WO2016132913A1

WO2016132913A1 - Optical element and method for manufacturing optical element

Info

Publication number: WO2016132913A1
Application number: PCT/JP2016/053311
Authority: WO
Inventors: 一啓和田; 秀之藤森
Original assignee: コニカミノルタ株式会社
Priority date: 2015-02-16
Filing date: 2016-02-04
Publication date: 2016-08-25

Abstract

Provided is an optical element capable of obtaining a desired linear expansion coefficient by using a material with glass fiber mixed therein. In an optical element that transmits a light beam emitted from a light source with a single light source wavelength, the optical element is composed of a plurality of optical surfaces arrayed so that a light beam is incident thereon or reflected therefrom. The optical element is formed from a material composed of a resin with glass fiber mixed therein. When the optical surfaces are arranged in a matrix, a resin inlet is provided along whichever of the row arrangement or the column arrangement that has a greater distance than the other between optical surfaces at both ends in the arrangement direction.

Description

Optical element and optical element manufacturing method

The present invention relates to an optical element suitably used for, for example, optical communication or a copying machine, and an optical element manufacturing method.

In various information / signal processing devices including network devices such as routers, servers, and large computers, information / signal processing is becoming larger and faster. In these devices, signal transmission between a CPU and a memory on a circuit board (board), between wiring boards, between devices (rack), and the like has been conventionally performed by electrical wiring. However, because of superiority in terms of transmission speed, transmission capacity, power consumption, radiation from the transmission line, electromagnetic wave interference with the transmission line, etc., instead of the above-mentioned electrical wiring, a signal is transmitted by light using an optical fiber or the like as the transmission line. So-called optical interconnection for transmission is actually being introduced.

In such an optical interconnection, an optical transmission module including a light emitting element that converts an electrical signal into an optical signal and transmits the optical signal, and an optical reception module including a light receiving element that receives the optical signal and converts it into an electrical signal. Alternatively, an optical transceiver module having both functions is used as a main optical component. These modules are collectively referred to as an optical module.

Large-capacity communication becomes possible by transmitting optical signals between optical modules in parallel using a transmission channel. As a transmission channel, an optical fiber is often used to transmit / receive optical signals in parallel between optical modules. Therefore, an optical coupling device is generally used for optical coupling between the optical fiber and the optical module.

By the way, optical fibers are basically flexible, so that they can be bent and slack to some extent. However, in general optical fibers, the minimum bend diameter allowed to ensure light transmission efficiency is specified. Has been. Therefore, when bending less than the minimum diameter is required due to installation space restrictions, etc., the optical fiber is cut and the optical coupling is performed by bending the optical path of the light beam transmitted between the cut optical fibers. The use of the coupling device may lead to more efficient storage as a whole and increase the light transmission efficiency. The merit of using such an optical coupling device is not limited to optical fibers, but can also occur in optical coupling between a light emitting element and an optical fiber or between an optical fiber and a light receiving element. Here, the light emitting element, the light source, the light receiving element, and the like are collectively referred to as an optical element.

In order to perform optical coupling between optical elements, an optical connector having a structure in which an optical path is bent may be used in an optical coupling device. As such an optical connector, a PT optical connector (standardized by JPCA-PE03-01-06S) that changes the optical axis by 90 ° inside the connector has been put into practical use. The PT optical connector is a board-mounted optical connector that optically couples a multi-core optical fiber body such as a multi-core optical fiber tape core wire and an optical element on a flexible wiring board.

On the other hand, in recent years, the amount of optical communication information has been increasing, and in addition, long-distance and high-speed transmission of information is desired. However, in the case of multimode fibers that have been used in the past, optical fiber core diameters of 50 μm and 62.5 μm are employed, and optical signals are transmitted in a plurality of modes. Occurs and mode dispersion occurs. Therefore, since data loss occurs due to mode dispersion, long-distance / high-speed transmission is not suitable.

On the other hand, the single mode fiber is an ultrafine fiber having a mode field diameter of 9.2 μm, and has an advantage that attenuation can be suppressed as much as possible by setting the propagation of the optical signal to one mode. Therefore, unlike a transmission method that uses many modes such as multimode fiber, the signal arrival time is single, so there is no mode loss and it is suitable for long-distance and high-speed transmission. Opportunities for fiber use have increased.

However, as one of the problems when using a single mode fiber, since the mode field diameter is as small as 9.2 μm, when optical coupling between an optical fiber and an optical element is performed using an optical connector, positional deviation is allowed. The degree is reduced, that is, the difficulty of assembly is increased. Particularly problematic is the case where a multi-core optical fiber body capable of independently transmitting information via a plurality of cores and a plurality of optical elements are optically coupled using a single optical connector. An optical connector used for such an application generally has a plurality of lens surfaces for propagating light to individual optical fibers and optical elements, but when such an optical connector is formed from a resin, For example, due to thermal expansion due to changes in environmental temperature, there is a possibility that the optical fiber core-to-core distance and the distance between the lens surfaces may be shifted, thereby making it impossible to perform optical coupling between some optical fibers and optical elements. . On the other hand, in order to suppress optical loss during information transmission, the optical connector needs to secure a certain degree of transparency (transmittance).

To solve this problem, if glass is used as the material of the optical connector, the difference in thermal expansion approaches the optical fiber while having high transparency. Can be suppressed. However, since glass is inferior in moldability compared to resin, it is unsuitable for mass production, and there is a problem that costs increase.

On the other hand, as shown in Patent Documents 1 and 2, there is an attempt to mold an optical element with a material close to the characteristics of glass by mixing glass fiber into resin.

JP 2006-312706 A JP 2006-169324 A

However, as shown in Patent Documents 1 and 2, when an optical element is used using a material mixed with glass fiber, there is a problem that a desired linear expansion coefficient cannot be obtained depending on molding conditions.

The present invention has been made in view of the above-described problems, and provides an optical element capable of obtaining a desired linear expansion coefficient using a material mixed with glass fiber and a method for manufacturing the optical element. Objective.

In order to achieve at least one of the above objects, an optical element reflecting one aspect of the present invention is an optical element that transmits a light beam emitted from a light source having a single light source wavelength.
The optical element is formed by arranging a plurality of optical surfaces on which the light flux is incident or reflected,
The optical element is molded from a mixed material of resin and glass fiber,
When the optical surfaces are arranged in a matrix, a resin inflow port exists in the arrangement direction in which the distance between the optical surfaces at both ends in the arrangement direction is longer, among the arrangement in the row direction and the arrangement in the column direction. And

Hereinafter, the principle of the present invention will be described. First, the present inventors considered the cause of the unstable linear expansion coefficient in an optical element molded using a material in which a glass fiber is mixed into a resin. The present inventors actually formed an optical element using a mold from a material in which the amount of glass fiber mixed into the resin was changed, and the linear expansion amount when the temperature was raised from 30 ° C. to 60 ° C. Was measured, and the result shown in FIG. 1 was obtained. Here, in FIG. 2 schematically showing the material flow state inside the mold cavity CV at the time of molding the optical element, the direction in which the material flows into the mold through the resin inlet (gate) GT is shown. MD and the direction orthogonal to it were taken as TD. Note that the expression “mixed” is used because it is sufficient if the resin material and the glass filler are mixed. However, since the glass filler is usually mixed with the resin material and molded, the expression “mixed” is used in this description. Sometimes used to explain.

According to FIG. 1, it was found that the linear expansion amount in the TD direction does not change so much even when the temperature rises when the glass fiber mixing amount is 20 wt% or more. On the other hand, it has been found that the linear expansion amount in the MD direction is always lower than the linear expansion amount in the TD direction, and gradually decreases as the mixing amount of the glass fiber increases. Particularly in the MD direction, when the glass fiber mixing amount is 30% wt or more, the linear expansion amount is 21 ppm or less.

A general multi-core optical fiber tape core wire covers a plurality of exposed fiber strands with a so-called secondary layer surrounding portion. As the material of the surrounding portion, a UV curable resin including a glass fiber is often used because it is relatively inexpensive. In such a case, the distance between the cores of the fiber strands when the temperature changes is determined by the amount of linear expansion of the secondary layer. Here, when the dimension of the lens surfaces in the optical element is set to 3 mm, when the temperature is increased from 25 ° C. to 85 ° C., the amount of extension of the surrounding portion made of the UV curable resin including the glass fiber is 1 mm. Since the linear expansion amount of the material per 1 ° C. is 20 ppm, 20 × (85−25) × 3 = 0.636 mm. On the other hand, the amount of elongation in the MD direction of an optical element molded using a material in which the amount of glass fiber mixed into the resin is 30% wt or more at the same temperature rise is 1 mm per 1 ° C. from the result of FIG. Since the linear expansion amount of the material is 21 ppm, 21 × (85−25) × 3 = 0.038 mm. Therefore, the difference in elongation between the two is 0.0038−0.0036 = 0.0002 mm. Note that the allowable tolerance of the difference in elongation required for the optical connector is less than 0.001 mm. Under the same conditions, (0.0036 + 0.001) / ((85−25) × 3) = 25 It will be acceptable to less than 5 ppm. That is, while the extension amount of the optical element in the MD direction is within the allowable range, the extension amount of the optical element in the TD direction is outside the allowable range under the same conditions.

The present inventors considered the reason why the linear expansion characteristic changes depending on the flow direction of the material during molding. According to the study by the present inventors, referring to FIG. 2, when the glass fiber GF, which is a fine rod mixed in the resin PL, flows into the cavity CV of the mold through the gate. It has been found that the longitudinal direction tends to coincide with the flow direction (that is, the MD direction). When the resin PL is solidified in such a state that the glass fiber GF is oriented along the MD direction, when the resin PL expands when the temperature rises, the binding force of the glass fiber GF in the TD direction orthogonal to the MD direction. However, in the MD direction, the influence of the restraining force of the glass fiber GF is large, and the expansion of the resin PL is suppressed. That is, the amount of linear expansion is more easily suppressed on the MD direction side than the TD direction.

Based on the above knowledge, at the time of molding the optical element, in a state in which a material made by mixing glass fiber into the resin is flowable, it is caused to flow in the mold along the alignment direction of the optical surfaces on which the light beam is incident or reflected ( That is, it was found that an optical element capable of suppressing the amount of linear expansion between the optical surfaces at the time of temperature change can be formed by solidifying the optical surfaces in the MD direction. Thereby, in the optical element, linear expansion in a direction in which linear expansion due to temperature change tends to be a problem can be suppressed.

Here, it is generally difficult to determine the flow direction of the resin during molding by visually observing the optical element after molding. However, when the optical element is injection-molded, the molten resin is introduced into the cavity formed in the mold through the gate, so that the resin in the gate is also solidified when the resin is solidified. As an entrance), the mold is released along with the optical element. Therefore, the flow direction of the resin can be estimated from the resin inlet of the optical element. Although the gate trace of the optical element can be deleted by post-processing, the position of the gate trace can be found by observing the birefringence state of the optical element even in that case. The direction in which the amount of linear expansion between the optical surfaces when the temperature changes can be suppressed is known. Therefore, the “resin inlet (gate trace)” includes a portion that can be inferred from the birefringence state of the molded optical element in addition to the resin that is solidified in the gate and attached to the optical element. .

FIG. 3 is a diagram of an optical element OE having a plurality of optical surfaces OP as an example of the present invention as viewed from the optical axis side of the optical surface OP. The optical surface OP is formed side by side on the rectangular surface RP. In FIG. 3, the resin inlet GTO is separated from the optical element OE at a position indicated by a dotted line after molding, but may be left as it is.

As shown in FIG. 3A, when the optical surfaces OP of the optical elements OE are arranged in a line, a virtual surface VP passing through the optical axis (represented by a straight line extending in the vertical direction in FIG. 3A). Is parallel to the resin inlet GTO, it can be seen that the material flows into the mold through the gate corresponding to the resin inlet GTO during molding and flows in the direction in which the optical surfaces OP are aligned. It can be seen that the expansion can be suppressed. Here, as shown in FIG. 3A, two (or more) resin inflow ports GTO may be provided, but the resin inflow ports GTO may be provided at positions facing each other so that the virtual planes VP intersect each other. desirable. At this time, there may be a difference in the arrangement of the optical surface and the size of each gate so that the weld line generated at the joint of the resin flowing in from each gate does not occur on the optical surface. Note that, as shown in FIG. 3A, a shape (for example, a 1 × 4 array) in which the optical surfaces OP are arranged in a line is also included in the matrix. In addition, the matrix shape includes a 2 × 2, 3 × 4 arrangement, and as shown in FIG. 3D, the optical surfaces OP are staggered, for example, so that there is no optical surface in a part of the matrix. It also includes those that are.

3C, when the optical surfaces OP of the optical element OE are arranged in a matrix with a plurality of rows and columns, both ends of the rows in the row direction and the columns in the optical surface OP are arranged. If the resin inlet GTO is provided in parallel with the straight line EL connecting the optical axes of at least two optical surfaces OP aligned along the longer alignment direction, the resin flow during molding is reduced. It can be seen that the material has flowed into the mold through the gate corresponding to the entrance GTO and has flowed in the direction in which the optical surface OP is longer, and linear expansion in this direction can be suppressed. Further, as shown in FIG. 3B, the resin inflow port GTO may be provided so as to include a straight line EL passing through the middle of the two rows of optical surfaces OP.

In the optical element, when the length of one side of the surface having the resin inlet of the optical element is α, the width of the resin inlet in the direction of the one side is α / 5 or more and α or less, When the thickness of the optical element is β, the thickness of the resin inlet in the same direction is preferably β / 5 or more and β or less.

FIG. 5A shows a mold for molding an optical element as an example of the present invention in a clamped state, and FIG. 5B shows the configuration of FIG. 5A in the VB-VB line. It is the figure which divided | segmented in the position (parting line) of and looked at in the arrow direction. The mold MD1 shown in FIG. 5 has a plurality of optical surface transfer surfaces OPP and a rectangular flange surface transfer surface FPP, and the mold MD2 opposite to this has a surface other than that of the optical element. It has a back side transfer surface BPP to be formed. The gate GT as a resin inlet is formed by combining a rectangular cross-sectional groove GT2 provided on the mold MD2 side and an extended surface GT1 of the flange surface transfer surface FPP of the mold MD1.

Here, when the length of the upper side of the flange surface transfer surface FPP is Wp (= α) and the width of the gate GT in the same direction is Wg, it is preferable that the expression (1) is satisfied.
Wp / 5 ≦ Wg ≦ Wp (1)
Further, when the depth of the back transfer surface BPP (corresponding to the thickness of the molded optical element) is Dp (= β) and the depth of the gate GT is Dg, it is preferable that the formula (2) is satisfied.
Dp / 5 ≦ Dg ≦ Dp (2)
Thereby, a raw material can be smoothly flowed in metal mold | die MD1, MD2 via the gate GT. By transferring the flange surface transfer surface FPP connected to the gate GT, a flange surface of the optical element is formed, and this surface becomes a surface having a resin inlet. That is, when the length of one side of the rectangular surface of the optical element is α, the width of the resin inlet in the direction of the side is α / 5 or more and α or less, and the thickness of the optical element is β In addition, an optical element in which the thickness of the resin inlet in the same direction is β / 5 or more and β or less can be molded.

When the rectangular surface of the optical element is flush with the material solidified in the resin inlet, for example, as shown in FIG. 5, the flange surface transfer surface FPP and an extension that forms part of the gate GT are formed. It means that the surface GT1 is flush with the surface GT1. Thereby, a raw material can be smoothly flowed in metal mold | die MD1, MD2 via the gate GT.

The optical surface of the optical element is used to optically couple a plurality of optical elements and a multi-core optical fiber body, and includes a plurality of fiber strands facing the optical element in the multi-core optical fiber body. It is preferable that the linear expansion coefficient of the surrounding enclosure part and the linear expansion coefficient of the optical element are substantially equal. Thereby, the plurality of optical elements and the optical fiber of the multi-core optical fiber body can be optically coupled with high accuracy. “The linear expansion coefficient is substantially equal” means that the linear expansion coefficient with the smaller linear expansion coefficient falls within ± 20% of the larger linear expansion coefficient.

In order to achieve at least one of the above objects, another optical element reflecting one aspect of the present invention is an optical element that transmits a light beam emitted from a light source having a single light source wavelength.
In the optical element, an optical surface on which the light beam is incident or reflected is an ellipse or a rectangle having a major axis and a minor axis when viewed in the optical axis direction,
The optical element is molded from a material formed by mixing resin and glass fiber,
A resin inflow port exists in the long axis direction.

As described above, at the time of molding the optical element, the material mixed with the resin and the glass fiber is made flowable and flows into the mold through the resin inlet along the long axis direction of the optical surface ( In other words, the major axis direction of the optical surface is made substantially parallel to the MD direction), and if solidified thereafter, the amount of linear expansion in the major axis direction between the elliptical optical surfaces at the time of temperature change can be suppressed. A good optical element can be molded.

When the optical surface OP of the optical element OE is elliptical when viewed in the optical axis direction when viewed in the directions shown in FIGS. 4A and 4B, a straight line EL extending the long axis is formed at the resin inlet GTO. If it is provided in parallel, it can be seen that the material has flowed into the mold through the gate corresponding to the resin inlet GTO during molding, and the linear expansion in this direction can be suppressed. Note that an optical element such as an fθ lens improves handling by cutting a region in the vicinity of an unused edge of the optical surface in parallel, and when viewed in the optical axis direction, it may appear rectangular. However, even in such a case, since the remaining optical surface is a toric surface or the like, it is treated as having a major axis and a minor axis.

The optical element is preferably formed by injection molding. Thereby, optical elements can be mass-produced at low cost. In addition, a thermoplastic resin etc. can also be used as a raw material of an optical element.

Further, the mixing (mixing) amount of the glass fiber is preferably 2 to 40 wt%. By making the mixing amount of the glass fiber 2 wt% or more, it is possible to obtain an effect sufficient to suppress the amount of linear expansion. On the other hand, by making the mixing amount of the glass fiber 40 wt% or less, a glass filler It is possible to avoid adverse effects such as an increase in the amount of mixing and the injection becomes impossible and the moldability deteriorates.

The resin is polycarbonate (PC), polymethyl methacrylate (PMMA), polyolefin resin, transparent polyamide (PA), polysulfone (PSU) / polyphenylenesulfone (PPSU), polyethersulfone (PES), polyether. It is preferably either imide (PEI) or polyetheretherketone (PEEK). Such a resin is suitable as a material for an optical element because it is excellent in transparency and has good compatibility with a glass fiber.

The shape of the glass fiber is preferably a rod-like body having a cross section of 5 to 50 μm and a length of 10 to 500 μm. Thereby, a general glass fiber can be utilized.

The light source wavelength is preferably 850 ± 150 nm, 1310 ± 150 nm, or 1550 ± 150 nm. Since such a light source wavelength is frequently used in optical communication or the like, it is preferable that it can cope with these.

In order to achieve at least one of the objects described above, an optical element manufacturing method reflecting one aspect of the present invention is an optical element manufacturing method that transmits a light beam emitted from a light source having a single light source wavelength.
The optical element is formed by arranging a plurality of optical surfaces on which the light flux is incident or reflected,
Molding the optical element by allowing the material mixed with resin and glass fiber to flow in the mold along the direction of alignment of the optical surfaces and then solidifying the mold. It is characterized by.

In order to achieve at least one of the above-described objects, another optical element manufacturing method reflecting one aspect of the present invention is a method for manufacturing an optical element that transmits a light beam emitted from a light source having a single light source wavelength. In
In the optical element, an optical surface on which the light beam is incident or reflected is an ellipse or a rectangle having a major axis and a minor axis when viewed in the optical axis direction,
The optical element is molded by allowing the material mixed with resin and glass fiber to flow in the mold along the major axis direction of the optical surface through the gate and then solidifying the material. It is characterized by that.

The term “single light source wavelength” means that a single light source wavelength is used for a specific purpose. For example, in optical communication, the same light source wavelength is used for upstream communication and downstream communication. In such a case, the light source wavelength at the time of upstream communication is single, and the light source wavelength at the time of downstream communication is single.

As the glass fiber, general-purpose E glass, C glass, A glass, S glass, D glass, NE glass, T glass, quartz glass, and the like may be used. For example, silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), calcium oxide (CaO), titanium oxide (TiO ₂ ), boron oxide (B ₂ O ₃ ), magnesium oxide (MgO), zinc oxide (ZnO), barium oxide (BaO), zirconium oxide (ZrO ₂₎ ), Lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), etc., and the ratios of which are appropriately adjusted can be used.

The glass fiber can be obtained by using a conventionally known method for spinning long glass fibers. For example, the glass raw material is continuously vitrified in a melting furnace, led to fore-haas, and a direct melt (DM) method in which a bushing is attached to the bottom of the fore-heart and spun, or the melted glass is processed into marble, cullet, or rod shape The glass can be made into fiber using various methods such as a remelting method in which it is remelted and spun.

The diameter of the glass fiber is not particularly limited, but a glass fiber having a diameter of 5 to 50 μm is preferably used. If it is thicker than φ50 μm, the filling pressure at the time of injection molding becomes high, which may lead to insufficient transfer to the mold. When it is thinner than Φ5 μm, the dispersion uniformity of the glass fiber is lowered, and the linear expansion characteristic may vary in the product.

In addition, there have been attempts to mold an optical element using a resin material mixed with particles having a diameter of 30 nm or less, for example. The problem is that the resin material tends to become hard due to increase, making it difficult to mold, and further, the surface area of the particles increases to increase the hydrophilicity, the water absorption of the molded optical element increases, and the optical characteristics change. There was a problem. On the other hand, this problem can be solved by setting the glass fiber to φ5 to 50 μm.

According to the present invention, it is possible to provide an optical element capable of obtaining a desired linear expansion coefficient using a material mixed with glass fiber and a method for manufacturing the optical element.

It is a figure which shows the relationship between the linear expansion | swelling of resin with which glass fiber mixed, and the mixing amount of glass fiber. It is a figure which shows typically the cavity CV of the metal mold | die which shape | molds an optical element. It is the figure which looked at optical element OE which has a plurality of optical surfaces OP which becomes an example of the present invention from the optical axis side of optical surface OP. It is the figure which looked at the optical element OE which has the elliptical optical surface OP which is another example of this invention from the optical axis side of the optical surface OP. (A) shows a mold for molding an optical element as an example of the present invention in a clamped state, and (b) shows the configuration of (a) at the position of the VB-VB line (parting line). ) And viewed in the direction of the arrow. It is a perspective view shown in the state which decomposed | disassembled the optical coupling device 100 concerning this embodiment. 2 is a cross-sectional view of the optical coupling device 100 along one optical axis. FIG. It is a figure which expands and shows the edge part of the multi-core optical fiber body. 3 is a perspective view of an optical path changing element 120 used in the optical coupling device 100. FIG. 3 is an enlarged sectional view of an optical path changing element 120. FIG. It is a perspective view which shows the metal mold | die which forms an optical path changing element. It is a figure which shows the process of shape | molding an optical path changing element with resin which mixed glass fiber.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 6 is a perspective view showing the optical coupling device 100 having the optical path changing element as the optical element according to the present embodiment in an exploded state. FIG. 7 is a cross-sectional view of the optical coupling device 100 along the optical axis. FIG. 8 is an enlarged view showing the end portion of the multi-core optical fiber body 132. FIG. 9 is a perspective view of the optical path changing element 120 used in the optical coupling device 100. FIG. 10 is an enlarged cross-sectional view of the optical path changing element 120. The following configuration is a schematic diagram, and some shapes, dimensions, and the like are different from actual ones.

As shown in FIGS. 6 and 7, the optical coupling device 100 includes an optical module 110, an optical path changing element 120, and an optical connector 130. Here, the optical module 110 has a function of transmitting light, and can be installed on a substrate that is stacked and inserted on the back surface of a large-capacity server or the like. The substrate itself may be the optical module 110. The optical module 110 includes a plurality of VCSEL type semiconductor lasers 112 which are light emitting elements arranged in a row on a base plate 111 having a rectangular shape and a flat upper surface. The light source wavelength of the semiconductor laser 112 is any one of 850 nm, 1310 nm, and 1550 nm. On the base plate 111, cylindrical pins 113 are arranged in the vicinity of both ends of the semiconductor laser 112 in the arrangement direction. Note that unevenness or the like for positioning the optical path changing element 120 may be formed around the semiconductor laser 112. The NA of the optical module 110 is 0.1 to 0.6.

The optical connector 130 includes a main body 131 formed of resin, and is connected to the multi-core optical fiber body 132 and has a function of holding it.

As the multi-core optical fiber body 132, for example, an all-quartz multi-mode optical fiber or a single-mode optical fiber can be used. Here, a multi-core optical fiber tape (ribbon) having a plurality of optical fibers is used. Is used. The multi-core optical fiber body 132 is covered with a resin protection portion 132a except for both exposed ends. On the other hand, as shown in FIG. 8, a plurality of fiber strands 132b are exposed at the end of the multi-core optical fiber body 132, and a tube-shaped primary layer 132c made of resin around each fiber strand 132b. The primary layer 132c is covered with an integral secondary layer 132d. The material of the secondary layer 132d that is the surrounding portion is UV curable resin or glass mixed with glass fiber, and the linear expansion coefficient is substantially equal to the linear expansion coefficient of the optical element.

The main body 131 is formed in a thick rectangular plate shape, and one side is cut out in a rectangular shape when viewed from above in FIG. 6 to form a recess 131a. As shown in FIG. 7, an insertion hole 131 b into which the multicore optical fiber body 132 is inserted is formed on the opposite side of the main body 131 from the recess 131 a. The insertion hole 131b has a wide rectangular cross section so that the protection part 132a as a coating of the multi-core optical fiber body 132 can be accommodated. A long hole 131c penetrating from the bottom surface of the insertion hole 131b toward the recess 131a is formed. A secondary layer 132d provided at the end of the multi-core optical fiber body 132 is inserted through the long hole 131c.

The bottom surface 131d of the recess 131a where the long hole 131c is exposed is orthogonal to the lower surface 131e of the main body 131. As shown in FIG. 6, a pair of circular openings 131f having the same diameter as the pin 113 are formed on both sides of the recess 131a so as to sandwich the recess 131a.

9 and 10, the optical path changing element 120 is integrally formed of a resin mixed with a predetermined amount of glass fiber as will be described later. The optical path changing element 120 has an elongated triangular prism shape, and has a first surface 121, a second surface 122, and a third surface 123. The first surface 121 and the third surface 123 are orthogonal to each other. In addition, it is preferable from a viewpoint of size reduction that the magnitude | size of the optical axis direction (OA1, OA2 direction) of the optical path change element 120 is 10 mm or less. Further, from the viewpoint that the optical fiber can be made smaller than the minimum diameter when the optical fiber is bent, the size is more preferably 5 mm or less. However, the length of the light beam path passing through the optical element is preferably about 1 mm. When the length of the light path is smaller than 1 mm, it is possible to use a material having a low transmittance, and conversely, when the length of the light path is larger than 1 mm, a material having a high transmittance is used. By using it, it is possible to ensure a sufficient transmittance as an optical path polarizing element.

The first surface 121 is a flat surface, and has a function of entering a light beam emitted from the semiconductor laser 112 of the optical module 110. The second surface 122 includes a plurality of reflective surfaces 122a arranged in a line, a planar connecting surface 122b formed around the reflecting surface 122a, and an outer periphery of the second surface 122 so as to surround the connecting surface 122b. And a protruding portion 122c having a rectangular frame shape. It is preferable that an inclined surface 122d is formed between the connecting surface 122b and the protruding portion 122c. The third surface 123 is a flat surface and has a function of transmitting the light beam reflected from the reflecting surface 122a.

Each of the reflecting surfaces 122a has the same shape protruding from the connecting surface 122b. Specifically, the reflecting surface 122a has an elliptical shape when viewed from the front, and bends the optical axis by 90 ° when a conical divergent light beam is incident. It has an anamorphic free-form surface that can reflect a conical convergent light beam. In the example of FIG. 9, a toroidal surface (an anamorphic surface in a broad sense) having an elliptical shape in one direction is formed. Thereby, the aberration can be almost eliminated. The arrangement interval of the reflecting surfaces 122a is equal to the arrangement interval of the semiconductor lasers 112 of the optical module 110 and the arrangement interval of the fiber strands 132b inserted into the long holes 131c. The arrangement direction of the reflection surfaces 122a is a direction orthogonal to a surface including two optical axes of one reflection surface 122a. The angle (acute angle) formed between the tangential plane at the outer peripheral edge of the reflecting surface 122a and the optical axis is usually 75 degrees or less. The distance between the protrusion 122c and the reflecting surface 122a is preferably 0.05 mm or more from the viewpoint of not affecting the coupling efficiency.

The height from the connecting surface 122b of the protruding portion 122c is uniform over the entire circumference, and is larger than the protruding amount of the reflecting surface 122a. Therefore, as shown in FIG. 10, when the virtual plane VP that contacts the entire circumference (here, the plane portion) of the protrusion 122c is defined, the virtual plane VP does not contact the reflecting surface 122a. The virtual plane VP is parallel to a tangential plane at an arbitrary point on the reflecting surface 122a (in this example, the point PT on the optical axis is at least a point inside the outer peripheral edge of the reflecting surface 122a). ing.

In FIG. 10, assuming that the optical axis on the optical module 110 side in one reflective surface 122a is OA1, and the optical axis on the optical connector 130 side is OA2, the optical axes OA1 and OA2 are orthogonal on the reflective surface 122a. The distance along the optical axis OA1 from the first surface 121 to the reflective surface 122a (or the distance along the optical axis from the third surface 123 to the reflective surface 122a) is A, and the point on the optical axis OA1 of the reflective surface 122a When the distance from PT to the virtual plane VP is B, the following expression is satisfied. The distance A is usually 0.0625 mm or more and 2.9 mm or less.
B / A <1.0 (1)

The optical path changing element 120 has a parallel plate-like cover member 125 bonded to the entire periphery of the protruding portion 122c so as to overlap the virtual plane VP. It is preferable that the cover member 125 is a light-shielding member because deterioration of the optical path changing element 120 can be suppressed and light from the outside can be prevented from entering the lens. When the cover member 125 is provided, a gap is formed between the reflective surface 122a and the cover member 125 damages the reflective surface 122a, or a reflective film is formed on the reflective surface 122a. There is no risk of injury. In addition, since the cover member 125 can be provided so as to overlap the virtual plane VP, it is possible to contribute to miniaturization in the stacking direction even when the substrate provided with the optical coupling device 100 is stacked. Furthermore, by sealing the reflective surface 122a in a sealed space with the cover member 125, the reflective surface 122a can be protected from adverse effects of the external environment, such as adhesion of foreign matter. Further, the gap between the reflecting surface 122a and the virtual plane VP may be sealed with a resin to prevent the attachment of foreign matter and condensation. Although sealing with the cover member 125 or resin is not necessarily performed, it is preferable to perform sealing with the cover member 125 or resin for the reasons described above. As shown in FIG. 10, it is preferable that the cover member 125 has a shape that does not protrude outward from the optical path changing element 120 when attached to the optical path changing element 120 because the optical coupling device 100 can be downsized.

(Formation of optical path changing element)
FIG. 11 is a perspective view showing a mold for forming the optical path changing element, and FIG. 12 is a diagram showing a molding process of the optical path changing element with resin. As shown in the figure, the first mold MD1 has a V-groove-shaped transfer surface composed of slopes MD1a and MD1b, and a gate GT connected to the V-groove. On the other hand, the second mold MD2 has an optical surface transfer surface MD2a, a joint surface transfer surface MD2b, and a protruding portion transfer surface MD2c.

Here, the optical path changing element is molded using a material in which 2 to 40 wt% of glass fiber is mixed into the resin. The elongated rod-like glass fiber is crushed and mixed with a resin material at a rate of 2 to 40 wt%, and the mixed material is molded by an injection molding machine. The transmittance of the resin is preferably 50% or more at the light source wavelength in a state where the resin is molded into a parallel plate having a thickness of 3 mm. The glass fiber is preferably a rod-like body having a cross section of 5 to 50 μm and a length of 10 to 500 μm. Moreover, wt% means weight%.

As shown in FIG. 12A, the mold material is clamped so that the lower surface of the first mold MD1 and the upper surface of the second mold MD2 are in close contact with each other, and the resin material melted from the outside through the gate GT is Pour into the cavity of the second mold MD2. The resin material flowing in from the gate GT flows along the alignment direction of the optical surface transfer surface MD2a.

The first surface 121 of the optical path changing element 120 is transferred and molded by the inclined surface MD1a of the first mold MD1, and the third surface 123 is transferred and molded by the inclined surface MD1b. On the other hand, the reflecting surface 122a of the optical path changing element 120 is transferred and molded by the optical surface transfer surface MD2a of the second mold MD2, the connecting surface 122b is transferred and formed by the connecting surface transfer surface MD2b, and the protruding portion 122c by the protruding portion transfer surface MD2c. Is transferred and molded.

After solidifying the resin material, as shown in FIG. 12B, the molded optical path changing element 120 can be taken out by opening the first mold MD1 and the second mold MD2. According to the present embodiment, the resin material that has flowed in from the gate GT solidifies after flowing along the alignment direction of the optical surface transfer surface MD2a. Therefore, in the formed optical path changing element 120, the reflection surface 122a when the temperature rises. The linear expansion amount in the arrangement direction (that is, the longitudinal direction of the optical path changing element 120) can be kept small. On the other hand, since the secondary layer 132d of the multi-core optical fiber body 132 determines the inter-core distance of the optical fiber 132b when the temperature rises, the linear expansion amount of the optical path changing element 120 is changed to the linear expansion amount of the secondary layer 132d. By bringing them closer, the positional relationship between the optical fiber 132b and the corresponding reflecting surface 122a can be maintained with high precision, so that good optical coupling can be performed regardless of temperature changes.

The present invention is not limited to the embodiments described in the present specification, and includes other embodiments and modifications based on the embodiments and technical ideas described in the present specification. It is obvious to For example, the optical element of the present invention can be used not only for optical communication but also as an fθ lens used for a copying machine, or for a collimator or an optical pickup device of a small projector.

100 optical coupling device 110 optical module 111 base plate 112 semiconductor laser 113 pin 120 optical path changing element 121 first surface 122 second surface 123 third surface 125 cover member 130 optical connector 131 body 131a recess 131b insertion hole 131c long hole 131d bottom 131e Lower surface 131f Circular opening 132 Multi-core optical fiber body 132a Protection part 132b Fiber strand 132c Primary layer 132d Secondary layer

Claims

In an optical element that transmits a light beam emitted from a light source having a single light source wavelength,
The optical element is formed by arranging a plurality of optical surfaces on which the light flux is incident or reflected,
The optical element is molded from a mixed material of resin and glass fiber,
When the optical surfaces are arranged in a matrix, a resin inflow port exists in the arrangement direction in which the distance between the optical surfaces at both ends in the arrangement direction is longer, among the arrangement in the row direction and the arrangement in the column direction. An optical element.
When the length of one side of the surface having the resin inlet of the optical element is α, the width of the resin inlet in the direction of the one side is α / 5 or more and α or less, and the thickness of the optical element is 2. The optical element according to claim 1, wherein the thickness of the resin inlet in the same direction is β / 5 or more and β or less.
The optical surface of the optical element is used to optically couple a plurality of optical elements and a multi-core optical fiber body, and surrounds a plurality of fiber strands facing the optical element in the multi-core optical fiber body. The optical element according to claim 1, wherein a linear expansion coefficient of the portion and a linear expansion coefficient of the optical element are substantially equal.
In an optical element that transmits a light beam emitted from a light source having a single light source wavelength,
In the optical element, an optical surface on which the light beam is incident or reflected is an ellipse or a rectangle having a major axis and a minor axis when viewed in the optical axis direction,
The optical element is molded from a mixed material of resin and glass fiber,
An optical element, wherein a resin inflow port exists in the major axis direction.
5. The optical element according to claim 1, wherein a mixing amount of the glass fiber is 2 to 40 wt%.
The resin is polycarbonate (PC), polymethyl methacrylate (PMMA), polyolefin resin, transparent polyamide (PA), polysulfone (PSU) / polyphenylene sulfone (PPSU), polyethersulfone (PES), polyetherimide ( 6. The optical element according to claim 1, wherein the optical element is any one of PEI) and polyetheretherketone (PEEK).
The optical element according to any one of claims 1 to 6, wherein the glass fiber is a rod-like body having a cross section of 5 to 50 µm and a length of 10 to 500 µm.
8. The optical element according to claim 1, wherein the light source wavelength is any one of 850 ± 150 nm, 1310 ± 150 nm, and 1550 ± 150 nm.
In the method of manufacturing an optical element that transmits a light beam emitted from a light source having a single light source wavelength,
The optical element is formed by arranging a plurality of optical surfaces on which the light flux is incident or reflected,
Molding the optical element by allowing the material mixed with resin and glass fiber to flow in the mold along the direction of alignment of the optical surfaces and then solidifying the mold. A method for producing an optical element, characterized in that
In the method of manufacturing an optical element that transmits a light beam emitted from a light source having a single light source wavelength,
In the optical element, an optical surface on which the light beam is incident or reflected is an ellipse or a rectangle having a major axis and a minor axis when viewed in the optical axis direction,
The optical element is molded by allowing the material mixed with resin and glass fiber to flow in the mold along the major axis direction of the optical surface through the gate and then solidifying the material. A method for manufacturing an optical element.