JP2006146072A - Ball lens fixing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a ball lens fixing structure that enables an optical fiber and a ball lens to be aligned more easily and more accurately. <P>SOLUTION: With a groove 3b formed on the surface 3a of a substrate 3, a spring 9 is installed on each of a pair of oppositely facing side walls 4c of the groove 3b while a through hole 14 is formed on the bottom wall 4d of the groove 3b. In the through hole 14, a supporting pin 15 is inserted projectingly into the groove 3b, with a ball lens 6 held horizontally between the springs 9 as well as vertically by the supporting pin 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ball lens fixing structure used in an input / output unit or the like of an optical device used in an optical communication field or the like.

  Various optical devices have been put into practical use in optical fiber networks that have been expanding in recent years. A ball lens may be used for the input / output unit of these optical devices. In this case, it is important to accurately align (align) the optical fiber and the ball lens. This is because the loss value increases when misalignment occurs. As an example, when the ball lens has a diameter of 400 μm and a refractive index of 1.48 (material: glass), if the misalignment is 2.8 μm, the loss is deteriorated by 2 dB. Here, since the dimensional accuracy of a commercially available general ball lens is 3 μm to 10 μm, an increase in loss value due to misalignment is inevitable if such a ball lens is randomly attached.

  Therefore, conventionally, a method (so-called active alignment method) in which a positional relationship where the loss is minimized while actually passing light is searched for and fixed at that position has been adopted. In most cases, this method is also applied to a fiber with a lens in which a ball lens is attached to the tip of the optical fiber. However, the active alignment method has a problem in that it takes time to perform the alignment work and causes an increase in manufacturing cost.

For this reason, there is a case in which a structure in which a fixed position is determined in advance and a ball lens is installed at a predetermined position without performing the alignment operation as described above (so-called passive alignment method) may be employed (for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-253523

  However, in the passive alignment method, it is often difficult to improve the accuracy of the position and shape of the structure that determines the fixed position. In the case of Patent Document 1, it is difficult to form a fitting cavity with high positional accuracy at the tip of the optical fiber, and it may be difficult to reduce loss.

  Therefore, an object of the present invention is to obtain a ball lens fixing structure that can perform alignment of an optical fiber and a ball lens more easily and with higher accuracy.

  In the ball lens fixing structure according to the first aspect of the present invention, a groove is formed on the surface of the substrate, and a pair of springs arranged symmetrically with respect to the central axis of the groove are provided. A through hole is formed in the through hole, and a support pin is inserted into the through hole so as to protrude into the groove, and the ball lens is horizontally held by the spring structure, and the ball lens is vertically moved by the support pin. It is characterized by supporting in the direction.

  The ball lens fixing structure according to the invention of claim 2 is characterized in that a recess is formed at the upper end of the support pin.

  The optical fiber with a lens according to the invention of claim 3 is characterized in that a ball lens and an optical fiber are attached to the ball lens fixing structure.

  According to the first aspect of the present invention, in the ball lens fixing structure in which a groove is formed on the substrate surface, the ball lens is horizontally held by the spring structure, and the ball lens is supported vertically by the support pin. Therefore, the ball lens can be aligned with the optical fiber more accurately and easily.

  According to the second aspect of the present invention, since the concave portion is formed at the upper end of the support pin, the ball lens can be reliably supported on the support pin.

  According to the invention of claim 3, by performing the alignment using the ball lens fixing structure, it is possible to obtain an optical fiber with a lens that is aligned more easily and at a lower cost with higher accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (First Embodiment) FIG. 1 is a plan view of a substrate constituting a ball lens fixing structure according to this embodiment, and FIG. 2 is a cross-sectional view of the ball lens fixing structure (perpendicular to the substrate surface along the extending direction of the groove). It is sectional drawing in a cross section; AA sectional drawing of FIG. In this specification, for convenience, the stacking direction of the substrates (the vertical direction in FIG. 2) is defined as the vertical direction.

  In the present embodiment, the ball lens fixing structure 1 is configured by forming grooves 3b, 3c and the like on the surface 3a side of the substrate.

  As shown in FIG. 1, the surface 3a of the substrate 3 is formed with a groove 3b having a rectangular shape in plan view and a groove 3c having a rectangular shape in plan view narrower than the groove.

  The groove 3b has a rectangular cross section having a constant size from the opening 4a provided on one end side of the substrate 3 to the end face 4b (having a depth of 1/2 or more of the width, and the depth of at least the ball lens 6 It is formed so as to have a cross section having a diameter variation upper limit value or more.

  A spring 9 having the same shape is formed on each of the pair of side walls 4c of the groove 3b. In this embodiment, the spring 9 is formed in the shape of a cantilever having a rectangular shape in plan view with the opening 4a side (left side in FIG. 1) fixed. The spring 9 can be formed by a known semiconductor process. For example, the back side of the spring 9 (the side opposite to the central axis 8 with respect to the spring 9 in FIG. 1), the side surface (the side opposite to the central axis 8 with respect to the spring 9 in FIG. 3), and the front end side (FIG. 1). An oxide film layer is formed on a portion 10 which is the right side of the spring 9), and the oxide film layer in this portion is eliminated by a so-called wet etching method using a liquid etchant. Can be obtained.

  The pair of springs 9 are formed symmetrically with respect to the central axis 8 of the groove 3b (or a plane perpendicular to the surface 3a including the central axis 8). By forming using a semiconductor process capable of high-precision microfabrication, it is possible to accurately form the desired position and shape.

  In order to allow the pair of springs 9 to hold the ball lens 6 in the left-right direction, the distance between the contact surfaces of the springs 9 is based on the lower limit value (diameter) of the individual difference in the diameter of the ball lens 6. It is set slightly narrower.

  A through-hole 14 into which the support pin 15 is inserted is formed in the bottom wall 4d of the groove 3b. The through hole 14 extends in the vertical direction (that is, the direction perpendicular to the surface of the substrate 3). The support pin 15 can be fixed to a predetermined position in the through-hole 14 by, for example, press-fitting or bonding, and a mortar-shaped recess 15a is formed at the upper end thereof. Therefore, the lower end of the ball lens 6 inserted into the groove 3 b can be supported by the recess 15 a of the support pin 15 fixed to the through hole 14.

  The groove 3c formed so as to be connected to the groove 3b connects the communication part 5a provided on the end surface 4b of the groove 3b and the opening part 5b provided on the end part side of the substrate 3 on the other side of the opening part 4a. Is formed to have a constant rectangular cross section (however, a cross section smaller than the groove 3b). The center position (plane) in the width direction of the groove 3c is set to be the same as the center position (plane) in the width direction of the groove 3b.

  Here, the groove 3c is used as an insertion portion of an optical fiber. The width of the groove 3c is the same as the diameter of the optical fiber so that the center position (plane) in the width direction of the optical fiber coincides with the center position (plane) in the width direction of the groove 3c.

  On the other hand, the groove 3 b is used as an insertion portion for the ball lens 6. The ball lens 6 is held in the left-right direction by a pair of springs 9 in the groove 3b. Here, the pair of springs 9 are formed symmetrically about the central axis 8 and have the same spring constant. Therefore, the center of the ball lens 6 held between the pair of springs 9 is located in a plane extending vertically through the central axis 8 regardless of the size.

  The ball lens 6 is supported in the vertical direction by the support pins 15 in the same groove 3b. Therefore, it is possible to easily arrange the center of the ball lens 6 on the central axis 8 by adjusting the position of the support pin 15 up and down by active alignment or passive alignment.

  Therefore, the center of the ball lens 6 inserted into the groove 3b can be easily aligned with the center axis (and the center of the tip of the optical fiber) 8 of the optical fiber disposed in the groove 3c. That is, by using the ball lens fixing structure 1 according to the present embodiment, a structure in which the ball lens 6 and the optical fiber are accurately aligned can be obtained very easily. The central axis 8 of the grooves 3b and 3c corresponds to the central axis of the optical fiber, that is, the optical central axis.

  Thus, the ball lens fixing structure 1 in which the optical fiber and the ball lens 6 are mounted can be used as an optical fiber with a lens.

  By the way, the grooves 3b and 3c formed on the surface 3a of the substrate 3 can be formed by using a dry etching method. The dry etching method has higher anisotropy than the wet etching method, and is suitable for accurately forming a rectangular groove having a predetermined width on the surface of the substrate 3.

  According to the above embodiment, in the ball lens fixing structure 1 in which the groove 3 b is formed on the surface 3 a of the substrate 3, the ball lens 6 is held in the horizontal direction by the pair of springs 9, and the support pin 15 Since the ball lens 6 is supported in the vertical direction, the ball lens 6 can be aligned with the optical fiber more accurately and easily.

  Further, according to the present embodiment, since the concave portion 15 a is formed at the upper end of the support pin 15, the ball lens 6 can be reliably supported on the support pin 15.

  In addition, according to the present embodiment, by performing alignment using the ball lens fixing structure 1, it is possible to obtain an optical fiber with a lens that is aligned more easily and at a lower cost with higher accuracy.

  (Second Embodiment) FIG. 3 is a plan view of a ball lens fixing structure in which an optical fiber and a ball lens are mounted at predetermined mounting positions. In addition, in this embodiment, it has the component similar to the ball-lens fixing structure concerning the said 1st Embodiment. Therefore, the same reference numerals are assigned to them, and redundant description is omitted.

  The ball lens fixing structure 1 according to the first embodiment has the grooves 3c formed on both sides of the groove 3b on the surface 3a of the substrate 3, whereas the ball lens fixing structure 1A according to the present embodiment In the surface 3a of 3A, the groove 3c is formed only on one side of the groove 3b. However, the configuration of the grooves 3b and 3c itself is exactly the same as in the first embodiment. By attaching the ball lens 6 and the optical fiber 7 to the ball lens fixing structure 1A, it can be used as the optical fiber 20 with a lens.

  That is, according to the present embodiment, by performing alignment using the ball lens fixing structure 1A, it is possible to obtain an optical fiber with a lens that is aligned more easily and cheaply with higher accuracy.

  (Third Embodiment) FIG. 4 is a plan view of a ball lens fixing structure according to this embodiment. The present embodiment also has the same components as the ball lens fixing structure according to each of the above embodiments. Therefore, the same reference numerals are assigned to them, and redundant description is omitted.

  In this embodiment, a plurality of ball lens fixing structures 1A (that is, grooves 3b and 3c, through-holes 14, and support pins 15, and springs 9) according to the second embodiment are arranged in parallel on the substrate 3B. is there. Then, the ball lens 6 and the optical fiber 7 are fixed to each of the plurality of formed grooves 3b and 3c, thereby constructing an aligned optical fiber array 20A with a lens.

  According to this embodiment, an optical fiber array with a lens in which the ball lens 6 and the optical fiber 7 are accurately aligned can be easily obtained without requiring alignment work. As a result, the input / output portions of the optical device can be formed at once, which is advantageous in terms of cost compared to the case where they are separately formed and combined.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made to the above-described embodiments without departing from the gist. For example, it is possible to form a device using this ball lens fixing structure in the same substrate. In this case, there is an advantage that it is not necessary to perform alignment work between the device and the ball lens fixing structure. Moreover, when it is set as the structure which an optical fiber and a ball lens contact, you may make it form an antireflection film in the connection surface. In the above-described embodiment, the method of removing the oxide film layer by the wet etching method has been exemplified. However, it goes without saying that the dry etching method may be used for possible portions.

1 is a plan view of a ball lens fixing structure according to a first embodiment of the present invention. Sectional drawing (AA sectional drawing of FIG. 1) of the ball lens fixing structure concerning 1st embodiment of this invention. The top view of the ball lens fixing structure (optical fiber with a lens) concerning 2nd embodiment of this invention which attached the optical fiber and the ball lens to the predetermined attachment position. The top view of the ball lens fixing structure (optical fiber with a lens) concerning 3rd embodiment of this invention which attached the optical fiber and the ball lens to the predetermined attachment position.

Explanation of symbols

1, 1A Ball lens fixing structure 3, 3A, 3B Substrate 3a Surface 3b Groove 4c Side wall 4d Bottom wall 6 Ball lens 7 Optical fiber 8 Central axis (optical central axis)
9 Spring (spring structure)
14 Through-hole 15 Support pin 20, 20A Optical fiber with lens (array)

Claims (3)

A groove is formed on the surface of the substrate, and a pair of springs arranged symmetrically with respect to the central axis of the groove is provided, while a through hole is formed in the bottom wall of the groove, Insert the support pin so that it protrudes into the
A ball lens fixing structure characterized in that the ball lens is held in the horizontal direction by the spring structure, and the ball lens is supported in the vertical direction by the support pin.   The ball lens fixing structure according to claim 1, wherein a concave portion is formed at an upper end of the support pin. An optical fiber with a lens formed by mounting a ball lens and an optical fiber on the ball lens fixing structure according to claim 1 or 2.

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