JP2009168940A - Light splitter prism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To readily and adequately stick respective prism constituents to each other without bringing about any problem associated with optical characteristics and so on even when no severe constraint is added to the amount of an adhesive to laminate a plurality of prism constituents to one another and fix them. <P>SOLUTION: A plurality of prism constituents 2, 3, which are principally composed of triangular prisms and of which the refractive indexes are made identical or substantially identical to one another, are laminated and fixed to one another at respective one or more planes by using an adhesive. Thereby a rectangular prism shape, in which four outer surfaces 2a, 2b, 3c, 3d are combined together via their respective corner portions, is formed, and at the same time, the laminated surface 4 of the prism constituents is made such that light is transmitted and reflected by it according to the wavelength component of light. Furthermore, notches 4x leading to the laminated surface 4 are respectively formed on sites where the laminated surface 4 of the plurality of prism constituents 2, 3 reaches to the outer surface or to the corner portion, and the adhesive S squeezed out from the laminated surface 4 has been solidified and stuck to the notches 4x while being accumulated therein. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light separation prism formed by adhering a plurality of prism constituents whose basic shape as a main constituent element is a triangular prism to each other by adhering one or a plurality of surfaces to each other using an adhesive. .

  As is well known, for example, when optical communication is performed using an optical fiber, light in one direction (light of a predetermined wavelength component) is transmitted in the middle of the optical transmission path so as to travel straight, A light separation prism for reflecting light in the reverse direction (light of other predetermined wavelength components) to be bent at right angles is widely used. As disclosed in Patent Documents 1 and 2, this type of light separating prism is composed of two right-angled isosceles triangular prism-shaped prisms (prism pieces), and the bottom surfaces of the prisms are separated by a wavelength separation film. By pasting together, the cross section in which the angle formed by all adjacent surfaces is 90 degrees is usually configured as a square cuboid or cube.

  More specifically, as shown in FIG. 10, the light separation prism 31 includes a first outer surface 32 a and a second outer surface that are adjacent to each other with a corner (right-angled portion) facing the bottom surface of one first prism structure 32 as a boundary. 32b and a third outer surface 33c and a fourth outer surface 33d adjacent to each other with a corner (right angle portion) facing the bottom surface of the other second prism structure 33 as a boundary, the first outer surface 32a and the fourth outer surface 33d. The outer surface 33d is adjacent to the bonding surface 34 as a boundary, and the second outer surface 32b and the third outer surface 33c are adjacent to each other with the bonding surface 34 as a boundary.

  As an example of an optical communication system using this light separation prism, as shown in the figure, the fourth outer surface 33d of the light separation prism 31 is attached to the end face 36a of the ferrule 36 to which the optical fiber 35 is inserted and fixed. At the same time, the bonding surface 34 of the light separation prism 31 is inclined at an angle of 45 degrees with respect to the optical axis of the optical fiber 35, and the second outer surface 32 b is arranged so as to be orthogonal to the optical axis of the optical fiber 35. Is done. In the optical transmission by the optical communication system, the predetermined wavelength component of the light X1 irradiated from the light emitting element 37 such as a laser diode toward the second outer surface 32b of the light separating prism 31 is caused to travel straight on the bonding surface 34. While being transmitted and incident on the optical fiber 35, the other predetermined wavelength component of the light Y1 emitted from the tip of the optical fiber 35 is reflected by the bonding surface 34 of the light separation prism 31 so as to be bent at a right angle. After passing through the third outer surface 33c, light is received by a light receiving element 38 such as a photodiode. The refractive index of the light separation prism 31 is set higher than that of the optical fiber 35.

JP 2000-162413 A JP 2000-180671 A

  By the way, when the light separating prism 31 is manufactured, for example, an ultraviolet curable or thermosetting adhesive is used between the bottom surface of the first prism structure 32 and the bottom surface of the second prism structure 33. Although filling is performed, since it is extremely difficult to adjust the amount of the adhesive to an appropriate amount, the following problems occur.

  That is, when the amount of the adhesive is excessively small, a space in which the adhesive layer does not exist is formed on the bonding surface 34 of the two prism constituent bodies 32 and 33, and this causes the adhesive strength. In addition to a decrease in the water resistance, the water resistance is hindered by water entering the bonding surface 34, and further optical loss is caused such that light loss occurs. On the other hand, when the amount of the adhesive is excessively large, the adhesive overflows from the bonding surface 34 to any one of the outer surfaces 32a, 32b, 33c, and 33d, that is, the optical path surface. Also causes the occurrence of light loss. Therefore, regardless of whether the amount of the adhesive is excessive or too small, not only the yield is lowered, but also a careful and complicated sorting operation in terms of optical characteristics is required, resulting in an increase in production cost.

  In addition to the above configuration, the light separating prism includes the following. That is, the light separation prism 41 shown in FIG. 11 has two triangular prism-shaped prism structures 42 and 43 in the same manner as described above on one outer surface 43c of four outer surfaces formed by bonding the bottom surfaces to each other. The rectangular columnar prism structure 44 is bonded and fixed using an adhesive so as to form a square columnar shape (a cross section is a parallelogram) as a whole. In addition, the light separation prism 51 shown in FIG. 12 has four triangular prisms 52 that are bonded to each other using an adhesive so that the bottom surfaces 52a form four outer surfaces. By being fixed together, it is configured to form a quadrangular prism as a whole. Further, the light separating prism 61 shown in FIG. 13 is formed by bonding one surface of the triangular prism-shaped prism structure 63 to each of the two surfaces on both sides of the central triangular prism-shaped prism structure 62 by using an adhesive. The overall configuration is a quadrangular prism.

  In the light separation prism 41 shown in FIG. 11, the light indicated by symbol a in FIG. 11 advances straight, but the light indicated by reference symbol b travels straight after being reflected by the bonding surface 45, whereas the remaining part. Is reflected by the bonding surface 45 and the bonding surface 4b. In addition, the light separating prism 51 shown in FIG. 12 travels straight so that a part of the light is indicated by the symbol d, but the remaining part is reflected by the bonding surface 54 as indicated by the symbol e, and the other part is further reflected. The part is reflected by the bonding surface 55 as indicated by reference numeral f. In addition, the light separating prism 61 shown in FIG. 13 goes straight so that a part of the light is indicated by the symbol g, but the remaining part is reflected by the bonding surface 64 as indicated by the symbol h, and the other part is further reflected. The part is reflected by the bonding surface 65 as indicated by the symbol i.

  The amount of adhesive to be filled in the bonding surfaces 45, 4b, 53, 54, 55, 56, 64, 65 for any of the light separation prisms 41, 51, 61 shown in FIGS. Since it is very difficult to adjust the amount to an appropriate amount, the same problem as described above arises.

  In view of the above circumstances, the present invention makes it easy to fix each prism structure without causing any problems in optical characteristics, without providing a strict restriction on the amount of adhesive to be bonded and bonded together. And it makes it a technical subject to be able to stick appropriately.

  The present invention, which was created to solve the above technical problem, comprises a plurality of prism structures each having a basic shape of a triangular prism and the same or substantially the same refractive index. Are bonded to each other using an adhesive, and the four outer surfaces are each formed into a quadrangular prism shape connected via a corner portion, and at least one surface of the bonding surfaces has light depending on the wavelength component. In the light separating prism configured to transmit and reflect, a notch portion that leads to the bonding surface is formed at a portion where the bonding surface of the plurality of prism structures reaches the outer surface or the corner portion. The adhesive protruding from the bonding surface is solidified and attached to the notch in a state where it is accumulated. Here, “the refractive index is the same or substantially the same” means that the refractive index of the first prism component is slightly different from the refractive index of the second prism component, not only when they are completely the same. However, it is meant to include the case where they are substantially the same so that the following effects can be obtained. Furthermore, in order to “configure the light to be transmitted and reflected according to the wavelength component on the bonding surface”, a filter is provided on the surface of either one of the prism structures constituting the bonding surface. A film may be formed.

  According to such a configuration, the optimum amount of adhesive necessary to apply the amount of adhesive interposed between one surface or a plurality of surfaces of the plurality of prism structures to the bonding surface without excess or deficiency. If the amount is slightly larger than the amount, the adhesive is filled with the adhesive without generating space, voids or bubbles on the bonding surface, and the adhesive is at the end on the outer surface side or the corner portion side of the bonding surface. It will eat out from the department. In that case, since the notch part which leads to a bonding surface is formed in the part in which the bonding surface in this light separation prism has reached the outer surface or a corner part, the adhesive agent protruded from the bonding surface Remain in the notches and solidify and adhere to each other without interruption. Therefore, by setting the amount of adhesive that protrudes from the bonding surface to an amount that does not overflow from the notch to the outer surface or the corner, the adhesive that protrudes to the notch Since it can be stored and solidified, the adhesive surface is filled with the adhesive without causing a gap or the like, and the adhesive is bonded from the notch, without strictly adjusting the amount of the adhesive. The agent will not overflow and solidify on the outside. As a result, it is possible to avoid a situation in which an abnormal surface portion is generated on the optical path surface and light loss occurs, and the adhesive from the bonding surface to the notch becomes a continuous layer without interruption, so that bonding is performed from the outside. Water is prevented from entering the surface and water resistance is improved.

  In this case, it is preferable that the notch is formed by chamfering a corner of the prism structure.

  This configuration will be described in detail. The corners of one prism structure are chamfered, and the corners of the other prism structure are also chamfered, and the surfaces of the two prism structures are connected to each other. By combining them, a notch portion is formed between the chamfered portion of one prism component and the chamfered portion of the other prism component. According to this, the notch portion is formed by a simple operation of chamfering, and it is not necessary to separately form a notch portion. In this manner, the cutout portion can be communicated with the bonding surface.

  Moreover, it is preferable that the said notch part has comprised the cross section orthogonal to a pillar axis | shaft in the V shape which has a vertex part in the side edge part of the said bonding surface.

  If it does in this way, while a notch part exhibits a favorable function as a reservoir part of an adhesive agent, the formation operation of a notch part is facilitated.

  In this case, it is preferable that the notch portion has the V-shaped apex portion of 90 degrees or substantially 90 degrees.

  In this way, the notch can exhibit a further good function as a reservoir for the adhesive, and the volume of the solidified product of the adhesive can be optimized, so the degree of freedom in the amount of adhesive is sufficient. It is possible to make it larger.

  The adhesive is preferably an ultraviolet curable adhesive or a thermosetting adhesive.

  With this type of adhesive, not only can the above-mentioned effects be sufficiently obtained in relation to viscosity, solidification, etc., but it is also possible to easily perform the bonding operation of two prism components. Become.

  Furthermore, two prism structures are provided, and the two prism structures are bonded to each other using an adhesive, and the bonded surfaces of the two prism structures are fixed. The notch portions that lead to the bonding surface can be formed in the corner portions existing at the one side end and the other side end, respectively.

  In this way, the optimum amount of adhesive necessary to apply the amount of adhesive interposed between the bottom surface of one prism structure and the bottom surface of the other prism structure to the bonding surface without excess or deficiency. If the amount is slightly larger than the amount, the adhesive sticks out from one side end and the other side end of the bonding surface while ensuring proper filling of the adhesive. In that case, since the notch part which leads to a bonding surface is formed in the corner part which exists in the one side edge and other side edge of the bonding surface in this light separation prism, respectively, it protruded from the bonding surface. The adhesive remains in the notches and solidifies and adheres without interruption.

  In this case, it is preferable that the notch portion is formed by chamfering corner portions existing on both side ends of the bottom surfaces of the two prism structures.

  This configuration will be described in detail. Chamfering is performed on two corners on both sides of the bottom surface of one prism structure, and chamfering is performed on two corners on both sides of the bottom surface of the other prism structure. Then, by sticking the bottom surfaces of the two prism components together, a notch is formed between each chamfered portion of one prism component and each chamfered portion of the other prism component. .

  In this case, it is preferable that the notch is formed in a concave shape that is symmetrical on both sides with respect to the bonding surface.

  In this way, it is advantageous in that the adhesive that protrudes from the bonding surface is stored in the notch and does not overflow from the notch to the outer surface.

Furthermore, in the light separation prism in this case, the four outer surfaces include a first outer surface and a second outer surface that are adjacent to each other with a corner facing the bottom surface of the first prism structure as a boundary, and the second prism structure. A third outer surface and a fourth outer surface that are adjacent to each other with a corner portion facing the bottom surface as a boundary, and a boundary portion between the first outer surface and the fourth outer surface, and the second outer surface and the third outer surface. And the fourth outer surface is a surface that is bonded and fixed to the end surface of the ferrule to which the optical fiber is inserted and fixed, and the second outer surface. Is a surface on which light from the light emitting element is irradiated so as to be orthogonal, and the third outer surface is a surface from which light from the optical fiber reflected by the bonding surface exits orthogonally to the light receiving element side. The bonding surface is an optical It can be a surface having an inclination angle of the optical axis 45 degrees Bas. Note that the refractive indexes of the first and second prism structures are usually higher than the refractive index of an optical fiber made of SiO ₂ glass.

  In this way, the light from the light emitting element is directed in the direction perpendicular to the second outer surface of the light separation prism fixed to the end face of the ferrule to which the optical fiber is inserted and fixed. After passing through the outer surface and entering the inside, a predetermined wavelength component is transmitted through the bonding surface of the two prism components. In this case, since the refractive indexes of the two prism structures are the same or substantially the same, the light transmitted through the bonding surface travels straight and enters the optical fiber (core). On the other hand, light from the tip of the optical fiber passes through the fourth outer surface of the light separating prism and enters the inside, and a predetermined wavelength component different from the above is perpendicular to the bonded surface of the two prism structures. After being reflected so as to be bent, the light passes through the third outer surface and is received by a light receiving element such as an external photodiode. Thereby, the principal part of the optical communication system using this light separation prism is obtained.

  In this case, the angle formed between the bottom surface of the first prism structure and the second outer surface is formed at 45 degrees, and the angle formed between the bottom surface of the second prism structure and the third outer surface is 45. And the angle formed by the third outer surface and the fourth outer surface is preferably an obtuse angle.

  In this way, since the optical axis of the optical fiber and the fourth outer surface of the light separating prism are inclined without being orthogonal to each other, the light from the tip of the optical fiber is in contact with the fourth outer surface (the ferrule inclination). The generation of return light that is reflected in an inclined manner on the mating surface with the end face) and reverses along the optical axis of the optical fiber is suppressed. The light from the light emitting element (its optical axis) is transmitted through the second outer surface so as to be directed in a direction perpendicular to the second outer surface of the light separating prism and collinear with the optical axis of the optical fiber. Then, when entering the inside, light is not refracted, and after a predetermined wavelength component passes straight through the bonding surface of the two prism components, it is aligned with the optical axis of the optical fiber. Since the light is incident on the optical fiber (core) at a so-called 0 degree along the line, a decrease in coupling efficiency is appropriately suppressed, and a loss in optical transmission is significantly reduced. As a result, it is possible to obtain a light separation prism having appropriate characteristics in which return light is not generated and a decrease in coupling efficiency is suppressed.

  In this case, a filter film is preferably formed on the third outer surface.

  In this way, the light from the tip of the optical fiber travels in the light separating prism, is reflected by the bonding surface of the two prism constituents and bent at a right angle, and then in the second prism constituent When passing through the third outer surface, the wavelength region is selected a second time by the action of the filter film, and then received by the external light receiving element. As a result, the light that passes through the light separation prism from the tip of the optical fiber and reaches the light receiving element has a wavelength region that exactly matches the light receiving application.

  In this case, it is preferable that an antireflection film is formed on the first outer surface and the second outer surface.

  In this way, it is possible to prevent a situation in which the light irradiated from the light emitting element so as to be orthogonal to the second outer surface of the light separating prism is reflected and go back to the light receiving element, and the light from the light emitting element is It is also possible to cope with a case where it is necessary to avoid a situation in which the light is further reflected on the first outer surface after being reflected by the bonding surface in the light separation prism and is directed toward the light receiving element. In addition, since the antireflection film is formed on the two adjacent outer surfaces of the first prism structure, the film forming operation is completed by one batch process, and the two outer surfaces of the first prism structure are Even when they are bonded to the second prism structure in a state where they are interchanged with each other, the above-described antireflection effect can be appropriately obtained, so that the bonding operation can be simplified.

  On the other hand, in this case, a square whose basic shape is a quadrangular prism and whose refractive index is the same as or substantially the same as that of the prism structure is formed on one of the four outer surfaces provided with the two prism structures. Adhering and fixing one surface of the columnar prism structure using an adhesive, the square columnar prism structure is respectively formed with a missing portion that leads to both side ends of the bonded surface, It can be set as the structure which solidified and adhered to each connection part with one outer surface in the state which the adhesive agent which protruded from this bonding surface was collected.

  In this way, the above-mentioned adhesive accumulates at the connecting portion between the missing part of the prismatic prism structure and the outer surface of one of the prismatic bodies formed by bonding two prismatic prism structures together. In addition to the combination of prism structures in which the basic shape forms a triangular prism shape, the prisms in which the basic shape forms a quadrangular prism shape are used. Combination with a structure is also possible, and the present invention can be applied to various types of light separation prisms.

  In addition, as a manufacturing method of the light separation prism having the above configuration, it is preferable to use the following method. In other words, a plurality of original prism structures that are long in the column axis direction and have a basic shape of a triangular prism shape and are chamfered (in some cases, they are long in the column axis direction and have a basic shape of a square column shape) And a manufacturing process for manufacturing an original square prism-shaped prism structure having a missing portion (hereinafter the same), and a film forming process for forming a filter film or an antireflection film on a required surface of the plurality of original prism structures. A pasting step of manufacturing an original prism prism having four outer surfaces by bonding one or more surfaces of each of the plurality of original prism constituents with an adhesive; and the original prism prism in the column axis direction. And a cutting step of cutting at a plurality of locations.

  According to such a configuration, first, a plurality of original prism structures that are long in the column axis direction are manufactured, and after a filter film or an antireflection film is formed on these required surfaces, one of these is formed. Alternatively, a plurality of light separating prisms can be manufactured by cutting the original prismatic prism at a plurality of locations in the column axis direction by fabricating a prismatic prism by adhering and fixing a plurality of surfaces together with an adhesive. Obtainable. Thereby, compared with the case where the light separation prisms are manufactured individually by work, the work can be simplified and speeded up, and efficient mass production can be realized. In particular, when the light separation prism is small with a side length of 2 mm or less or several mm, the effect is sufficiently exerted. Even with such a method, the adhesive surface is solidified and adhered to a portion where the bonding surface of the light separation prism reaches the outer surface or the corner portion in a state where the adhesive is accumulated.

  As described above, according to the present invention, the adhesive necessary for applying the amount of the adhesive interposed between the one surface or the plurality of surfaces of the plurality of prism structures to the bonding surface without excess or deficiency. If the amount is slightly larger than the optimum amount, the adhesive will protrude from the end on the outer surface side or the corner portion side of the bonding surface. Since the notch part that leads to the bonding surface is formed in the part that has reached, the adhesive protruding from the bonding surface is accumulated in the notch part and solidified and attached. Become. Therefore, by setting the amount of adhesive that protrudes from the bonding surface to an amount that does not overflow from the notch to the outer surface or the corner, the adhesive that protrudes to the notch Since it can be stored and solidified, the adhesive surface is filled with the adhesive without causing a gap or the like, and the adhesive is bonded from the notch, without strictly adjusting the amount of the adhesive. The agent will not overflow and solidify on the outside. In addition, since the adhesive from the bonding surface to the notch becomes a continuous layer without interruption, water penetration from the outside to the bonding surface is prevented and water resistance is improved.

  Hereinafter, a light separation prism according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a single perspective view showing a light separation prism 1 according to the first embodiment of the present invention, and FIG. 2 is a schematic view showing a main part of an optical communication system configured using the light separation prism 1. It is a side view.

  As shown in FIGS. 1 and 2, the light separating prism 1 has a triangular prism shape and the first prism structure 2 and the second prism structure 3 having the same or substantially the same refractive index. By sticking together and adhering with an adhesive, it is formed into a quadrangular prism shape having four outer surfaces 2a, 2b, 3c, and 3d. More specifically, the light separating prism 1 includes a first outer surface 2a and a second outer surface 2b adjacent to each other with a corner 2x facing the bottom surface of the first prism structure 2 as a boundary, and a bottom surface of the second prism structure 3. It has the 3rd outer surface 3c and the 4th outer surface 3d which adjoin the corner | angular part 3y which faces each other as a boundary. The first outer surface 2a and the fourth outer surface 3d are formed adjacent to each other with the bonding surface 4 as a boundary, and the second outer surface 2b and the third outer surface 3c are bonded to the bonding surface 4. Are formed adjacent to each other as a boundary, and light is transmitted and reflected on the bonding surface 4 in accordance with the wavelength component. In addition, the material of the 1st prism structure 2 and the 2nd prism structure 3 in this light separation prism 1 is glass corresponding to BK-7 or BK-7.

  Further, the light separating prism 1 includes corner portions existing at one end and the other end of the bonding surface 4 of the two prism structures 2 and 3, that is, the first outer surface 2a and the fourth outer surface 3d. A notch 4x that communicates with the bonding surface 4 is formed at the boundary between the two and the boundary between the second outer surface 2b and the third outer surface 3c. One notch portion 4x includes a chamfered portion 2ax provided at a corner between the bottom surface of the first prism component 2 and the first outer surface 2a, a bottom surface of the second prism component 3, and a fourth outer surface. And the other notch 4x is chamfered at the corner between the bottom surface of the first prism component 2 and the second outer surface 2b. A portion 2bx and a chamfered portion 3cx formed at a corner portion between the bottom surface of the second prism constituting body 3 and the third outer surface 3c are formed. In this case, each chamfered portion 2ax, 2bx, 3cx, 3dx is formed as a surface that is perpendicular or substantially perpendicular to the corresponding outer surface 2a, 2b, 3c, 3d, and therefore the notch portion 4x is formed in the column axis direction. The cross-sectional shape orthogonal to the (aa direction) is a V shape having a vertex (bottom) of 90 degrees or substantially 90 degrees at the side end of the bonding surface 4.

  The adhesive S protruding from the bonding surface 4 is solidified and attached to both the notches 4x over the entire length in the column axis direction. The adhesive S accumulated in both of the notch portions 4x is solidified without overflowing any outer surface 2a, 2b, 3c, 3d from the notch portion 4x. Therefore, in this embodiment, The adhesion surface of the solidified material of the adhesive S is not the entire surface of the notch 4x, but a partial surface continuous in the column axis direction on the apex side. In this case, an ultraviolet curable adhesive or a thermosetting adhesive is used as the adhesive S for bonding the two prism constituent bodies 2 and 3 together.

  In this embodiment, the angle of the corner 2x facing the bottom surface (bonding surface 4) of the first prism structure 2 is formed at 90 degrees, and the bottom surface of the first prism structure 2 and the first The angle between the outer surface 2a and the angle between the bottom surface and the second outer surface 2b are both 45 degrees. In addition, the angle formed between the bottom surface (bonding surface 4) of the second prism structure 3 and the third outer surface 3c is formed at 45 degrees, and the third outer surface 3c and the second outer surface 3c of the second prism structure 3 are formed. The angle α formed by the four outer surfaces 3d is formed to be an obtuse angle of more than 90 degrees and 100 degrees or less. Therefore, the angle β formed by the bottom surface of the second prism constituting body 3 and the fourth outer surface 3d is less than 45 degrees and 35 degrees or more.

  Further, a filter film that transmits light in a predetermined wavelength region is formed on the bottom surface of either one of the two prism constituent bodies 2 and 3 in the light separating prism 1, whereby the prism constituent bodies 2 and 3 have The bonding surface 4 transmits and reflects light according to the wavelength component, and a filter film that transmits light in a wavelength region different from the above is formed on the third outer surface 3 c of the second prism structure 3. Has been. Further, an antireflection film is formed on the first outer surface 2 a and the second outer surface 2 b of the first prism structure 2.

  As shown in FIG. 2, the fourth outer surface 3 d of the light separating prism 1 has a ferrule 6 in which an optical fiber 5 having a lower refractive index than the first and second prism constituent bodies 2 and 3 is inserted and fixed. Attached to the inclined end surface 6a using an ultraviolet curable adhesive or a thermosetting adhesive, and the second outer surface 2b is such that the light X projected from the light emitting element 7 such as a laser diode is orthogonal to the second outer surface 2b. The surface is arranged so as to be orthogonal to the optical axis of the optical fiber 5. The bonding surface 4 of the two prism constituent bodies 2 and 3 is inclined at an angle of 45 degrees with respect to the optical axis of the optical fiber 5 and the light X from the light emitting element 7, and the third outer surface 3c is The light Y emitted from the optical fiber 5 and reflected by the bonding surface 4 and bent at a right angle is a surface through which the light Y passes orthogonally, and the light Y is received by the light receiving element 8 such as a photodiode. ing.

  According to such a configuration, it is necessary to apply the amount of adhesive interposed between the bottom surface of the first prism structure 2 and the bottom surface of the second prism structure 3 to the bonding surface 4 without excess or deficiency. If the amount is slightly larger than the optimum amount of the adhesive, the adhesive is filled with the adhesive without causing a space or a gap on the bonding surface 4, and the adhesive is on one side end and the other side of the bonding surface 4. It will eat out from the edge. In that case, since the notch part 4x which leads to the bonding surface 4 is each formed in the corner part which exists in the one side end and other side end of the bonding surface 4 in this light separation prism 1, the bonding surface 4 The adhesive S that protrudes from the surface stays in the notches 4x and is solidified and attached without interruption. In addition, if the amount of the adhesive S that protrudes from the bonding surface 4 is set to an amount that does not overflow from the notch 4x to the outer surfaces 2a, 2b, 3c, and 3d, It can be stored and solidified only around the apex portion of the notch 4x. Thereby, without strictly adjusting the amount of the adhesive, the bonding surface 4 is filled with the adhesive without causing a space or the like, and the outer surfaces 2a, 2b, The adhesive will not overflow and solidify in 3c and 3d.

  Further, according to the light separation prism 1 according to this embodiment, since the optical axis of the optical fiber 5 and the fourth outer surface 3d are inclined, a part of the light from the tip of the optical fiber 5 is The light y is reflected in an inclined manner at the mating surface with the four outer surfaces 3d or the inclined end surface 6a of the ferrule 6, and no return light traveling backward on the optical axis of the optical fiber 5 is generated, which may induce noise. It is possible to reduce the functional failure on the optical transmission. Further, since the light X from the light emitting element 7 is directed in a direction perpendicular to the second outer surface 2b of the light separating prism 1 and along the same straight line as the optical axis of the optical fiber 5, When the light passes through the outer surface 2b and enters the inside, light is not refracted. Further, the light X from the light emitting element 7 travels through the light separating prism 1, passes through the bonding surface 4 of the two prism structures 2 and 3, and then enters the optical axis (core) of the optical fiber 5. On the other hand, since it is incident at a so-called 0 degree, a decrease in coupling efficiency is appropriately suppressed, and a loss of optical transmission is remarkably reduced.

  Since the antireflection film is formed on the second outer surface 2b of the light separating prism 1, the light X from the light emitting element 7 is irradiated perpendicularly to the second outer surface 2b. The problem that the light X goes backward toward the light emitting element 7 is avoided. Further, since the antireflection film is also formed on the first outer surface 2a of the light separating prism 1, the light X from the light emitting element 7 is further reflected after being reflected by the bonding surface 4 of the light separating prism 1. It is also possible to avoid a problem that the light is reflected by the one outer surface 2a and travels toward the light receiving element 8 side.

  Next, a method for manufacturing the light separation prism 1 having the above-described configuration will be described. First, as shown in FIG. 3A, a triangular prism shape having chamfered portions 2ax, 2bx, 3cx, and 3dx having the same cross-sectional shape as the first and second prism constituent bodies 2 and 3 is formed in the column axis direction. Two long original prism structures 2X and 3X are manufactured. Then, a filter film is formed on the entire surface corresponding to one of the bottom surfaces of these two original prism structures 2X and 3X and the entire surface corresponding to the third outer surface 3c, respectively, and the first An antireflection film is formed on the entire surface corresponding to the outer surface 2a and the second outer surface 2b. These films are formed by sputtering or vapor deposition in a state where a plurality of original prism structures 2X and 3X are set in a dedicated film forming jig. Thereafter, as shown in FIG. 4B, the base prism prism 1X having four outer surfaces is obtained by bonding the bottom surfaces of the two original prism structures 2X and 3X with an ultraviolet curable or thermosetting adhesive. To manufacture. As a result, notch portions 4x extending over the entire length in the column axis direction are respectively formed at both side ends of the bonding surface 4 of the original prismatic prism 1X, and the notch portions 4x are continuously provided over the entire length. The adhesive S is collected and solidified and attached. Thereafter, as shown in FIG. 5C, the original prism prism 1X is cut at a plurality of locations in the column axis direction to obtain a plurality of light separating prisms 1.

  FIG. 4 illustrates the light separation prism 1 according to the second embodiment of the present invention. The light separation prism 1 according to the second embodiment differs from the light separation prism 1 according to the first embodiment described above in the column axis direction of the first prism structure 2 and the second prism structure 3. The basic shape of the cross section orthogonal to is an isosceles right triangle. Since the other configuration is the same as that of the first embodiment described above, the same reference numerals are assigned to the common configuration requirements for both, and the description thereof is omitted. And according to this 2nd embodiment, the effect similar to the above-mentioned 1st embodiment is acquired regarding the point which has solidified and adhered in the state which the adhesive agent S was stored in the notch part 4x. .

  FIG. 5 illustrates the light separation prism 1 according to the third embodiment of the present invention. The light separating prism 1 according to the third embodiment differs from the first embodiment described above in that the angle formed between the bottom surface of the first prism structure 2 and the second outer surface 2b is 45 degrees. In addition, the angle of the corner portion 2x facing the bottom surface is an acute angle instead of 90 degrees. Since the other configuration is the same as that of the first embodiment described above, the same reference numerals are assigned to the common configuration requirements for both, and the description thereof is omitted. According to the third embodiment, the adhesive S is solidified and attached to the notch 4x, and the generation of return light and the reduction of coupling efficiency are suppressed. In addition to obtaining the same operational effects as those of the first embodiment described above, when the light from the light emitting element is reflected by the bonding surface 4 and further reflected by the first outer surface 2a, Since it does not pass through the outer surface 3c orthogonally and does not go to the light receiving element, it is possible to obtain an advantage that it is not necessary to form an antireflection film on the first outer surface 2a.

  FIG. 6 illustrates the light separation prism 1 according to the fourth embodiment of the present invention. The light separating prism 1 according to the fourth embodiment differs from the first embodiment described above in that the angle formed between the bottom surface of the first prism structure 2 and the second outer surface 2b is 45 degrees. In addition, the angle of the corner portion 2x facing the bottom surface is not 90 degrees but an obtuse angle. Since the other configuration is the same as that of the first embodiment described above, the same reference numerals are assigned to the common configuration requirements for both, and the description thereof is omitted. According to the fourth embodiment, the point that the adhesive S is solidified and attached to the notch 4x and the point that the return light is prevented from being generated and the coupling efficiency is prevented from being lowered are also described. In addition to obtaining the same operational effects as those of the first embodiment, the first outer surface 2a is further reflected after the light from the light emitting element is reflected by the bonding surface 4, as in the third embodiment. When the light is reflected at the surface, it does not pass through the third outer surface 3c orthogonally and does not go to the light receiving element, so that it is not necessary to form an antireflection film on the first outer surface 2a. Can do.

  FIG. 7 illustrates a light separation prism 1 according to the fifth embodiment of the present invention. The light separating prism 1 according to the fifth embodiment differs from the first embodiment described above in that the angle formed by the first outer surface 2a and the second outer surface 2b in the first prism structure 2 is the same. The angle formed between the third outer surface 3c and the fourth outer surface 3d of the second prism structure 3 is also an obtuse angle, and the cross-sectional shape of both prism structures 2, 3 is an isosceles triangle. As a result, a quadrangular prism shape (a cross-sectional shape perpendicular to the column axis is a parallelogram) is formed on the third outer surface 3c of the second prism constituting body 3 in that the cross-sectional shape perpendicular to the column axis exhibits a parallelogram. The third prism structure 14 forming the above is bonded and fixed using the same adhesive as described above, thereby forming a quadrangular prism shape (a cross section perpendicular to the column axis is a parallelogram) as a whole. It is. The third prism structure 14 is formed with a notch (missing part) 14x leading to both side ends of the bonding surface 3c, and the one (right) missing part 14x and the second prism structure 3 are formed. A rectangular groove-like concave portion is formed from the exposed portion of the third outer surface 3c in FIG. 5, and the other (left side) missing portion 14x and the chamfered portion 3cx of the second prism structure 3 are flush with each other. A rectangular groove-like concave portion is formed in which the missing portion 14x and the cutout portion 4x are continuous. In this configuration, the adhesive that protrudes from the bonding surface 3 c to the connecting portions 14 y of the two missing portions 14 x of the third prism structure 14 and the third outer surface 3 c of the second prism structure 3. In a state where S is accumulated, it is solidified and attached. Therefore, also in the fifth embodiment, the same effects as those in the first embodiment described above are obtained in that the adhesive S is solidified and adhered to the notch portion 4x and the connecting portion 14y. Is obtained. In addition, the manufacturing method of the light separating prism 1 according to the fifth embodiment is basically the same as that already described with reference to FIG. 3, but in this case, a triangular prism shape having a chamfered portion is formed. In addition, two original prism structures that are long in the column axis direction and one original prism structure that has a rectangular column shape having a missing part and is long in the column axis direction are manufactured. After forming a filter film and anti-reflection film on the required surface of the structure, the original prism prism having four outer surfaces is manufactured by bonding the three original prism structures together with an ultraviolet-curing or thermosetting adhesive. To do. As a result, a notch portion and a connecting portion are formed in the original prismatic prism over the entire length in the column axis direction, and the adhesive S is continuously formed over the entire length of the notch portion and the connecting portion. Is accumulated and solidified and attached. Thereafter, by cutting the original prism prism at a plurality of locations in the column axis direction, a plurality of light separation prisms 1 can be obtained. In the light separation prism 1 according to the fifth embodiment, the light indicated by the symbol A in the figure travels straight, but the light denoted by the symbol B travels straight after being partially reflected by the bonding surface 4. On the other hand, the remaining part is further reflected by the bonding surface 3 c and the bonding surface 4 as indicated by the symbol C.

  FIG. 8 illustrates a light separation prism 1 according to the sixth embodiment of the present invention. The light separating prism 1 according to the sixth embodiment differs from the first embodiment described above in that four outer surfaces are constituted by the bottom surfaces 15a of the four triangular prism-shaped prism structures 15, The two surfaces excluding the bottom surface 15a of the prism structure 15 are fixed to each other with the same adhesive as described above to form four bonding surfaces 16, 17, 18, 19 and the four bonding surfaces. The notch part 15x is formed in each part where the mating surfaces 16, 17, 18, and 19 reach the corner part. In this case, a total of four notches 15x are respectively formed by a pair of chamfered portions 15c formed at both ends of the bottom surface 15a of the four prism structures 15 and adjacent to each other. Also in the sixth embodiment, the same effects as those in the first embodiment described above can be obtained with respect to the point that the adhesive S is solidified and adhered to the notch 15x. Further, the manufacturing method of the light separating prism 1 according to the sixth embodiment is basically the same as that already described with reference to FIG. 3, but in this case, a triangular prism shape having a chamfered portion is formed. In addition, four original prism structures that are long in the column axis direction are manufactured, a filter film and an antireflection film are formed on a required surface of these four original prism structures, and then four original prism structures are formed. Are bonded together with an ultraviolet curable or thermosetting adhesive to produce a prismatic prism having four outer surfaces. As a result, notches are formed in the four corners of the original prism prism over the entire length in the column axis direction, and the adhesive S is continuously accumulated in these notches over the entire length. It becomes solidified and adheres. Thereafter, by cutting the original prism prism at a plurality of locations in the column axis direction, a plurality of light separation prisms 1 can be obtained. In the light separating prism 1 according to the sixth embodiment, a part of the light goes straight as indicated by the symbol D, but the remaining part is reflected by the bonding surface 17 as indicated by the symbol E. The remaining part is reflected by the bonding surface 18 as indicated by reference numeral F.

  FIG. 9 illustrates a light separation prism 1 according to the seventh embodiment of the present invention. The light separation prism 1 according to the seventh embodiment is different from the first embodiment described above in that two light separation prisms 1 are provided on two surfaces excluding the bottom surface of the single triangular prism-shaped prism structure 20 existing in the center. One surface of the prism-shaped prism-shaped body 21 is fixed with an adhesive similar to the above to form two bonding surfaces 22 and 23. In this case, among the chamfered portions 20c formed at the three corners of the central prism structure 20, and the chamfered portions 21c formed at the two corners of the two prism structures 21 on both sides, A notch portion 24x is formed by a pair of chamfered portions 20c and 21c at adjacent positions. More specifically, a notch portion 24x is formed in each of two corner portions and one outer surface of a quadrangular columnar body made up of three prism structures 20, 21, and 21, and two outer portions are divided into two parts. A rectangular groove-like recess is formed by the two notches 24x. Also according to the seventh embodiment, the same effects as those of the first embodiment described above can be obtained with respect to the point that the adhesive S is solidified and attached to the notch 22x. Further, the manufacturing method of the light separating prism 1 according to the seventh embodiment is basically the same as that already described with reference to FIG. 3, but in this case, a triangular prism shape having a chamfered portion is formed. In addition, three original prism structures that are elongated in the column axis direction are manufactured, and after a filter film and an antireflection film are formed on a required surface of these three original prism structures, the three original prism structures are formed. Are bonded together with an ultraviolet curable or thermosetting adhesive to produce a prismatic prism having four outer surfaces. As a result, a notch extending over the entire length in the column axis direction is formed on each of the two corners and one outer surface of the original prism prism, and the notches are continuously bonded to these notches. The agent S is accumulated and solidified and attached. Thereafter, by cutting the original prism prism at a plurality of locations in the column axis direction, a plurality of light separation prisms 1 can be obtained. In the light separating prism 1 according to the seventh embodiment, a part of the light travels straight as indicated by the symbol G, but the remaining part is reflected by the bonding surface 22 as indicated by the symbol H. The remaining part is reflected by the bonding surface 23 as indicated by symbol I.

It is a single-piece | unit perspective view which shows the light separation prism which concerns on 1st embodiment of this invention. It is a schematic side view which shows the principal part of the optical communication system comprised using the light separation prism which concerns on 1st embodiment of this invention. FIGS. 3A, 3B, and 3C are schematic perspective views showing a manufacturing procedure of the light separation prism according to the first embodiment of the present invention. It is a schematic side view which shows the principal part of the optical communication system comprised using the light separation prism which concerns on 2nd embodiment of this invention. It is a schematic side view which shows the principal part of the optical communication system comprised using the light separation prism which concerns on 3rd embodiment of this invention. It is a schematic side view which shows the principal part of the optical communication system comprised using the light separation prism which concerns on 4th embodiment of this invention. It is a schematic side view which shows the light separation prism which concerns on 5th embodiment of this invention. It is a schematic side view which shows the light separation prism which concerns on 6th embodiment of this invention. It is a schematic side view which shows the light separation prism which concerns on 7th embodiment of this invention. It is a schematic side view which shows the principal part of the optical communication system comprised using the light separation prism which concerns on the conventional 1st example. It is a schematic side view which shows the light separation prism which concerns on the conventional 2nd example. It is a schematic side view which shows the light separation prism which concerns on the conventional 3rd example. It is a schematic side view which shows the light separation prism which concerns on the conventional 4th example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light separation prism 2 Prism structure (1st prism structure)
2a First outer surface 2ax Chamfer 2b Second outer surface 2bx Chamfer 3 Prism structure (second prism structure)
3c Third outer surface 3cx Chamfering 3d Fourth outer surface 3dx Chamfering 4 Bonding surface 4x Notch 5 Optical fiber 6 Ferrule 6a Ferrule end surface 7 Light emitting element 8 Light receiving element 14 Square prismatic prism structure (third prism structure)
14x missing part (notch part)
14y connecting portion 15 prism structure 15c chamfer 15x notch 16 bonding surface 17 bonding surface 18 bonding surface 19 bonding surface 20 prism structure 20c chamfering portion 21 prism structure 21c chamfering portion 22 bonding surface 23 bonding Matching surface 24x Notch S Adhesive X Light from light-emitting element Y Light from optical fiber Return light

Claims (13)

A plurality of prism structures having a basic prism shape and the same or substantially the same refractive index are bonded to each other using an adhesive, and fixed. In the light separation prism configured such that two outer surfaces are formed in a quadrangular prism shape that is continuous via a corner portion, and light is transmitted and reflected according to a wavelength component on at least one surface of the bonding surface,
A notch portion that communicates with the bonding surface is formed at a portion where the bonding surfaces of the plurality of prism structures reach the outer surface or the corner portion, and the cut surface is cut from the bonding surface. A light separation prism characterized in that the protruding adhesive is solidified and adhered in a state where it is stored.   2. The light separating prism according to claim 1, wherein the notch is formed by chamfering a corner of the prism structure. 3.   3. The light separation according to claim 1, wherein the cutout portion has a V-shaped cross-section perpendicular to the column axis and having an apex portion at a side end portion of the bonding surface. prism.   The light splitting prism according to claim 3, wherein the notch has a V-shaped apex portion of 90 degrees or substantially 90 degrees.   The light separating prism according to claim 1, wherein the adhesive is an ultraviolet curable adhesive or a thermosetting adhesive.   Two prism structures are provided, and the two prism structures are bonded and bonded to each other using an adhesive, and one side of the bonding surface of the two prism structures 6. The light separating prism according to claim 1, wherein the cutout portion that communicates with the bonding surface is formed at each corner portion at the end and the other end.   The light splitting prism according to claim 6, wherein the notch portion is formed by chamfering corner portions existing on both side ends of the bottom surfaces of the two prism structures.   8. The light separating prism according to claim 6, wherein the notch is formed in a concave shape that is symmetrical on both sides with respect to the bonding surface.   The four outer surfaces are adjacent to each other with a first outer surface and a second outer surface adjacent to each other as a boundary at a corner portion facing the bottom surface of one prism component, and a corner portion facing a bottom surface of the other prism component member as a boundary. Each of the first outer surface and the fourth outer surface, and the boundary portion between the second outer surface and the third outer surface, the notch portions respectively. The fourth outer surface is formed and bonded to the end surface of the ferrule to which the optical fiber is inserted and fixed, and the second outer surface is formed so that the light from the light emitting element is orthogonal to the second outer surface. The third outer surface is a surface from which light from the optical fiber reflected by the bonding surface exits perpendicularly to the light receiving element side, and the bonding surface is an optical axis of the optical fiber. And a surface with an inclination angle of 45 degrees Light separation prism according to any one of claims 6-8, characterized.   The angle formed between the bottom surface of the one prism structure and the second outer surface is formed at 45 degrees, and the angle formed between the bottom surface of the other prism structure and the third outer surface is formed at 45 degrees, The light separating prism according to claim 9, wherein an angle formed by the third outer surface and the fourth outer surface is an obtuse angle.   The light separation prism according to claim 9 or 10, wherein a filter film is formed on the third outer surface.   The light separation prism according to any one of claims 9 to 11, wherein an antireflection film is formed on the first outer surface and the second outer surface.   A quadrangular prism-shaped prism structure having a basic shape of a quadrangular prism and a refractive index that is the same as or substantially the same as that of the prism structure on one outer surface of the four outer surfaces including the two prism structures. One surface is bonded and fixed using an adhesive, and a missing portion that leads to both ends of the bonded surface is formed in each of the prismatic prism structures, and the missing portion and the one outer surface The light separating prism according to any one of claims 6 to 8, wherein an adhesive protruding from the bonding surface is solidified and attached to each connecting portion.

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