JP2004219766A - Optical communication module, optical communication component and its manufacture method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication module which can be simply assembled by solving such a problem in the conventional optical communication module that the adjustment of optical axis is difficult and the assembly accuracy can not be enhanced. <P>SOLUTION: In the optical communication module, at least a first optical member, a second optical member and a third optical member are arranged in this order on an optical path of optical communication and, therein, the positional alignment is performed on the basis of the first optical member. The third optical member is not coupled to the second optical member but is positioned by directly being coupled to the first optical member as reference. The positioning and optical axis alignment can be simply performed, the positional deviation is not integrated and the deviation of optical axis as the total module can be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical communication component used for optical communication, an optical communication module, and a method for manufacturing the same.
[0002]
In data communication using an optical fiber, it is necessary to transmit and receive a large amount of information at high speed.
[0003]
In recent years, a new technology called optical multiplex communication has appeared, and it is possible to further increase the speed and increase the capacity. Under such circumstances, the demand for optical communication components is increasing more and more, and cost reduction and improvement in reliability have been issues for component suppliers.
[0004]
[Prior art]
Heretofore, in the optical communication component mounting module, when assembling the optical components in combination, the optical axes of the optical components have been adjusted and aligned one by one and fixed with resin or metal. However, in this method, the adjustment takes time, there is a problem in manufacturing efficiency, and it has been a factor that an inexpensive product cannot be supplied. This is because high precision is required particularly for positioning the optical fiber and optical components such as lenses connected thereto. For example, in a wavelength division multiplexing transmission system, a so-called WDM thin film filter module for selectively extracting only a signal of a specific wavelength has a structure having three terminals of incident light, transmitted light, and reflected light. As a typical example, this module includes an optical fiber 16a for incident light, an optical fiber 16b for reflected light, a dual capillary 14, a first collimating lens 11, a thin film filter element 13, a second collimating lens 12, as shown in FIG. It is composed of optical components of a single capillary 15 and an optical fiber 16c for transmitted light. The optical axis of each of these components is adjusted and aligned, fixed with an adhesive or the like, and sealed in a metal tube or the like. In the case of such a structure, the accuracy of aligning the center of the core of the optical fiber inserted into the capillary with the position of the focal point of the collimating lens needs to be at least ± 5 μm as a typical value, and the optical axis must be aligned. The degree of parallelism was also required, which required a very advanced position and optical axis adjustment process.
[0005]
As means for solving the above-mentioned problem of the optical axis adjustment, Japanese Patent Application Laid-Open No. H11-163,098 is known. Patent Literature 1 discloses a method of positioning a plurality of lenses in a lens barrel.
[0006]
In the state where the first lens is in contact with the receiving surface of the lens barrel and positioned in the optical axis direction, the second lens in the next stage is in contact with the first lens to perform positioning in the optical axis direction. .
[0007]
Further, in FIG. 2 of Document 1, the third lens is positioned by bringing the third lens into contact with the second lens. Patent Literature 1 describes that the position adjustment of a plurality of lenses can be easily performed by repeating this process.
[0008]
[Patent Document 1]
JP-A-2002-286987
[Problems to be solved by the invention]
However, in the method of Patent Document 1, for example, in FIG. 2 of Document 1, the optical axis shifts at the contact surface between lens 1 and lens 2 and the contact surface between lens 2 and lens 3, respectively. The deviation is expected to increase as the number of lenses increases as they are integrated. As described above, in an optical communication module, high precision is required for optical axis alignment, and it is difficult to obtain that precision by the method of Patent Document 1.
[0010]
Further, the optical components arranged on the optical axis disclosed in Patent Document 1 are only lenses. Unlike a lens, a thin film filter or the like sometimes has thickness unevenness caused by processing accuracy (cutting out the filter). Therefore, in a WDM three-terminal filter module or the like in which a thin film filter is sandwiched between two lenses, it is impossible to obtain the required precision of optical axis alignment using the method of Patent Document 1.
[0011]
The problems of the prior art as described above are that, since the optical components are arranged and joined in the order in which they are arranged, the thickness unevenness of the adhesive between the optical components and the processing accuracy of the optical components themselves. In this case, the size unevenness due to the above is accumulated, and the deviation of the position and the optical axis between the optical components that are far apart, such as the optical components at both ends of the module, in particular, is increased. In the example of the WDM three-terminal filter module, when assembling the optical components, if the first collimating lens, the thin-film filter, and the second collimating lens are adhered to each other in this order, the adhering portions become two places, and the adhesive Since the thickness unevenness is added and the thickness unevenness due to the processing accuracy of the thin film filter is added, the parallelism and the vertical alignment of the optical axes of the two collimating lenses are easily shifted and adjustment can be easily performed. Did not.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems that the optical axis adjustment of the conventional optical communication module has difficulty in adjusting the optical axis and the assembling accuracy cannot be increased, and to provide an optical communication module that can be easily assembled. And
[0013]
[Means for Solving the Problems]
The present invention is an optical communication module, wherein at least a first optical member, a second optical member, and a third optical member are arranged in this order on an optical path of optical communication, and the third optical member is The present invention relates to an optical communication module that is joined to a first optical member.
[0014]
In the present invention, the first optical member is used as a reference for positioning. The third optical member is not bonded to the second optical member, but is positioned by directly bonding to the reference first optical member.
[0015]
An example of a WDM three-terminal thin film filter module will be described. In this module, as an application of the present invention, the first collimating lens is referred to as a “first optical member” serving as a reference for positioning, and the second collimating lens is referred to as a “third optical member”. The first collimator lens and the second collimator lens have a joint 21a as illustrated in FIG. Then, these collimating lenses are directly joined with the contact surfaces 21c of the joining portion 21a facing each other. Thus, the two lenses are positioned. At least the second collimating lens is not directly bonded to the thin film filter. With such a configuration, the first collimating lens and the second collimating lens can mutually adjust the position and parallelism of the optical axis only with the processing accuracy of the two.
[0016]
As a procedure of assembling as a module, first, the first collimating lens and the second collimating lens are combined by bonding their contact portions. The abutment surface of the joint is molded or processed so as to have a plane perpendicular to the optical axis of each lens with high precision. Then, the lens position is adjusted so that the respective optical axes coincide. Next, a thin-film filter is arranged between these two lenses, the degree of parallelism of the filter surface with respect to the optical axis is controlled so as to obtain predetermined characteristics, and the film is fixed with an adhesive or the like. With such steps, a simple assembling step can be realized.
[0017]
As described above, according to the present invention, positioning and optical axis alignment can be easily performed only by bringing the third optical member into contact with the first optical member. In addition, since only the “first optical member” is used as the optical member serving as a reference for alignment, positional deviations are not accumulated, and optical axis deviations in the entire module can be reduced.
Hereinafter, the present invention will be described in detail.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An example in which the present invention is applied to a three-terminal filter module for WDM as a first embodiment will be described with reference to FIG.
[0019]
The three-terminal filter module for WDM includes an optical fiber 16a for incident light, an optical fiber 16c for transmitted light, an optical fiber 16b for reflected light, a first collimating lens 11, a second collimating lens 12, a thin film filter 13, a dual capillary 14, and a single capillary. It consists of 15 parts.
[0020]
A plurality of light beams having different wavelengths are multiplexed and transmitted to the optical fiber for incident light 16a. The light emitted from the optical fiber for incident light 16a enters the first collimating lens 11. The first collimating lens 11 has a function of converting light emitted from the incident light optical fiber 16a into parallel light. This parallel light enters the thin film filter 13. The filter transmits only light (λm) having a predetermined wavelength, and the light is incident on the second collimating lens 12. Other light is reflected and returns to the first collimating lens 11. The light (λm) transmitted through the second collimating lens 12 is collected on the end face of the transmitted light fiber 16c and guided into the fiber. The light reflected by the thin-film filter 13 is condensed by the first collimator lens 11 on the end face of the reflected light optical fiber 16b, and is introduced into the fiber.
[0021]
The dual capillary 14 is a component that holds two optical fibers, an optical fiber 16a for incident light and an optical fiber 16b for reflected light. The single capillary 15 is a component that holds the transmitted light optical fiber 16c. Each capillary is made of a known member such as zirconia or quartz.
[0022]
In this embodiment, a sleeve 31 having a shape as shown in FIG. 3 is used to load these components. The sleeve 31 was formed from a stainless steel tubular body, and had a structure that could be assembled as described below. The sleeve 31 is provided with a slit 31a for passing an adjustment arm described later. In addition, a hole 31b for filling the adhesive and a hole 31c for loading the thin film filter were provided.
[0023]
FIG. 2 shows a typical shape of the first collimating lens and the second collimating lens.
[0024]
In the first collimating lens and the second collimating lens, a joint 21a to which the present invention is applied is provided at the outer edge of the lens. This type of lens will be referred to as a joint-integrated lens 21. Due to this joint portion, the first collimator lens as the first optical component is directly joined to the second collimator lens as the third optical component without passing through the thin film filter as the second optical component. Can be. The joining portion 21a serves as a positioning means, and by joining the contact surfaces 21c substantially at the distal ends thereof to each other, a part of the assembly and the shaft adjustment is completed. The above-mentioned lens was formed by heating the optical glass and pressing it with a mold, and the lens body and the joint were each integrally formed.
[0025]
The mold was designed and manufactured so that each of the contact surfaces 21c of the joints could form a plane perpendicular to the optical axis of the collimator lens with high accuracy. As a typical value, it is preferable to manufacture it within a range of 90 ± 0.5 degrees with respect to the optical axis.
[0026]
Further, the center distance between the first collimating lens and the opposing second collimating lens can be defined by the length of each of the joints 21a.
[0027]
Next, a process of assembling the optical components of the present invention to configure a WDM three-terminal filter module will be described.
[0028]
In the first stage, positioning, optical axis adjustment, and fixing are performed so that the four members of the optical fiber for incident light, the first collimating lens, the second collimating lens, and the optical fiber for transmitted light are coupled with low loss.
[0029]
First, as shown in FIG. 4, the optical fiber for incident light 16a and the optical fiber for reflected light 16b are inserted into the dual capillary 14, fixed with an adhesive or the like, and the end face of the fiber is polished together with the end face 44 of the capillary. An anti-reflection film 45 is also formed on the surface of the entire surface of the capillary in a vacuum. As the antireflection film, a thin film having a known configuration may be used. Further, the optical fiber for transmitted light is inserted into a single capillary and fixed with an adhesive or the like, and the end face is polished and an antireflection film is formed in the same manner.
[0030]
Next, as shown in FIG. 5, the adjusting arm 52 is attached to each of the dual capillary and the single capillary subjected to the optical fiber connection processing, the first collimating lens, and the second collimating lens. The adjustment arm is held by a goniometer or the like to adjust the position and angle of each optical component from the outside.
Then, adjustment of the dual capillary 14 and the first collimating lens 11 is performed.
[0031]
The adjustment arms 52a and 52b attached to the respective optical components are held by a goniometer (not shown), and the two optical components are opposed to each other. Then, test parallel light having a predetermined wavelength is incident from the first collimating lens 11 side. The goniometer is adjusted so that the light beam condensed by the first collimating lens 11 is condensed on the fiber end face of the dual capillary 14 for the incident light and introduced into the fiber. The light beam traveling backward through the incident light fiber is monitored, and the position and the optical axis are adjusted so that the test parallel light propagates with the lowest loss. (First adjustment stage)
[0032]
Further, the position and the optical axis of the single capillary to which the transmitted light fiber is connected and the second collimating lens are similarly adjusted. (Second adjustment stage)
[0033]
The above-described first adjustment stage and second adjustment stage are configured such that each adjustment stage can be moved together with the goniometer in a state where independent adjustment has been completed. Then, as shown in FIG. 6, the two sets of optical components ([dual capillary + first collimating lens] and [second collimating lens and single capillary]) are kept adjusted from both ends of the sleeve, respectively. Insert inside the sleeve. At this time, the adjustment arm attached to each optical component has a form extending from the inside of the sleeve to the outside through the slit.
[0034]
Then, inside the sleeve, the contact surface of the joint of the first collimator lens on the first adjustment stage and the contact surface of the joint of the second collimator lens on the second adjustment stage are joined to each other. The first and second adjustment stages are moved for positioning.
[0035]
The parallelism of the optical axes of the first collimator lens and the second collimator lens is ensured only by joining the joining portions. In this state, test light is incident from the incident light fiber, and light emitted from the transmitted light fiber is monitored. Then, the position of the second adjustment stage with respect to the first adjustment stage is adjusted in the XY plane shown in FIG. 6 so that the test light has the lowest loss. At this time, if a pseudo substrate having the same refractive index as that of the substrate of the filter is arranged at the position where the thin film filter is installed, more accurate adjustment can be performed.
[0036]
After the adjustment as described above, an epoxy adhesive or the like is filled from the adhesive injection hole processed into the sleeve and cured. If necessary, the composition can be cured while heating.
During this time, it is more effective to monitor the test light and keep following the low loss state.
[0037]
Through the above steps, the adjustment and assembling such that the four members of the incident light fiber, the first collimating lens, the second collimating lens, and the transmitted light fiber are coupled with low loss is completed.
[0038]
Next, a membrane filter is loaded. As shown in FIG. 6, an adjusting arm is also attached to the membrane filter. Then, the membrane filter is loaded through the hole for loading the membrane filter of the sleeve. In this state, test light is introduced from the incident filter, and transmitted light and reflected light are monitored and each characteristic (center wavelength, insertion loss, transmission band ripple, pass band width, stop band width, etc.) meets the specifications. Adjust the angle and position. Since the reflection angle also changes, the reflection light loss from the reflected light optical fiber is also adjusted to be the lowest.
[0039]
After the adjustment is completed, an epoxy adhesive or the like is filled from the adhesive injection hole formed in the sleeve, and the film is cured while heating as necessary to fix the thin film filter. During this time, it is more effective to monitor the test light and keep following the low loss state.
[0040]
When the adhesive is completely cured, the adjustment arms attached to each optical component are removed or cut.
[0041]
Through the steps described above, the adjustment and assembly of the WDM three-terminal filter module using the optical component of the present invention is completed. FIG. 7 shows a cross-sectional view of the WDM three-terminal filter module according to the present invention that has been assembled. This schematically shows a state where the center of the module is cut on the XZ plane shown in FIG.
[0042]
By adopting the above configuration, the positioning and the optical axis adjustment work can be simplified only by joining the joint-integrated lenses in opposition.
[0043]
The sleeve shape can be arbitrarily configured according to the completed form of the module, but in the present embodiment, a cylindrical sleeve is used for the cylindrical optical component. The inner diameter of the sleeve is substantially the same as the diameter of each optical component. By adopting this structure, the optical axis of each optical component such as a collimator lens is positioned to some extent at the time of loading with appropriate accuracy by designing the outer diameter of the optical component and the inner diameter of the sleeve.
[0044]
In each of the embodiments described above, the modules using substantially cylindrical lenses, capillaries, cylindrical sleeves, and the like have been described. However, as long as they perform the same function, they are not limited to these shapes. Needless to say, it is not.
[0045]
Further, in the present embodiment, the metal sleeve is exemplified, but the metal sleeve is constituted by using a transparent member such as quartz glass, and by using an ultraviolet curing resin as the adhesive, after filling the adhesive in the bonding step, It is also effective to irradiate ultraviolet rays of the corresponding wavelength to cure.
[0046]
In this embodiment, a so-called aspherical lens having a curved surface having different curvatures at a peripheral portion and a central portion is used. However, the present invention is not limited to this, and can be applied to lenses of any shape. As a constituent material of the lens, optical glass (for example, quartz glass, borosilicate glass with material code BK-7, etc.) is used, but transparent resin (for example, epoxy, etc.) is also suitable for molding. I have.
[0047]
As the thin film filter, a so-called thin film filter element in which a dielectric thin film was laminated in multiple layers on a glass substrate by a process such as vacuum deposition was used. The production method is described in "All-dielectric Fabry-Perot etalon" (having a high refractive index with an optical path length of λ / 4) described in "Optical Thin Film" (translated by HA Macleod, translated by Shigetaro Ogura and published by Nikkan Kogyo Shimbun). A plurality of mirror layers each including a pair of the layer 8 and the low refractive index layer 9 are stacked, and a spacer layer 10 having an optical path length that is an integral multiple of λ / 2 is provided thereon, and the mirror layer is inverted thereon. (Having a basic structure in which the layers are laminated) are stacked with a bonding layer interposed therebetween, and manufactured using a known technique described in the above-mentioned literature and the like.
[0048]
The shape of the joining portion can take various forms so that positioning and optical axis adjustment are easy.
[0049]
(Example 2)
As a second embodiment of the present invention, an optical communication module having a structure in which a contact surface has a step as shown in FIG. 8 will be described.
[0050]
As in the case of the first embodiment, the incident optical fiber, the reflecting optical fiber, the dual capillary which is a member for holding the two optical fibers, and the first part provided with the joint according to the present invention are provided as in the first embodiment. A collimating lens, a thin film filter for WDM, and a lens for converging transmitted light, the second collimating lens being provided with a joint according to the present invention, and a transmission optical fiber.
[0051]
The difference from the first embodiment is that a step is formed on the contact surface of the joint. A convex step 81 was provided at the joint of the first collimating lens. Further, a step 82 having a shape for receiving the second collimating lens was provided at the joint portion of the second collimating lens. Like the first embodiment, the angle of the contact surface was made with a high accuracy of 90 ± 0.5 degrees with respect to the optical axis of each collimating lens.
[0052]
These two are combined and joined. According to this configuration, in addition to being able to easily maintain the parallelism of the optical axes of the two lenses obtained by the structure of the first embodiment, in addition to the alignment in the direction perpendicular to the optical axis (the above-described XY) (Adjustment of direction) is completed or simplified, and assembling can be performed more easily than in the first embodiment.
[0053]
Further, the structure of the second embodiment is not limited to the uneven step. For example, by adopting a structure having a tapered surface at the joint surface of the optical component, the same effect as in the second embodiment can be sold. FIG. 9 shows an example of the configuration. The joining surface is a tapered surface 91.
[0054]
(Example 3)
As a third embodiment, an example will be described in which the WDM three-terminal filter module according to the first and second embodiments is configured on a silicon bench.
[0055]
Photoresist is applied to a silicon single crystal and exposed with a predetermined mask, and then anisotropically etched using a KOH solution to perform V-grooves (grooves for mounting optical fibers and the like) and trapezoidal grooves ( A recess, such as a groove for mounting an optical component such as a lens, that allows positioning of the optical component was formed. This is called a silicon bench.
[0056]
In this embodiment, as shown in FIGS. 10A and 10B, an optical fiber for incident light and an optical fiber for reflected light are provided on a silicon bench 101. This is an example in which a WDM three-terminal filter module is configured by arranging and mounting a collimating lens, a thin film filter, a second collimating lens provided with a joint portion according to the present invention, and an optical fiber for transmitted light. As the form of the joint-integrated lens, the same one as in Example 1 was used.
[0057]
First, in the same manner as in the first embodiment, the adjustment and assembly are performed such that the four members of the incident light fiber, the first collimating lens, the second collimating lens, and the transmitted light fiber are coupled with low loss. By using lithography and anisotropic etching as described above, V-grooves and trapezoidal grooves in which optical components are arranged can be processed with high precision. Therefore, when each optical fiber is mounted in the V-groove 102, the positioning is completed. The first and second collimating lenses are mounted on the trapezoidal groove 103 by directly abutting the contact surfaces of the bonding portion according to the present invention. When this structure is adopted, first, the structure of the joining portion maintains the parallelism of the optical axes of the first collimating lens and the second collimating lens, and determines the center distance of each lens. By mounting the lens in the trapezoidal groove 103, the position of the optical axis of each lens in the XY plane is determined. That is, the adjustment elements remaining at the stage of mounting each fiber and each lens are only the positions in the Z-axis direction of the “set of collimating lenses in which the bonding portions are bonded to each other”, and most of the positioning and optical axis adjustment is completed.
[0058]
The test light is incident from the incident light filter, the transmitted light is monitored, and the position of the “set of collimating lenses” in the Z-axis direction is adjusted so that the loss is minimized. Fix with an adhesive. Thereafter, a thin-film filter is loaded and the characteristics are adjusted.
With the above configuration, more simple positioning and optical axis adjustment can be performed, and the assembling process can be simplified.
[0059]
Further, as shown in FIG. 10B, a convex portion 104 as a positioning means for keeping the distance between the end of the optical fiber and the lens constant is provided in the trapezoidal groove 103 on the silicon bench where the lens is mounted. Then, by attaching the outer edge of the first collimating lens to the convex portion so as to abut, the adjustment of the position of the “set of collimating lenses” in the Z-axis direction is completed. That is, it is possible to adopt a configuration in which the positioning and optical axis adjustment steps of each optical component are all completed at the stage of loading them.
[0060]
[Effects of the present invention]
In the optical communication module, at least a first optical member, a second optical member, and a third optical member are arranged in this order on an optical path of optical communication, and the third optical member is a first optical member. By directly joining the optical components, the parallelism and the position of the optical axis of each optical component can be easily adjusted, and the module assembling process can be simplified.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a configuration of a WDM three-terminal thin film filter module.
FIG. 2 is a joint-integrated lens according to an embodiment of the present invention.
FIG. 3 is a sleeve according to an embodiment of the present invention.
FIG. 4 is an assembly view of a dual capillary unit according to an embodiment of the present invention.
FIG. 5 is an assembly view of a dual capillary and a first collimating lens according to an embodiment of the present invention.
FIG. 6 is an assembly view of a WDM three-terminal thin film filter module according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view of a WDM three-terminal thin-film filter module according to an embodiment of the present invention.
FIG. 8 is a sectional view of a WDM three-terminal thin film filter module according to an embodiment of the present invention.
FIG. 9 is a sectional view of a WDM three-terminal thin-film filter module according to an embodiment of the present invention.
FIG. 10 is a sectional view of a WDM three-terminal thin film filter module according to a second embodiment of the present invention.
[Explanation of symbols]
11 First collimating lens 12 Second collimating lens 13 Thin film filter 14 Dual capillary 15 Single capillary 16a Optical fiber for incident light,
16b Optical fiber for reflected light 16c Optical fiber for transmitted light
21 Joint part integrated lens 21a Joint part 21c Contact surface 31 Sleeve 31a Slit 31b Hole 31b for filling with adhesive
31c Hole 31c for loading thin film filter
44 The end face of the fiber is the end face of the capillary 45 The antireflection film 52a The adjustment arm 52b The adjustment arm 81 The step 82 which is convex at the junction of the first collimating lens 82 The step 91 at the junction of the second collimating lens 91 Tapered surface 101 Silicon bench 102V Groove 103 Trapezoidal groove 104 Convex part as positioning means

Claims (7)

An optical communication module, wherein at least a first optical member, a second optical member, and a third optical member are arranged in this order on an optical path of optical communication, and the third optical member is a first optical member. An optical communication module, which is bonded to an optical member. The optical communication module according to claim 1, wherein a part or all of the joining surface is a tapered surface. 2. The optical communication module according to claim 1, wherein a part or all of the joining surfaces have a step. 4. The optical communication module according to claim 1, wherein the first optical member is a first collimating lens, the second optical member is an optical filter, and the third optical member is a second optical member. An optical communication module, which is a collimating lens. On a silicon bench, at least a first optical member, a second optical member, an optical communication module in which a third optical member is installed, on the optical path of the optical communication, the first optical member, the second An optical member and a third optical member are arranged in this order, and the third optical member is joined to the first optical member. The optical communication module according to claim 5, wherein a concave portion in which the optical member is provided is provided on the silicon bench. The optical communication module according to claim 6, wherein a convex portion is formed inside the concave portion, and the convex portion and the first optical member are in contact with each other. .

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