection 34 when the optical waveguide bare module 11 is inserted in the case 12. The shape of the front end of the guide portion 63 may be designed such that the trouble is not generated in the arrangement or insertion of the optical fiber 23 in the case 12.
In the optical waveguide module 1 of the first embodiment, the projections 34 are provided in the case 12 to cause the sealing agent 35 to flow easily into the gap between the case 12 and the sealing blocks 13a and 13b. However, because the projections 34 are projected toward the inside of the case 12, sometimes the projections 34 block the insertion of the optical waveguide bare module 11 into the case 12. An optical waveguide module 3 according to a third embodiment of the invention is proposed to solve the problem. In the optical waveguide module 3, steps (hereinafter referred to as step portions 65) are provided around the sealing blocks 16a and 16b such that each outside half of the sealing blocks 16a and 16b are formed slightly thinner than each inside half of the sealing blocks 16a and 16b. This enables a gap 66 to be formed between the sealing blocks 16a and 16b and a case 17 to easily pour the sealing agent 35.
As shown in
Thus, the step portions 65 are provided not on the side of the case 17, but in the sealing blocks 16a and 16b, and the gap 66 for pouring the seal agent 35 is formed between the case 17 and the sealing blocks 16a and 16b. Therefore, it is not necessary to form the projection 34 in the case 17, and the optical waveguide bare module 11 is not hooked in the projection 34 when inserted into the case 17. Accordingly the efficiency can be improved in the assembly.
In the process of assembling the optical waveguide module 1 of the first embodiment, for the sealing of the evacuation hole 43 in the sealing block 13a, as shown in
a) and 22(b) show sealing structures of the evacuation hole 43 of the sealing block 18a respectively. The evacuation hole 43 of the sealing block 18a is configured by combining two sealing holes 68a and 68b having different opening diameters. The sealing hole 68a is opened from the surface of the sealing block 18a orientated toward the outside of the case 12, and the sealing hole 68b is opened from the surface of the sealing block 18a orientated toward the inside of the case 12. The center axes of the sealing hole 68a and sealing hole 68b are aligned with each other, and the sealing hole 68a and the sealing hole 68b are continuously made in the sealing block 18a. The sealing hole 68b is larger than the sealing hole 68a in the opening diameter, a sphere (hereinafter referred to as sealing ball 69) having an opening diameter larger than that of the sealing hole 68b is inserted in the sealing hole 68a, and the sealing ball 69 is bonded using the bonding agent 37, whereby the sealing hole 68b is closed to block the case 12 such that the air does not invade into the case 12. The sealing ball 69 is made of a material such as the spherical metal or ceramic having the extremely low moisture permeability.
A method of sealing an evacuation hole 43 will be described with reference to
In the fourth embodiment, the bonding agent 37 is previously applied to the sealing ball 69 in order to improve the wettability with the bonding agent 37 with which the sealing hole 68b is filled. However, the bonding agent 37 is not previously applied to the sealing ball 69 in the case where the reliability can particularly be ensured. In order to improve the wettability between the sealing ball 69 and the bonding agent 37, physical or chemical treatment may previously be performed to the surface of the sealing ball 69.
In the process of assembling the optical waveguide module 1 of the first embodiment, when the long optical fiber 23 is connected to the optical waveguide bare module 11, it is necessary that the optical fiber 23 be inserted into each fiber hole 42 of the sealing blocks 13a and 13b from the end portion of the optical fiber 23, which sometimes takes a lot of trouble. A sealing block 19 according to a fifth embodiment of the invention is proposed to solve the problem to facilitate the installation of the sealing block. The sealing block 19 which can be replaced by the sealing block 13a will be described below.
a) is a side view showing the sealing block 19, and
Accordingly, even if the long optical fiber 23 is connected to the optical waveguide bare module 11, the trouble of inserting the optical fiber 23 into the sealing block 1 from the front end of the optical fiber 23 to move the optical fiber 23 to the neighborhood of the optical waveguide bare module 11 can be eliminated when the sealing block 19 is assembled near the optical waveguide bare module 11 (or case 12).
Number | Date | Country | Kind |
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2005-233757 | Aug 2005 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2006/315513 | 8/4/2006 | WO | 00 | 2/8/2008 |