JP2018036637A - Lens array, fiber ray module and light reception module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens array that can maintain a proper interval without increasing the number of components, and processing steps.SOLUTION: The present disclosure is a lens array that comprises: a plurality of aspherical lenses 23 that is held in a flat holding surface 24A, and has a central axis Aof the aspherical lens 23 parallely arranged in a prescribed plane surface Pvertical to the holding surface 24A; a lens holding part 24 that holds the plurality of aspherical lenses 23 on the holding surface 24A; and a plurality of spacers 22 that is arranged in the holding surface 24A, and has a vertex surface 22A at a position where a height from the holding surface 24A is higher than the plurality of aspherical lenses 23, in which each vertex surface 22A provided in the spacer 22 is inclined at an equal prescribed angle relative to the holding surface 24A vertical to the optical axis Aof the aspherical lens 23.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a lens array, a fiber array module, and a light receiving module.

  A light receiving module for WDM transmission has been proposed (see, for example, Patent Document 1). The light receiving module of Patent Document 1 collimates a beam emitted from a fiber array with a lens array, branches a part of the beam with a beam splitter bar, and monitors a light in a transmission path, and installs a PD installed in a subsequent stage. Receive light at. The light reflected by the beam splitter bar is returned to the optical fiber through the lens array.

  In order to return the light reflected by the beam splitter bar to the optical fiber, the light receiving module of Patent Document 1 needs to appropriately maintain the distance between the optical fiber and the lens and the distance between the lens array and the beam splitter.

  On the other hand, a technique for maintaining an appropriate distance from the lens array has been proposed (see, for example, Patent Document 2). In Patent Document 2, a spacer suitable for the distance between the optical fiber and the lens array, a transparent member suitable for the distance between the lens array and the optical filter, a spacer suitable for the distance between the optical filter and the photodiode, and a transparent member are sequentially arranged. Then, pass the guide pins through them and fix them with the tightening mechanism from the outside.

JP 2009-093131 A JP 2005-037662 A JP-A-3-131803

  The technique of Patent Document 2 requires a transparent member and a spacer, and thus has a problem that the number of parts increases. In addition, the technique of Patent Document 2 requires a guide hole for each component including the spacers, and also requires a mechanism for fastening and fixing the whole, so that there is a problem that the number of processing steps increases.

  Therefore, an object of the present disclosure is to provide a lens array capable of maintaining an appropriate interval without increasing the number of parts and the processing steps.

The lens array of the present disclosure includes:
A plurality of aspheric lenses that are held by a flat holding surface and in which a central axis of the lens is arranged in parallel in a predetermined plane perpendicular to the holding surface;
A lens holding unit for holding the plurality of aspheric lenses on the flat holding surface;
A plurality of convex portions arranged on the holding surface and having convex surfaces at positions higher than the plurality of aspheric lenses from the holding surface;
With
Each convex surface provided in the plurality of convex portions is inclined at a predetermined angle equal to a surface perpendicular to the optical axis of the aspheric lens.

The lens array of the present disclosure includes:
A plurality of aspheric lenses that are held by a flat holding surface and in which a central axis of the lens is arranged in parallel in a predetermined plane perpendicular to the holding surface;
A lens holding unit for holding the plurality of aspheric lenses on the flat holding surface;
A plurality of convex portions arranged on the holding surface and having convex surfaces at positions higher than the plurality of aspheric lenses from the holding surface;
With
Each convex surface provided in the plurality of convex portions is parallel to a surface perpendicular to the optical axis of the aspheric lens,
A back surface of the holding portion facing the convex surface is inclined at a predetermined angle equal to a surface perpendicular to the optical axis of the aspheric lens.

The fiber array module of the present disclosure includes:
Each of the two optical fibers has one aspheric lens, and each of the aspheric lenses condenses light from the two optical fibers on one point of a reflection surface defined for each of the aspheric lenses. A first lens array of the present disclosure;
Each of the aspheric lenses included in the first lens array has two optical fibers, and the longitudinal direction of each optical fiber is arranged in parallel to the central axis of the aspheric lens within the predetermined plane. Fiber array
Is provided.

The fiber array module of the present disclosure includes:
Forming a reflecting surface of each of the aspherical lenses, transmitting a part of the light condensed at the one point, and reflecting a part of the light condensed at the one point;
Light having a plurality of through holes that transmit the light transmitted from the partial transmission film, and each light transmitted from the partial transmission film is incident on one end of the different through holes, and the light after passing through the through holes An optical component that emits from the other end of each through-hole,
A second lens array for condensing each light emitted from the other end of the plurality of through holes at a point determined for each through hole;
May be further provided.
Here, a GRIN lens may be disposed in the through hole, and the second lens array may be omitted. In this case, the optical component condenses at a condensing point determined by the GRIN lens.

  The light receiving module of the present disclosure includes a fiber array module according to the present disclosure and a light receiving element array.

  According to the present disclosure, it is possible to provide a lens array capable of maintaining an appropriate interval without increasing the number of parts and the processing steps.

The structural example of the fiber array module which concerns on 1st Embodiment is shown. It is a 1st example of the lens array which concerns on 1st Embodiment. It is a 2nd example of the lens array which concerns on 1st Embodiment. It is a schematic diagram of a glass mold process. It is an example of the optical fiber lens optical system of 1st Embodiment. It is an example of the parameter in 1st Embodiment. The structural example of the fiber array module which concerns on 2nd Embodiment is shown. It is a 1st example of the lens array which concerns on 2nd Embodiment. It is a 2nd example of the lens array which concerns on 2nd Embodiment. It is an example of the optical fiber lens optical system of 2nd Embodiment. It is an example of the parameter in 2nd Embodiment. An example of the fiber array module which concerns on 3rd Embodiment is shown. An example of the light reception module which concerns on 3rd Embodiment is shown. An example of the fiber array module which concerns on 4th Embodiment is shown. An example of the light reception module which concerns on 4th Embodiment is shown. An example of the connection surface seen from the z direction of the fiber array in 5th Embodiment is shown. An example of the structure seen from the x direction of the light reception module in 5th Embodiment is shown. An example of the enlarged view of the fiber array and lens array which concern on 3rd Embodiment is shown. The other example of the fiber array module which concerns on 3rd Embodiment is shown. The other example of the light reception module which concerns on 3rd Embodiment is shown. The other example of the fiber array module which concerns on 3rd Embodiment is shown.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, this indication is not limited to embodiment shown below. These embodiments are merely examples, and the present disclosure can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(First embodiment)
FIG. 1 shows a configuration example of the fiber array module according to the present embodiment. The fiber array module according to this embodiment includes a lens array 2 in which a plurality of aspherical lenses 23-1 to 23-4 are arranged, and a fiber array 1 in which a plurality of optical fibers 11A and 11B are arranged. Prepare. Fiber array 1 and the lens array 2 has four fibers - shows an example of a lens optical system, are arranged in parallel on a predetermined plane P _C.

Each aspherical lens 23 provided in the lens array 2 includes a fiber-lens optical system as a basic unit. The optical axis A _C is the center axis of each aspherical lens is arranged in parallel in a predetermined plane P _C. The fiber array 1 has two optical fibers 11A and 11B for each aspheric lens 23-1 to 23-4.

  2 and 3 show examples of the configuration of the lens array. The lens array 2 according to the present embodiment includes a plurality of aspherical lenses 23, a lens holding unit 24, and a plurality of spacers 22 for maintaining an appropriate interval. The lens array 2 in FIG. 2 includes two spacers 22-1 and 22-2, and the lens array 2 in FIG. 3 includes four spacers 22-1, 22-2, 22-3, and 22-4. The area of the plurality of spacers 22 is preferably larger than the projected area of the aspherical lens 23 onto the lens holding surface 24.

The lens holding unit 24 holds a plurality of aspheric lenses 23 on a flat lens holding surface 24A. Aspheric lens 23 is held in a flat lens holding surface 24A, the central axis A _C of the aspheric lens 23 are arranged in parallel to the lens holding surface 24A perpendicular predetermined plane P _C. In the example of FIG. 2, an aspherical lens 23 having the x-axis direction as the array direction is formed on a lens holding surface 24A parallel to the xy plane.

The plurality of spacers 22 are arranged on both sides of the lens holding surface 24A in the x-axis direction, which is the arrangement direction of the plurality of aspheric lenses 23, so as to be adjacent to the aspheric lenses 23-1 and 23-4. Yes. For example, in FIG. 2, while _{S 22, 23} of the aspherical lens 23-1 and the spacer 22-1, between _{S 22, 23} of the aspherical lens 23-4 and the spacer 22-2, parallel to the y direction in FIG. As indicated by a dotted line, it is preferable that a flat portion is secured on the lens holding surface 24A. Thereby, at the time of connection work with the fiber array 1, the positional relationship between the fiber array 1 and the entire lens array 2 can be confirmed by observing from the y direction in the figure.

  In addition, the plurality of spacers 22 are arranged outside both ends of the plurality of aspheric lenses 23 in the y direction orthogonal to the arrangement direction of the plurality of aspheric lenses 23 in the lens holding surface 24A. For example, as shown in FIG. 3, when viewed from the x direction, the shape of the spacer 22 is such that only the projected portion in the x direction is scraped so that the entire aspherical lens 23 looks the same as from the y axis direction. It is preferable that Thereby, at the time of connection work with the fiber array 1, the positional relationship between the optical fiber and the aspherical lens 23 can be confirmed not only from the y direction but also from the x direction.

The spacer 22 of this embodiment is formed integrally with the lens array 2. For this reason, it is possible to maintain an appropriate distance between the fiber array 1 and the lens array 2 without increasing the number of parts and without increasing the number of processing steps. In this case, since the spacer 22 is processed simultaneously with the recess processing of the lens array 2, the side wall of the spacer 22 is curved at the curvature radius R ₂₂ of the recess processing of the lens array 2. The radius of curvature _{R 22} is, for example, 150 [mu] m.

The spacer 22 has a convex surface, that is, a top surface 22A at a position where the height from the lens holding surface 24A is higher than the plurality of aspherical lenses 23. The rear surface 24B of the lens array 2 is parallel to the lens holding surface 24A, and the partial transmission film 4 is attached thereto. Each top surface 22A is inclined at a predetermined angle equal with respect to a plane perpendicular to the optical axis A _C of the aspheric lens 23. In the example of FIG. 2, the distance between the intersection line of the top surface 22A of the spacer 22 with the plane (surface parallel to the xz plane) formed by the lens optical axis array and the apex of the aspherical lens 23 is the convexity shown in FIG. In this state, the top surface 22A is inclined at a predetermined angle with respect to the xy plane in accordance with the inclination of the end surface of the fiber array 1. The predetermined angle is about 8 degrees, for example, not less than 7 ° and not more than 9 °. The predetermined angle is not limited to 8 degrees.

  FIG. 4 shows an example of manufacturing the lens array 2. The lens array 2 according to the present embodiment can be manufactured using a glass mold process. Between the piston-shaped upper mold 53 made of stainless steel (SUS304) or the like and the lower mold 54 in which the concave portion having the shape of the spacer 22 is dug together with the lens shape, a raw material glass lump 55 having a desired finished volume is formed. It is sandwiched and pressed at a high temperature above the yield point in a vacuum. As a matter of course, in the lower mold shape, the concave portion for the spacer 22 is deeper than the lens array 2.

When the raw glass lump is pressed, the raw material flows into the recess for the spacer 22 and the lower mold shape is transferred to the glass bowl 55. In order to ensure the ease of movement of the raw material in the pressing process. The depth d _s of the recess for the spacer 22 is preferably shallower than the flat portion thickness t _b of the lens array 2. If the movement of the raw material in the pressing process is insufficient, even if the concave portion is apparently filled without a gap, a large shape error or cracking due to residual stress may occur after cooling. If the depth d _s of the concave portion for the spacer 22 is made shallower than the thickness t _b of the flat portion of the lens array 2, the material movement in the pressing process is sufficiently spread, and it is possible to prevent occurrence of shape errors and cracks after cooling. it can.

FIG. 5 shows a first fiber-lens optical system according to this embodiment. Hereinafter, the directions will be described following the orthogonal xyz coordinate axes in the drawing. The left side of the figure, in the xz plane, is parallel to the z-axis, the fiber array 1 arranged with the optical fiber 11A and 11B with equal fiber spacing d _f in the x-axis direction is disposed. The fiber array 1 is configured to be held by a housing such as Tempax glass with a plane parallel to the x-axis and forming a predetermined angle with respect to the y-axis as an end surface.

On the right side of the figure, an aspheric lens 23 fiber spacing in the x-axis direction as a common plane plane perpendicular to the z axis is the optical axis direction d _f times the spacing 2d _f having an optical axis parallel to the z-axis An array is formed, and the convex side of the air layer 3 is arranged with a predetermined distance, which will be described later, facing the fiber array 1. The thickness of the lens holding surface 24A and the back surface 24B, the distance between the aspherical lens 23 and the back surface 24B is set to match the concave side focal length f _c shown in FIG.

The relative position of the fiber array 1 and the lens array 2, x-axis direction, the center line (this figure the optical fibers to the optical axis A _C of the aspheric lens 23 is adjacent the fiber array 1, the optical fiber 11A and the optical fiber to match 11B centerline of), y-direction, each optical fiber 11A-1~11A-4 and the optical axis _{a C} array formed plane of the facilities in the fiber array 1 of the aspherical lens 23 11b- to match the 1~11B-4 plane P _C formed at the centerline, and z directions, the distance between the convex vertices of the end surface and the lens array 2 of the fiber array 1 is convex-side focal point of the aspheric lens 23 It is set so as to match the distance f _v. A partial transmission film 4 having a function of reflecting / transmitting light of a predetermined wavelength at a desired ratio is attached to the surface on the back surface 24B side of the lens array 2 which is the right end in FIG. In such a configuration, the path of light emitted from the end face P1 of the optical fiber 11A will be considered by light ray approximation.

Since the end face P1 of the optical fiber 11A is located on the convex focal plane, the light emitted from the end face of the optical fiber 11A as a point light source and incident on the corresponding aspherical lens 23 of the lens array 2 is is refracted to the optical axis a _C side becomes parallel rays constituting the optical axis a _C phrase angle φ proceeds medium aspheric lens 23. Among them, a light beam emitted from the end of the optical fiber 11A in parallel to the z-axis that is the optical axis, that is, the central light beam of the in-lens parallel light enters the lens and then passes through the concave focal point.

As described above, the thickness of the aspheric lens 23 is set just to the concave side focal length f _c, it has become the site and the flat surface on the back surface 24B, since there partial transmission film 4 is subjected , predetermined strength component of the parallel light as described later, but is transmitted through the partial transmission film 4 is emitted at an angle of ψ with respect to the optical axis a _C, the remaining strength component are described above in part permeable membrane 4 The light is reflected at an angle φ and reaches the surface of the aspheric lens 23 again at a position in the x direction symmetrical to the optical axis. The reflected light reaches the surface of the aspheric lens 23 is a parallel light having passed through the concave side focal, emitted from the optical fiber 11A, symmetrical with respect to the non-light path incident on the spherical lens 23 and the optical axis A _C follow a path, it will be focused on the end surface P2 of the optical fiber 11B in the symmetrical position of the optical fiber 11A with respect to the end optical axis a _C.

Here, if parallel light reflected to the thickness of the aspheric lens 23 and thinner than the concave side focal length f _c will become the lens thickness reaches the optical axis A _C-side surface than in the case of f _c, where parallel The light is not converged and spreads more at the end face P2 of the optical fiber 11B. On the other hand, if the lens thickness is thicker than f _c, the reflected light will be reached more outer surface of the aspherical lens 23, the collimated light too is converged, the end face of the optical fiber 11B P2, it may spread Eventually become. In either case, the optical axis of the reflected light is also different from that of the fiber array 1. The optical fiber 11A and 11B the end faces P1, P2 of the distance between the aspheric lens 23 is set to the convex side focal length f _v, it is necessary at the same time the rear surface 24B of the lens array 2 is concave focal plane .

As shown in FIG. 5, the light beam transmitted through the partially transmissive film 4 has a lens refractive index n _c , an angle φ, and a Snell law if the refractive index of the adjacent medium is the same as the refractive index n _v of the air layer 3. Is emitted at an angle ψ according to Although not shown in the figure, if the refractive index of the adjacent medium is the same as the refractive index of the lens array 2, the light is emitted at an angle φ.

  When attempting to realize low-loss coupling between the optical fibers 11A and 11B with such a reflection optical system, the surface shape required for the aspherical lens 23 is a second-order or higher-order rotational curved surface.

A parameter setting example that enables the configuration of the present embodiment will be described. First, the names and symbols of the parameters shown in FIG. 5 are shown in the left column of FIG. In FIG. 5, a light beam emitted from an optical fiber 11A having an end surface on the convex focal plane, passing through the air layer 3 and entering the aspherical lens 23 becomes parallel light having an angle of φ with the optical axis. Accordingly, among these rays, the surface tangent plane of the aspherical lens 23 is exactly parallel to the optical axis for the ray incident on the intersection of the lens optical axis _AC and the lens surface (that is, the convex vertex of the aspherical lens 23). because perpendicular to a z-axis, the incident angle to the center of the aspherical lens 23 of the beam [psi, the outgoing angle φ and the refractive index n _v, Snell law holds between n _c.
(Equation 1)
n _v sinψ = n _c sinφ (1)
However, n _v is the refractive index of the air layer 3, the n _c is the refractive index of the lens array 2.

Further, in the fiber array 1 is fiber spacing d _f, since the lens array 2 is arrayed at the multiple of 2d _f, convex, concave respective focal lengths f _v, f _c is the fiber spacing d _f If values of the lens center incident angle ψ and the emission angle φ are given, they are determined by the following equations (2) and (3).
(Equation 2)
f _v = (d _f cot ψ) / 2 (2)
(Equation 3)
f _c = (d _f cot φ) / 2 (3)

Expressions (1) to (3) do not include an approximation operation, and are strict expressions. A rotating curved surface symmetric with respect to the optical axis that satisfies this relationship is a higher-order curved surface based on a rotating hyperboloid. . From the expressions (2) and (3), the two focal lengths f _v and f _c of the convex concave side of the aspheric lens 23 are determined, that is, the distance between the optical fibers 11A and 11B and the aspheric lens 23 and the aspheric lens 23. The lens thickness is determined.

Next, conditions for realizing such an optical system will be described. While light emitted from the optical fiber 11A is not spread in accordance with the NA of the optical fiber 11A, the beam diameter BD at entering the aspheric lens 23 adjacent As apparent from FIG. 5, at a distance f _v Non Since it is necessary not to reach the spherical lens, the following conditions must be satisfied.
(Equation 4)
BD≈2NAf _v / n _v <d _f (4)

There are also restrictions on the lens surface shape. The lens array 2 is manufactured by a molding method using a mold. At this time, the radius of curvature in the concave shape grinding process is limited, and is usually 150 μm or more. The lens surface shape is aspherical, and its radius of curvature is minimum at the center of the lens, which is the optical axis, and gradually increases with distance from the optical axis. Therefore, the minimum radius of curvature R ₂₂ which is a problem when the mold is manufactured is the minimum at the center of the lens. Therefore, if this is estimated by spherical approximation, the following equation (5) is obtained.
(Equation 5)
_{R 22 ≒ (n c -n v} ) f v / n v (5)

Now, when coming to here, (5) in the resulting spherical approximation radius of curvature R ₂₂ of the lens holding surface 24A and the distance between the fiber array 1 of the spacer 22 thickness t _s to estimate it follows by using ( 6) It can be expressed by the formula.
(Equation 6)
_{t s ≒ f v + R 22} -√ (R 22 2 -d f 2) (6)

Now, _assuming that the spacer 22 is sandwiched between the fiber array 1 and the lens array 2, the thickness ts of the spacer 22 obtained from the equation (6) is obtained. Built into the holding surface 24A.

In the estimated example of FIG. 6, the values below the lens center incident angle ψ in FIG. 5 are calculated by substituting values into these equations (1) to (6). Fiber spacing _{d f} chose refractive index 1.501 of 250μm and 127 [mu] m, a lens refractive index _{n c} is glass high borosilicate based molded lens weather resistance that are often employed in commercial. Next, with respect to the reflection angle φ, in this embodiment, a fiber pair consisting of the optical fiber 11A and the optical fiber 11B is used as the main optical path, and a so-called tap film that reflects 90% or more and transmits several% is used as the partial transmission film 4. Considering application to an optical tap module, an angle of 5 degrees at which polarization dependence does not occur in partially transmitted light was set.

Convex side focal length _{f v} is 947.3μm if the fiber spacing _{d f} of 250μm and 127 [mu] m, although the 481.2Myuemu, beam diameter at this time, the surface of the optical aspheric lens 23 which is emitted from the optical fiber 11A each BD 227.4μm, smaller than a fiber spacing _{d f} becomes 115.5Myuemu, never the optical spans adjacent aspherical lens. Here, as the NA of the optical fibers 11A and 11B, 0.12 which is a value of a single mode optical fiber having a standard mode diameter of 9.0 / 10.0 μm in the 1.3 / 1.55 μm band was selected.

Further, the spherical approximate curvature radii on the surface optical axis of the aspheric lens 23 are 474.6 μm and 241.1 μm, which are sufficiently larger than 150 μm which is the machining limit of the mold, and the mold lens mold for the lens array 2 is used. Processing is possible. The thickness _{t s} of the spacer 22 is 1018.5μm and 517.4Myuemu, sufficiently smaller than the lens thickness _{f c,} in the molding step, the recess processed simultaneously spacer 22 of the lens array 2 can also be processed.

(Second Embodiment)
FIG. 7 shows a configuration example of the fiber array module according to the present embodiment. The fiber array module according to this embodiment includes a lens array 2 in which a plurality of aspherical lenses 23-1 to 23-4 are arranged, and a fiber array 1 in which a plurality of optical fibers 11A and 11B are arranged. Prepare. Fiber array 1 and the lens array 2 has four fibers - shows an example of a lens optical system, are arranged in parallel on a predetermined plane P _C.

Each aspherical lens 23 provided in the lens array 2 includes a fiber-lens optical system as a basic unit. The optical axis A _C is the center axis of each aspherical lens is arranged in parallel in a predetermined plane P _C. The fiber array 1 has two optical fibers 11A and 11B for each aspheric lens 23-1 to 23-4.

  8 and 9 show a configuration example of a lens array with a spacer. The lens array 2 according to the present embodiment includes a plurality of aspherical lenses 23, a lens holding unit 24, and a plurality of spacers 22 for maintaining an appropriate interval. The lens array 2 in FIG. 8 includes two spacers 22-1 and 22-2, and the lens array 2 in FIG. 9 includes four spacers 22-1, 22-2, 22-3, and 22-4. The area of the plurality of spacers 22 is preferably larger than the projected area of each aspheric lens 23 onto the lens holding surface 24.

The lens holding unit 24 holds a plurality of aspheric lenses 23 on a flat lens holding surface 24A. Aspheric lens 23 is held in a flat lens holding surface 24A, the central axis A _C of the aspheric lens 23 are arranged in parallel to the lens holding surface 24A perpendicular predetermined plane P _C. In the example of FIG. 8, an aspheric lens 23 having the x-axis direction as the array direction is formed on a lens holding surface 24A parallel to the xy plane.

The spacer 22 has a convex surface, that is, a top surface 22A at a position where the height from the lens holding surface 24A is higher than the plurality of aspherical lenses 23. Top surface 22A is parallel to the vertical lens holding surface 24A to the optical axis A _C of the aspheric lens 23. The distance between the top surface 22A and the lens apex is set to be the convex focal length fv shown in FIG.

Backside 24B of the lens holding portion 24 is inclined at a predetermined angle equal with respect to a plane perpendicular to the optical axis A _C of the aspheric lens 23. In FIG. 8, it is parallel to the x-axis and has a predetermined angle deg21 with the lens holding surface 24 </ b> A, and is adapted to the connection with the fiber array 1. The predetermined angle deg21 is approximately 8 degrees, for example, not less than 7 ° and not more than 9 °. The predetermined angle is not limited to 8 degrees.

  As in the first embodiment, the plurality of spacers 22 are provided on both sides of the lens holding surface 24A in the x-axis direction, which is the arrangement direction of the plurality of aspheric lenses 23, on the aspheric lenses 23-1 and 23-. 4 so as to be adjacent to 4. Similarly to the first embodiment, the plurality of spacers 22 are located outside the ends of the plurality of aspherical lenses 23 in the y direction orthogonal to the arrangement direction of the plurality of aspherical lenses 23 in the lens holding surface 24A. Is arranged. The spacer 22 is formed integrally with the lens array 2 as in the first embodiment. The manufacturing method of the lens array 2 is the same as that of the first embodiment.

FIG. 10 shows a second fiber-lens optical system according to this embodiment. Hereinafter, the directions will be described following the orthogonal xyz coordinate axes in the drawing. The left end of the figure, in the xz plane, is parallel to the z-axis, the fiber array 1 arranged with the optical fiber 11A and 11B with equal fiber spacing d _f in the x-axis direction is disposed. The fiber array 1 is configured to be held by a housing such as Tempax glass with a plane parallel to the x-axis and forming a predetermined angle with respect to the y-axis as an end surface.

The fiber-lens optical system of the present embodiment is different from the fiber-lens optical system of the first embodiment in that the rear surface 24B side of the lens array 2 is directly attached to the end surface of the fiber array 1, and the lens is held. The surface 24A faces the opposite side. The distance between the intersection line and the vertex of the aspherical lens 23 between the plane and the back surface 24B to make the optical axis A _C of the lens array 2 is set to be the concave side focal length f _c of FIG. 11.

The relative position of the fiber array 1 and the lens array 2, x-axis direction, the center line (this figure the optical fibers to the optical axis A _C of the aspheric lens 23 is adjacent the fiber array 1, the optical fiber 11A and the optical fiber to match 11B centerline of), y-direction, as the plane formed by the array of the lens optical axis a _C coincides with the plane formed by the center line of the fiber array 1, and, z directions , the distance between the end face and the convex vertex of the lens array 2 of the fiber array 1 is set to match the concave side focal length f _c of the aspherical lens 23. On the right side of FIG. 10, the portion having across the air layer 3 intervals of the convex side focal length f _v, a function of reflecting / transmitting perpendicularly to the z axis is the optical axis of the light of a predetermined wavelength in a desired ratio A permeable membrane 4 is provided. In the first embodiment, the partially transmissive film 4 is directly loaded on the back surface 24B side of the lens array 2, but in FIG. 10 which is the second embodiment, glass having the same refractive index as that of the lens array 2 is separately provided. The substrate 42 is loaded. In such a configuration, the path of light emitted from the end face of the optical fiber 11A will be considered by light ray approximation.

Since the end surface P1 of the optical fiber 11A is located on the concave focal plane, the light beam emitted from the end surface P1 of the optical fiber 11A as a point light source and emitted from the corresponding lens surface of the lens array 2 is a lens. is refracted to the optical axis a _C side, the process proceeds to the air layer 3 medium become parallel rays constituting the lens optical axis a _C phrase angle phi. Among them, the light beam emitted from the end of the optical fiber 11 </ b> A in parallel to the z-axis that is the optical axis, that is, the central light beam of the emitted parallel light passes through the convex focal point when it reaches the partial transmission film 4.

And the thickness of the air layer 3 has been set exactly on the convex side focal length f _v, the site has a flat surface, so there partial transmission film 4 is installed, the predetermined intensity of the collimated light fraction Although emitted at an angle of ψ with respect to the partially transmissive membrane 4 the transmission to the lens optical axis a _C, the remaining strength component is reflected by the partial transmission film 4, symmetrical with respect to the lens optical axis a _C x The surface of the aspherical lens 23 is reached again at the directional position. The reflected light that has reached the surface of the aspheric lens 23 is parallel light that has passed through the convex focal point, and the optical path exits from the optical fiber 11A and exits from the surface of the aspheric lens 23 and the lens optical axis _AC . follow symmetrical paths, it will be focused on the position P2 of the end face of the optical fiber 11B in the symmetrical position of the optical fiber 11A with respect to the end lens optical axis a _C.

Here, if parallel light reflected to the thickness of the air layer 3 is thinner than the convex side focal length f _v will become the thickness of the air layer 3 to reach the surface of the lens optical axis A _C side than the case of f _c Therefore, the parallel light is not converged and spreads more on the end face of the optical fiber 11B. On the other hand, if the thickness of the air layer 3 is thicker than f _v, the reflected light will be reached more outer surface of the aspheric lens 23, and the parallel light too is converged on the end face of the optical fiber 11B is spread eventually Will end up. In either case, the optical axis of the reflected light is also different from that of the fiber array 1. Therefore, the end face and the distance between the aspherical lens 23 of the optical fiber 11A and 11B are set to the convex side focal length f _v, it is necessary that the rear surface 24B of the aspherical lens 23 at the same time a concave focal plane .

Note that light transmitted by the partially permeable membrane 4, as shown in FIG. 10, if the refractive index of the glass substrate 42 that is attached partially transmitting film 4 is the same as the refractive index n _c of the lens array 2, FIG. Although not shown in FIG. Further, if the glass substrate 42 to which the partial transmission film 4 is attached is a parallel substrate, when the light is finally emitted to the air layer 3, it is emitted at an angle φ.

  When attempting to realize low-loss coupling between the optical fibers 11A and 11B with such a reflective optical system, the surface shape required for the aspherical lens 23 is a second-order or higher-order rotational curved surface.

  A parameter setting example that enables the configuration of the present embodiment will be described. First, the names and symbols of the parameters shown in FIG. 10 are shown in the left column of FIG. These are the same as those in FIG. 6 described in the first embodiment. However, as the direction of the lens array 2 with respect to the fiber array 1 is reversed, the magnitude relationship between the reflection angle φ and the lens center incident angle ψ is also changed. The big difference is that it is reversed.

In FIG. 10, a light beam emitted from the optical fiber 11A whose end face is directly bonded to the concave focal plane and emitted from the surface of the aspheric lens 23 through the lens array 2 is an angle between the lens optical axis _AC and φ. Becomes parallel light. Therefore, of those rays, for light incident on the intersection of the surface of the z parallel lens optical axis to axis A _C aspheric lens 23, Table interviews plane of the aspheric lens 23 is just the lens optical axis A _C because it is perpendicular to the z-axis is parallel to the central angle of incidence of the aspherical lens 23 of the beam [psi, the outgoing angle φ and the refractive index n _v, Snell law holds between n _c.
(Equation 7)
n _c sinψ = n _v sinφ (7)

Further, in the fiber array 1 is fiber spacing d _f, since the lens array 2 is not being arrayed at the multiple of 2d _f, convex, concave respective focal lengths f _v, f _c is the fiber spacing _If the values of df, lens center incident angle ψ, and emission angle φ are given, they are determined by the following equations (8) and (9).
(Equation 8)
f _v = (d _f cot φ) / 2 (8)
(Equation 9)
f _c = (d _f cot ψ) / 2 (9)

(8) - (9) not within the approximate operation in equation a strict equation, symmetric rotation curved surface in the lens optical axis A _C satisfying this relationship, higher that the spheroid basic It becomes a curved surface. From the expressions (8) and (9), the two focal distances f _v and f _c of the aspherical lens 23 are determined, that is, the distance between the optical fibers 11A and 11B and the aspherical lens 23 and the lens thickness are determined. The conditions for the beam diameter BD on the surface of the aspheric lens 23 are as follows.
(Equation 10)
BD≈2NAf _c / n _c <d _f (10)

The conditions for realizing such an optical system are the same as those in the first embodiment described above. By substituting values into these equations (7) to (10), the values below the lens center incident angle ψ in FIG. 10 were calculated using the equations (5) and (6) described above. 11 estimation examples. Fiber spacing _{d f} chose refractive index 1.501 of 250μm and 127 [mu] m, a lens refractive index _{n c} is glass high borosilicate based molded lens weather resistance that are often employed in commercial. Next, with respect to the reflection angle φ, in this embodiment, an optical tap in which a fiber pair consisting of optical fibers 11A and 11B is a main optical path, and a so-called tap film that reflects 90% and transmits several percent is a partially transmissive film 4. Considering application to the module, an angle of 8 degrees at which polarization dependence does not occur in partially transmitted light was set.

Convex side focal length _{f v} is 889.4μm if the fiber spacing _{d f} of 250μm and 127 [mu] m, although the 451.8Myuemu, beam diameter at this time, the surface of the optical aspheric lens 23 which is emitted from the optical fiber 11A each BD 214.6μm, smaller than a fiber spacing _{d f} becomes 109.0Myuemu, never the optical spans adjacent aspherical lens. Here, as the NA of the optical fibers 11A and 11B, 0.12 which is a value of a single mode optical fiber having a standard mode diameter of 9.0 / 10.0 μm in the 1.3 / 1.55 μm band was selected. Further, the spherical approximate curvature radius on the optical axis of the lens surface is 445.6 μm and 226.4 μm, which is well above the 150 μm which is the machining limit of the mold, and the mold processing of the mold lens for the lens array 2 is possible. . The thickness _{t s} of the spacer 22 is 966.2μm and 490.8Myuemu, sufficiently smaller than the lens thickness _{f c,} in the molding step, the recess processed simultaneously spacer 22 of the lens array 2 can also be processed.

2, 3, 8, and 9, when the number of channels is 4, the length of the lens array 2 in the x direction is approximately 4 mm, and the length in the y direction is approximately 2 mm. . Diameter of the aspherical lens 23, which may be twice the fiber spacing d _f, between the adjacent non-spherical lens 23 may be provided with the flat portion of the 1 [mu] m. Further, the edge of the spacer 22 is curved in accordance with the minimum radius of curvature for mold fabrication, but the minimum radius of curvature for mold fabrication is usually 150 μm, so that it is exaggerated in comparison with the actual appearance in the external view. Yes.

(Third embodiment)
FIG. 12 shows an example of the fiber array module according to this embodiment. The fiber array module shown in FIG. 12 includes the fiber array module shown in FIG. 1, a partially transmissive film 4, a light shielding plate 7 that functions as an optical component, and a lens array 9. The lens array 2 functions as a first lens array, and the lens array 9 functions as a second lens array.

  The partial transmission film 4 forms a reflective surface common to the respective aspheric lenses 23, transmits part of the light that has become parallel light by the individual aspheric lenses 23, and reflects most of the rest. The light shielding plate 7 has a plurality of through holes 71. Each parallel light transmitted from the reflection surface of the partial transmission film 4 enters one end of a different through hole 71. Then, the parallel light after passing through the through holes 71 is emitted from the other end of each through hole 71. The lens array 9 condenses each light emitted from the other end of the plurality of through holes 71 at a point determined for each through hole 71. In this respect, an optical functional element may be installed.

  FIG. 13 shows an example of the light receiving module according to this embodiment. The light receiving module shown in FIG. 13 includes the fiber array module shown in FIG. 12 and the light receiving element array 8. Each light receiving element 81 provided in the light receiving element array 8 receives each light condensed by the lens array 9. The light receiving module shown in FIG. 13 can be used as a four-array optical tap monitor module.

The application area of this embodiment is an optical communication system with a wavelength of 1.55 μm. The module includes a fiber array 1, a lens array 2, a partial transmission film 4, a light shielding plate 7, a lens array 9, and a light receiving element array 8 from the left side of the figure. The various parameters, including fiber spacing d _f, can be realized in reality by using the values shown in FIG. 6 as an example.

  First, the operation and function of the module will be described. 95% of the light rays incident on the lens array 2 from the optical fiber 11A are reflected by the partial reflection film 4 at the reflection angle φ (5 degrees) and enter the optical fiber 11B, and 5% of the incident light intensity is tapped. Return to the main line. The tap light of 5% intensity is an air layer in the subsequent stage and is emitted at an emission angle ψ (7.5 degrees). However, the tap light transmitted through the space is in the subsequent stage of the partial transmission film 4. In order to prevent a decrease in crosstalk due to the mixing between them, a light shielding plate 7 having a through hole 71 is provided. The light shielding plate 7 has a size that is the same as the outer shape of the lens array 2, and a through hole 71 having the beam diameter is formed in the center of the light shielding plate 7 in accordance with the tap optical path. A lens array 9, which is the same as the lens array 2, is installed in the rear stage of the light shielding plate 7 with the direction opposite to that of the lens array 2. The lens array 9 condenses the tap light beam propagating through the space to the light receiving surface of the light receiving element array 8 at the subsequent stage and spread by the diffraction effect on the light receiving surface of the light receiving element 81.

The above components will be described below.
Fiber array 1: The fiber array 1 is a single mode tape fiber in which eight single mode fibers for a wavelength of 1.3 / 1.55 μm band are arrayed at intervals of 250 μm. This was aligned with a 60 mm V-groove plate having a thickness of 1 mm with Tempax glass, covered with a 1 mm thick upper lid, fixed with UV adhesive, and end-face polished to produce a connecting fiber array 1. Fiber distance _{d f} is the same 250μm as tape fiber used. The optical axis of the fiber is the z direction in FIG. 12, and the connection end surface with the lens array 2 is parallel to the x axis, and is inclined by 8 degrees with respect to the y axis direction in order to reduce return light due to end surface reflection. Is set. The angle of the core end face with respect to the optical fiber optical axis is not limited to 8 degrees. The 8 ° oblique end surface has an AR coating for a wavelength of 1.55 μm. The total width in the x-axis direction is 4 mm.

  Lens array 2: The refractive index is made of borosilicate glass having a wavelength of 1.55 μm and a wavelength of 1.501, and the upper surface of a flat glass having a thickness of 1428.8 μm (z direction) is 4000 × 2000 μm (xx). Further, an aspheric lens 23 is formed with an array interval of 500 μm. A 1 μm flat portion is provided between adjacent aspherical lenses 23, and the sag amount, which is a convex amount from the flat portion, is 69 μm.

  Spacers 22 that are integrally molded at the time of lens molding are installed at both ends of the lens array 2 in the x direction, and the surface of the spacer 22 has an angle that matches the 8 ° oblique end surface of the fiber array 1. The area is 1 × 1.5 mm (x × y) on one side. The height of the spacer 22 is preferably set to be a predetermined convex focal length (947.3 μm in this case) at the optical axis position.

Here, the angle of the spacer 22 will be described with reference to FIG. The angle of the normal line L _n of the core end face of the optical fiber 11 with respect to the z axis, which is also the optical axis of the optical fiber 11, is θ ₁ , and the core end face normal of the center light of the light emitted from the core end face of the optical fiber 11 to the air layer 3 If the angle with respect to L _n was theta _2, the angle theta ₁ and the angle theta _2, the Snell's law, satisfies the following relationship.
(Equation 51)
θ ₂ = sin ⁻¹ (sin (θ ₁ ) n _f / n _v ) (51)

Here, n _f is the transmission refractive index of the propagation light of the optical fiber 11. Therefore, when n _f is 1.445, the refractive index n _v of the air layer 3 is 1, and the angle θ ₁ is set to 8 degrees, the angle θ ₂ is 11.6 degrees. The optical coupling between the optical fiber and the lens system has the highest efficiency when the light emitted from the optical fiber 11 is perpendicular to the lens surface. In this case, as is apparent in FIG. 18, the lens-side angle of the flat surface 22B and the fiber array side of the oblique end face 22A of the spacer 22, i.e. the inclination angle of the spacer 22 also becomes equal 11.6 degrees theta _2. In other words, the angle θ _{2 of the} spacer 22 is in addition to the angle θ ₁ (8 degrees) of the end face of the optical fiber 11 and the refraction angle (3.6) from the optical fiber optical axis (z axis) in the air layer 3. The angle is the sum of degrees.

A partial transmission film 4 having an incident angle φ set to 5 degrees is attached to the back surface 24B of the lens array 2. The reflection / transmission ratio is preferably 95% / 5%, and examples of the material include a SiO ₂ —TiO ₂ multilayer film formed by ion beam assisted deposition.

  Light-shielding plate 7: The light-shielding plate 7 is made of a rectangular infrared absorbing glass having an outer shape of 4000 × 2000 × 1000 μm. As shown in FIGS. 12 and 13, the central portion thereof is 300 μm parallel to the xz plane and having an angle of 7.5 degrees, which is the lens axis incident angle ψ, parallel to the xz plane in accordance with the optical path of the tap light. A corner through hole 71 is formed. The x-direction array pitch is 500 μm, which is the same as the lens array 2. When the beam diameter of the tap light is 227.4 μm shown in FIG. 6, the tap light propagates without contacting the wall of the through hole 71 of the light shielding plate 7, but in the lens array 2 or the partial transmission film 4 in the previous stage. The irregular reflection component caused by the structural irregularity caused by reflection and transmission is blocked by the light shielding plate 7, and reaches the light receiving element array 8 to prevent crosstalk.

  Lens array 9: Here, the same lens array 9 as the lens array 2 is used. Usually, since the light receiving surface of the light receiving element 81 is separated from the package surface by about 1 mm, a focal length adjusting resin 91 is inserted between the lens array 9 and the light receiving element array 8 to make the lens array 2 have a longer focal length, The light is collected in the light receiving surface of the light receiving element 81 in the array 8. The directions of the lens array 9 and the lens array 2 are opposite because the focal length adjustment resin 91 fills the space between the lens array 9 and the light receiving element array 8. The lens array 9 was AR coated only on the flat back surface 24B side.

  Light receiving element array 8: The light receiving element 81 is, for example, an InGaAs photodiode array having a light receiving diameter of 80 μm and a 500 μm pitch 4 array. The diode array is sealed, and the distance from the package surface to the diode light receiving part is approximately 1 mm. As can be seen from the side view of FIG. 13, the light receiving element array 8 is connected to the lens array 9 with an inclination from the optical axis which is the z-axis direction.

  As shown in the side views of FIGS. 12 and 13, since the connection interface from the fiber array 1 to the light receiving element array 8 is all kept oblique, it has a structure that prevents reflected return light.

Assembly process: The process has three processes.
The first step is connection between the fiber array 1 and the lens array 2. This is an optical fiber-waveguide connection device, in which alignment light is incident from the optical fibers 11A-1 and 11A-4, which are both ends of the fiber array 1, and the optical fibers 11B-1 and 11B-4. The connection was made in the same process as a normal fiber-waveguide connection in which the biaxial alignment was fixed while monitoring the light from. Here, a significant difference from the conventional connection process is that the alignment in the z-axis direction is not necessary because the position of the optical axis, that is, the z-axis direction is determined by the thickness of the spacer portion 22. In the embodiment described here, there was an effect of shortening the time by 3/4 compared with the prior art. The connection point is between the spacer 22 and the fiber array 1.
The second step is connection of the light shielding plate 7, the lens array 9, and the light receiving element array 8. These connections are placed under the microscope in the order of the light receiving element array 8, the lens array 9, and the light shielding plate 7. Then, it was performed by a method of fixing the adhesive.
In the third step, the alignment light is incident on the optical fiber 11A-1 and the optical fiber 11A-4, and the output of the light receiving element array 8 is monitored, while the lens array 2 with the fiber array 1, the light receiving element array 8, The light shielding plate 7 with the lens array 9 is connected and fixed.

  Characteristics: The characteristics of the manufactured 4ch tap monitor module at a wavelength of 1.55 μm were an insertion loss of 0.4 to 0.5 dB, a return loss of 46 dB or more, and a light receiving sensitivity of 50 to 60 mA / W. Adjacent crosstalk was also 45 dB or more.

  FIG. 19 shows another form of the fiber array module according to this embodiment. The fiber array module shown in FIG. 19 has an AR plate 101 attached to the end face of the fiber array 1, and includes a GRIN lens array 109 instead of the light shielding plate 7 and the lens array 9 shown in FIG. The fiber array module may be the fiber array module according to the first embodiment shown in FIG.

  The AR plate 101 is obtained by attaching an AR film to one side of a transparent thin plate having a refractive index substantially equal to the equivalent refractive index of an optical fiber. When it is difficult to form an AR film directly on the end face of the fiber array 1, a transparent surface having substantially the same refractive index as that of the end face of the fiber array 1 is formed on the end face of the AR plate 101 where the AR film is not formed. It is used by attaching with an adhesive to obtain the same effect as the direct AR coating.

  FIG. 20 shows another embodiment of the light receiving module according to this embodiment. The light receiving module shown in FIG. 20 includes the fiber array module shown in FIG. 19 and the light receiving element array 8. Each light receiving element 81 provided in the light receiving element array 8 receives each light condensed by the GRIN lens array 109.

  The GRIN lens array 109 includes a plurality of GI (Graded Index) fibers 174-1 to 174-4 that function as GRIN lenses. The GRIN lens array 109 has a size that is the same as the outer shape of the lens array 2, and GI fibers 174-1 to 174-4 are arranged in the center of the GRIN lens array 109 according to the tap optical path. The GI fibers 174-1 to 174-4 are preferably fixed by being sandwiched between two V-groove plates. Each parallel light transmitted from the partial transmission film 41 enters one end of different GI fibers 174-1 to 174-4. And each light radiate | emitted from the other end of GI fiber 174-1 to 174-4 is condensed on the points P9-1 to 9-4 defined for every GI fiber 174-1 to 174-4. At this point, the light receiving surface of the light receiving element 81 is disposed.

The length and refractive index distribution of the GI fibers 174-1 to 174-4 are arbitrary. For example, as shown in FIGS. 19 and 20, when the light receiving element 81 is arranged at an equal distance from the partial transmission film 4, GI fibers 174-1 to 174-4 having the same refractive index distribution and the same length are used. Further, depending on the length of the GI fibers 174-1 to 174-4, the thicker the lens, the closer the focal point is, and the thinner the lens thickness, the far the focal point. Therefore, by changing the length of the GI fibers 174-1 to 174-4 as shown in FIG. 21, the distance from the partially transmissive film 4 to the points P9-1 to 9-4 is changed, and the array of light receiving elements 81 The interval d _p can be adjusted. Note that the refractive index distribution of the GI fibers 174-1 to 174-4 may be changed instead of or in combination with the length of the GI fibers 174-1 to 174-4.

(Fourth embodiment)
FIG. 14 shows an example of the fiber array module according to the present embodiment. The fiber array module shown in FIG. 14 includes the fiber array module shown in FIG. 7, a light shielding plate 7, and a lens array 9. The lens array 2 functions as a first lens array, and the lens array 9 functions as a second lens array.

  The partial transmission film 4 forms a reflective surface common to the respective aspheric lenses 23, transmits part of the light that has become parallel light by the individual aspheric lenses 23, and reflects most of the rest. The light shielding plate 7 has a plurality of through holes 71. Each parallel light transmitted from the reflection surface of the partial transmission film 4 enters one end of a different through hole 71. Then, the parallel light after passing through the through holes 71 is emitted from the other end of each through hole 71. The lens array 9 condenses each light emitted from the other end of the plurality of through holes 71 at a point determined for each through hole 71. At this point, the light receiving surface of the light receiving element 81 is arranged.

  FIG. 15 shows an example of a light receiving module according to this embodiment. The light receiving module shown in FIG. 15 includes the fiber array module shown in FIG. 14 and the light receiving element array 8. Each light receiving element 81 provided in the light receiving element array 8 receives each light condensed by the lens array 9. The light receiving module shown in FIG. 15 can be used as a four-array optical tap monitor module.

The application area is an optical communication system with a wavelength of 1.55 μm. The module includes a fiber array 1, a lens array 2, a partially transmissive film 4, a light shielding plate 7 that functions as an optical component, a lens array 9, and a light receiving element array 8 from the left side of the figure. The various parameters, including fiber spacing d _f, can be realized in reality by using the values shown in FIG. 11 as an example.

  First, the operation and function of the module will be described. 95% of the light rays that directly enter from the back surface 24B of the lens array 2 and exit from the surface of the aspherical lens 23 without passing through the air layer from the optical fiber 11A are reflected by the partially transmissive film 4 at a reflection angle φ (8 degrees). The reflected light returns to the lens array 2 again and enters the optical fiber 11B, and 5% of the incident light intensity is tapped to return to the main line. The tap light having 5% intensity passes through the glass substrate 42 parallel to the partial transmission film 4 to the air layer 3 and is emitted at an emission angle φ (8 degrees). In the subsequent stage, a light shielding plate 7 having a through hole 71 is provided in order to prevent a decrease in crosstalk due to mixing of tap lights transmitted through the space. The light shielding plate 7 has a size that is the same as the outer shape of the lens array 2, and a 300 μm square through hole 71 is formed in the center of the light shielding plate 7 according to the tap optical path. A lens array 9, which is the same as the lens array 2, is installed behind the light shielding plate 7 with the same orientation as the lens array 2. The lens array 9 condenses the tap light beam that has propagated through the space and spread by the diffraction effect on the light receiving surface of the light receiving element 81.

In the following, the components that do not overlap with those of the third embodiment will be described.
Fiber array 1: Unlike the third embodiment, the AR coating is not applied to the surface of the end face which is inclined 8 degrees. Note that the angle of the core end face with respect to the optical fiber optical axis is not limited to 8 degrees, as in the third embodiment.

  Lens array 2: The refractive index is made of borosilicate glass having a wavelength of 1.55 μm and a wavelength of 1.501, and the aspherical lens 23 is z at the center portion on the lens holding surface 24A parallel to the xy plane with an array interval of 500 μm. It is formed facing the positive direction of the shaft. A 1 μm flat portion is provided between adjacent aspherical lenses 23, and the sag amount, which is a convex amount from the flat portion, is 75 μm. Spacers 22 that are integrally formed at the time of lens molding are installed at both ends of the lens array 2 in the x direction. The surface of the spacer 22 is parallel to the lens holding surface 24A, and its area is 1 × 1.5 mm (x × y) on one side. The height is set to be a predetermined convex focal length (here 889.4 μm) at the optical axis position.

Backside 24B of the lens array 2 is parallel to the end face of the fiber array 1, has a diagonal relative to the y-axis, z-direction distance is concave focal length f _c from the lens convex surface vertex to the diagonal backside 24B It is set to become.

Partially permeable film 4 and glass substrate 42: In this embodiment, the partially permeable film 4 is attached to the glass substrate 42. Glass substrate 42, and the lens array 2 is intended to have a have and the same refractive index n _c a separate transparent substrate. A partially transmissive film 4 having an incident angle φ set to 8 degrees is attached on the glass substrate 42 whose both surfaces are parallel. The reflection / transmission ratio is preferably 95% / 5%, and examples of the material include a SiO ₂ —TiO ₂ multilayer film formed by ion beam assisted deposition.

  Light-shielding plate 7: The light-shielding plate 7 is made of a rectangular infrared absorbing glass having an outer shape of 4000 × 2000 × 1000 μm. As shown in FIGS. 14 and 15, a 300 μm square through-hole is formed in the central portion, which is parallel to the xz plane and forms an angle of 8 degrees with the z-axis direction and the reflection angle φ in accordance with the optical path of the tap light. Has been opened. The x-direction array pitch is 500 μm, which is the same as the lens array 2. When the beam diameter of the tap light is 214.6 μm shown in FIG. 11, the tap light propagates without contacting the wall of the through hole 71 of the light shielding plate 7, but in the lens array 2 or the partial transmission film 4 in the previous stage. The irregular reflection component caused by the structural irregularity caused by reflection and transmission is blocked by the light shielding plate 7, and reaches the light receiving element array 8 to prevent crosstalk.

  As shown in the side views of FIGS. 14 and 15, since the connection interface from the fiber array 1 to the light receiving element array 8 is all kept oblique, it has a structure that prevents reflected return light.

  Assembly process: The difference from the third embodiment is that the lens array 2 and the partial transmission film 4 are first connected in the first process. This is because the partially permeable membrane 4 is a simple flat plate, and therefore alignment work is not necessary, and connection can be made only by mold matching work. Others are the same as in the third embodiment.

  Characteristics: The characteristics of the manufactured 4ch tap monitor module at a wavelength of 1.55 μm were an insertion loss of 0.4 to 0.5 dB, a return loss of 46 dB or more, and a light receiving sensitivity of 50 to 60 mA / W. Adjacent crosstalk was also 45 dB or more. The characteristics were the same as in the third embodiment.

(Fifth embodiment)
In the above-described embodiment, the array is a one-dimensional array, but a two-dimensional array is also possible. In that case, the fiber array modules shown in FIG. 1 or FIG. 7 are arranged in parallel in the y direction.

  In this case, the most serious problem is the fiber array 1. The connection surface seen from the z direction is shown in FIG. The optical fiber array 1 shown in FIG. 16 includes V-groove plates 13-2 to 13-5 having a 60-degree V-groove 14 for the fiber array. The V-groove plates 13-2 to 13-5 are provided with alignment V-grooves 15-1 and 15-2 on both sides of the V-groove 14 array. Further, alignment grooves 15-3 and 15-4 are formed on the back surfaces of the V-groove plates 13-2 to 13-5 at the same position in the x direction as the front surface side. The alignment optical fiber 12 may be the same as the optical fibers 11A and 11B shown in the figure.

In this case, if the opening width of the V-groove 14 is W ₁₄ and the opening width W ₁₅ of the alignment grooves 15-1, 15-2, 15-3, and 15-4 is,
W ₁₄ = 2 (R _f √3-d ₁₃ / √3) (11)
(Equation 12)
W ₁₅ = (2R _f −d ₁₃ ) / √3 (12)
Should be set. Then, when the alignment optical fiber 12 is just fitted into the alignment groove 15, the waveguide optical fiber 11 is pressed by the upper plate by the upper plate. Here, _{R f} is the radius of the optical _{fiber, d 13} is the distance of the upper and V-shaped groove plate 13-2～13-5. In this _embodiment, the since the _{d 13} and 20 [mu] m _W 14 = 193 _nm, and w 15 = 61 [mu] m.

  The alignment grooves 15-1, 15-2, 15-3, and 15-4 need to have the same position in the x direction on the front and back of the V-groove plate 13. In such a groove processing apparatus, the perpendicularity of the upper and lower focusing axes of the groove forming position observation lens barrel to the processing surface may be adjusted in advance. Thus, the 8 × 4 fiber array made of Tempax glass has an x-direction pitch of 250 μm and a y-direction pitch of 1 mm. As a result, a 4 × 4 array fiber array module and a light receiving module having a pitch of 500 μm in the x direction and a pitch of 1 mm in the y direction can be manufactured.

  Here, as shown in the side view of FIG. 17, the fiber array 1 is preferably subjected to partial oblique processing only in the vicinity of the core of the optical fiber. This is because, if the entire surface of the end face of the array is inclined, it is extremely difficult to make all the components after the lens array 2 and subsequent stages into a two-dimensional array. A dual head dicing saw can be used for processing. This is a device equipped with two dicing heads in a column and can be continuously processed using two different blades in one process.

  The lens arrays 2 and 9 other than the fiber array 1, the light shielding plate 7, and the light receiving element array 8 are also made into a 2D array, and all are 4 × 4 arrays with a pitch of 500 μm in the x direction and a pitch of 1 mm in the y direction. A side view of the manufactured 4 × 4 tap monitor module is shown in FIG. As for the appearance, the top view is exactly the same as FIG. 12, and the side view has a form of being stacked in the y direction.

(Effects of the present disclosure)
As described above, the lens array 2 of the present disclosure and the module using the same have the following advantages.
Since the spacer 22 is formed integrally with the lens array 2, a process for separately manufacturing the spacer 22 and a process for attaching the spacer 22 to the lens array 2 are not required, thereby reducing the cost due to the number of processes. it can.
Since the spacer 22 is formed integrally with the lens array 2, mass production of the lens array 2 is facilitated by producing the lens array 2 by a glass mold using a mold that has been well adjusted in advance. , Can stabilize the quality.
Since the protruding amount of the spacer 22 is larger than that of the aspheric lens 23, the aspheric lens 23 can be prevented from being scratched.
By adjusting the protruding amount of the spacer 22 in accordance with the alignment in the optical axis direction, alignment in the optical axis direction in the connection process between the fiber array 1 and the lens array 2 can be omitted. For this reason, it is possible to shorten the time for the connection process between the fiber array 1 and the lens array 2 and to prevent the fiber array 1 or the lens array 2 from being damaged during alignment.
-Overall, the number of defective products is reduced, the amount of waste discharged is small, and the environmental impact is low.

  The present disclosure can be applied to the information communication industry.

1: Fiber array 11, 11A, 11A-1, 11A-2, 11A-3, 11A-4, 11A-11, 11A-12, 11A-13, 11A-14, 11A-21, 11A-31, 11A- 41, 11B, 11B-1, 11B-2, 11B-3, 11B-4, 11B-11, 11B-12, 11B-13, 11B-14, 11B-21, 11B-31, 11B-41: optical fiber 12-1, 12-2: Positioning optical fibers 13-1, 13-2, 13-3, 13-4, 13-5: V groove plate 14: V grooves 15-1, 15-2, 15- 3, 15-4: Alignment grooves 2, 9: Lens array 22: Spacer portion 23: Aspherical lens 24: Lens holding portion 24A: Lens holding surface 24B: Back surface 3: Air layer 4: Partial transmission film 42: Glass substrate 53: Upper mold 54: Lower Type 55: raw glass gob 7: shielding plate 71: through hole 8: photodiode array 91 is a focal length adjusting resin 101: AR plate 109: GRIN lens array 174: GI fiber

Claims (10)

A plurality of aspheric lenses that are held by a flat holding surface and in which a central axis of the lens is arranged in parallel in a predetermined plane perpendicular to the holding surface;
A lens holding unit for holding the plurality of aspheric lenses on the flat holding surface;
A plurality of convex portions arranged on the holding surface and having convex surfaces at positions higher than the plurality of aspheric lenses from the holding surface;
With
Each convex surface provided in the plurality of convex portions is inclined at a predetermined angle equal to a surface perpendicular to the optical axis of the aspheric lens,
Lens array. A plurality of aspheric lenses that are held by a flat holding surface and in which a central axis of the lens is arranged in parallel in a predetermined plane perpendicular to the holding surface;
A lens holding unit for holding the plurality of aspheric lenses on the flat holding surface;
A plurality of convex portions arranged on the holding surface and having convex surfaces at positions higher than the plurality of aspheric lenses from the holding surface;
With
Each convex surface provided in the plurality of convex portions is parallel to a surface perpendicular to the optical axis of the aspheric lens,
The back surface of the holding portion facing the convex surface is inclined at a predetermined angle equal to the surface perpendicular to the optical axis of the aspheric lens;
Lens array. The plurality of convex portions are outside of both ends of the plurality of aspheric lenses in the arrangement direction of the plurality of aspheric lenses in the holding surface and orthogonal to the arrangement direction of the plurality of aspheric lenses. Is disposed outside both ends of the plurality of aspheric lenses in the direction of
The lens array according to claim 1 or 2. The area of the plurality of convex surfaces is wider than the projected area of the aspheric lens on the holding surface,
The plurality of convex portions are disposed at positions adjacent to both ends of the plurality of aspheric lenses in the arrangement direction of the plurality of aspheric lenses, in the holding surface.
The lens array according to claim 1. Each of the two optical fibers has one aspheric lens, and each of the aspheric lenses condenses light from the two optical fibers on one point of a reflection surface defined for each of the aspheric lenses. The first lens array according to any one of claims 1 to 4,
Each of the aspheric lenses included in the first lens array has two optical fibers, and the longitudinal direction of each optical fiber is arranged in parallel to the central axis of the aspheric lens within the predetermined plane. Fiber array
A fiber array module comprising: The angle of the end face of the optical fiber with respect to a plane perpendicular to the optical axis of the optical fiber in the first lens array is approximately 8 degrees,
The predetermined angle in the first lens array is determined according to an angle of an end face of the optical fiber and a refraction angle of outgoing light of the optical fiber.
The fiber array module according to claim 5. Forming a reflecting surface of each of the aspherical lenses, transmitting a part of the light condensed at the one point, and reflecting a part of the light condensed at the one point;
Each of the GRIN lenses has a plurality of GRIN lenses, and each of the parallel lights transmitted from the reflecting surface is incident on one end of the different GRIN lens, and each light emitted from the other end of the GRIN lens is determined for each GRIN lens. A GRIN lens array that collects light at a point,
Further comprising
The fiber array module according to claim 5 or 6. A fiber array module according to claim 7,
A light receiving element array for receiving each light condensed by the GRIN lens array;
A light receiving module comprising: Forming a reflecting surface of each of the aspherical lenses, transmitting a part of the light condensed at the one point, and reflecting a part of the light condensed at the one point;
Light having a plurality of through holes that transmit the light transmitted from the partial transmission film, and each light transmitted from the partial transmission film is incident on one end of the different through holes, and the light after passing through the through holes An optical component that emits from the other end of each through-hole,
A second lens array for condensing each light emitted from the other end of the plurality of through holes at a point determined for each through hole;
Further comprising
The fiber array module according to claim 5 or 6. The fiber array module according to claim 9,
A light receiving element array for receiving each light condensed by the second lens array;
A light receiving module comprising:

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