Abstract:
An arrayed optical fiber connector for positioning multiple optical fibers to align the end faces of the optical fibers with multiple optical axes at a given input/output face of light is constructed as a board that includes a groove in which the multiple optical fibers are disposed in a given alignment arrangement; a fixing member that is received in the groove and is laid with the multiple optical fibers in a given alignment arrangement; and a fixing plate that is fixed on the surface of the board in which the groove is formed and fixes the multiple optical fibers and the fixing members inside the groove while securing the given alignment arrangement of the multiple optical fibers and the fixing members.

Description:
FIELD OF THE INVENTION 
     This invention relates to a arrayed optical fiber connector that is used to fix multiple optical fibers in alignment and to optically connect with an optical waveguide element with multiple input/output ports. 
     BACKGROUND OF THE INVENTION 
     Along with the practical application of optical communication system in recent years, the system with large capacity, multiple functions and high speed has been required. For example, to generate optical signal with higher speed, to demultiplex/multiplex optical wavelengths in a same optical transmission line, and to add a new function such as switching/exchanging of optical transmission line are required. 
     Of them, especially optical waveguide elements, such as AWG (arrayed waveguide grating) that enables the demultiplexing/multiplexing of optical wavelengths, and a matrix switch that enables the switching of optical transmission line, have been actively developed. The input/output part of these optical waveguide elements are structured such that multiple optical waveguides are arranged at equal intervals, and, to facilitate the optical connection with optical transmission line such as an optical fiber, it employs a arrayed optical fiber connector. 
     FIG. 1 is a perspective view showing a conventional arrayed optical fiber connector. The arrayed optical fiber connector  10  is structured such that multiple (four, in this example) optical fibers  11   a ,  11   b ,  11   c  and  11   d , each of which having a core  1  and a clad  2 , are disposed in an alignment assembly  12 . 
     The alignment assembly  12  is composed of a nearly rectangular-solid-shaped board  13  and a fixing plate  14  that has the same form as the board  13  except having a thickness less than the board  13 . 
     The board  13  is provided with a rectangular-cross-sectional groove  13   a  that contains the optical fibers in alignment at its bottom. The groove  13   a  has a length that extends through between two sides orthogonal to its bottom, a depth that is nearly equal to the diameter of the optical fibers  11   a  to  11   d , and a width that is equal to the sum of the diameters of the optical fibers  11   a  to  11   d.    
     The method of assembling the arrayed optical fiber connector  10  thus composed is explained. First, the tips of the four optical fibers  11   a  to  11   d  are, side by side, inserted into the groove  13   a  provided on the board  13 , and adhesive  15  is filled into the clearance between the groove  13   a  and the optical fibers  11   a  to  11   d . Then, the fixing plate  14  is disposed on the surface where the groove  13   a  is formed of the board  13 , brought in contact with the optical fibers  11   a  to  11   d.    
     Then, by heating the board  13  to harden adhesive  15  while pressing the fixing plate  14 , the board  13 , the optical fibers  11   a  to  11   d  and the fixing plate  14  are integrally fixed, thereby obtaining the arrayed optical fiber connector  10 . 
     The basic performance required to the arrayed optical fiber connector  10  is that the optical fibers  11   a  to  11   d  do not incur the positional deviation when the end face of the arrayed optical fiber connector  10  is polished and after it is connected with an optical waveguide element. If the optical fibers  11   a  to  11   d  incur the positional deviation, there occurs a deterioration in performance such as an increase in connection loss with optical wavelength element that causes a reduction in reliability of optical wavelength element. 
     However, in the conventional arrayed optical fiber connector  10 , there is a problem that it is difficult to prevent the optical fibers  11   a  to  11   d  from incurring the positional deviation when the end face of the arrayed optical fiber connector  10  is polished and after it is connected with an optical waveguide element. 
     FIG. 2 is a plan view illustrating the problem of the conventional arrayed optical fiber connector. 
     As shown, due to the low precision in processing the groove  13   a , the board  13  used for the arrayed optical fiber connector  10  has been manufactured such that the bottom of the groove  13   a  is declined comparing with the upper surface of the board  13 . In this case, even when, like the above method, the optical fibers  11   a  to  11   d  and the fixing plate  14  are integrally fixed while using the board  13  thus manufactured, the fixing plate  14  does not contact all the optical fibers  11   a  to  11   d  since the bottom of the groove  13   a  is declined. As a result, clearances da, db, dc and dd must occur between the fixing plate  14  and the optical fibers  11   a  to  11   d.    
     Thus, the fixing force between the fixing plate  14  and the optical fibers  11   a  to  11   d  is reduced, and the optical fibers  11   a  to  11   d  each are likely to incur the positional deviation according to the clearances da, db, dc and dd when the end face of the arrayed optical fiber connector  10  is polished and after it is connected with an optical waveguide element. Because of this, it is difficult to perfectly prevent the positional deviation. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a arrayed optical fiber connector that the positional deviation of optical fiber can be easily prevented. 
     According to the invention, a arrayed optical fiber connector for positioning multiple optical fibers to align the end faces of the optical fibers to multiple optical axes at a given input/output face of light, comprises: 
     a board that includes a groove in which the multiple optical fibers are disposed in a given alignment state; 
     a fixing member that is received in the groove and is laid with the multiple optical fibers in a given alignment state; and 
     a fixing plate that is fixed on the surface, in which the groove is formed, of the board and fixes the multiple optical fibers and the fixing members inside the groove while keeping the given alignment states of the multiple optical fibers and the fixing members. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail in conjunction with the appended drawings, wherein: 
     FIG. 1 is a perspective view showing a conventional arrayed optical fiber connector, 
     FIG. 2 is a plan view illustrating the problem of the conventional arrayed optical fiber connector, 
     FIG. 3 is a perspective view showing a arrayed optical fiber connector in a preferred embodiment according to the invention 
     FIG. 4 is a plan view showing an example of a arrayed optical fiber connector, which uses a board with a groove that has an error in manufacture, according to the invention, and 
     FIG. 5 is a plan view showing an example of a arrayed optical fiber connector, which uses optical fibers that have a dispersion in diameter, according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 3 shows a arrayed optical fiber connector in the preferred embodiment according to the invention. 
     The arrayed optical fiber connector  20  is structured such that multiple (four, in this embodiment) optical fibers  21   a ,  21   b ,  21   c  and  21   d , each of which having a core  1  and a clad  2 , are disposed in an alignment assembly  22 . For example, as the optical fibers  21   a  to  21   d , a single-mode fiber line with a diameter of 125 μm and a transmission center wavelength of 1.55 μm is used. 
     The alignment assembly  12  is composed of a nearly rectangular-solid-shaped board  23 , a fixing plate  24  that has the same form as the board  13  except having a thickness less than the board  23 , and multiple (six, in this embodiment) fixing pins (fixing members)  30   a ,  30   b ,  30   c ,  30   d ,  30   e  and  30   f.    
     The board  23  is provided with a rectangular cross-sectional groove  23   a  that contains the optical fibers  21   a  to  21   d  in alignment at its bottom and further contains stacking the fixing pins  30   a  to  30   f  on the optical fibers  21   a  to  21   d . The board  23  is, for example, of glass such as silica glass, ceramics or the like whose dimensions are 2 mm in height, 3 mm in width and 5 mm in length. Also, the fixing plate  24  is, for example, of glass such as silica glass, ceramics or the like whose dimensions are 2 mm in height, 3 mm in width and 5 mm in length. 
     The fixing pins  30   a  to  30   f  has a diameter nearly equal to that of the optical fibers  21   a  to  21   d  and a thickness nearly equal to that of the groove  23   a . The fixing pins  30   a  to  30   f  are made by carving out, e.g., a single-mode fiber line with a diameter of 125 μm and a transmission center wavelength of 1.55 μm, or are made of glass such as silica glass, ceramics or the like. 
     The groove  23   a  has a length that extends through between two sides orthogonal to its bottom, a depth that is nearly equal to the stack height of the optical fibers  21   a  to  21   d  and the fixing pins  30   a  to  31   f , and a width that is equal to the sum of the diameters of the optical fibers  21   a  to  21   d , for example, 500 μm when using a single-mode fiber line with a diameter of 125 μm and a transmission center wavelength of 1.55 μm as the optical fibers  21   a  to  21   d.    
     Inside the groove  23   a , the four optical fibers  21   a  to  21   d  are, side by side, aligned at the bottom of the groove  23   a , the three fixing pins  30   a ,  30   b  and  30   c  are laid on the optical fibers  21   a  to  21   d  so that each of them locates between adjacent two of the optical fibers  21   a  to  21   d , the two fixing pins  30   d  and  30   e  are laid on the fixing pins  30   a  to  30   c  so that each of them locates between adjacent two of the fixing pins  30   a  to  30   c , one fixing pin  30   f  is laid on the fixing pins  30   d  and  30   e  so that it locates between the fixing pins  30   d  and  30   e.    
     With such arrangement, the optical fibers  21   a  to  21   d  can be positioned inside the groove  23   a , as detailed later. Namely, the optical fibers  21   a  to  21   d , which are side by side aligned at the bottom of the groove  23   a , are contacting each other and the optical fibers  21   a  and  21   d  on both ends each are contacting the side of the groove  23   a . Therefore, the lateral movement of the optical fibers  21   a  to  21   d  is restricted, thereby the optical fibers  21   a  to  21   d  can be positioned in the lateral direction. 
     Also, the fixing pins  30   a  to  30   c , which are laid on the optical fibers  21   a  to  21   d , are contacting each other, and the fixing pins  30   a  to  30   c  are contacting the lower two optical fibers ( 21   a ,  21   b ), ( 21   b ,  21   c ), and ( 21   c ,  21   d ), respectively. Therefore, the lateral movement of the fixing pins  30   a  to  30   c  is restricted, thereby the fixing pins  30   a  to  30   c  can be positioned in the lateral direction. Furthermore, since the vertical movement of the optical fibers  21   a  to  21   d  is restricted by the upper fixing pins  30   a  to  30   c , the optical fibers  21   a  to  21   d  can be positioned in the vertical direction. 
     Also, the fixing pins  30   d  and  30   e , which are laid on the fixing pins  30   a  to  30   c , are contacting each other, and the fixing pins  30   d  and  30   e  are contacting the lower two fixing pins ( 30   a ,  30   b ) and ( 30   b ,  30   c ), respectively. Therefore, the lateral movement of the fixing pins  30   d ,  30   e  is restricted, thereby the fixing pins  30   d ,  30   e  can be positioned in the lateral direction. Furthermore, since the vertical movement of the fixing pins  30   a  to  30   c  is restricted by the upper fixing pins  30   d ,  30   e , the fixing pins  30   a  to  30   c  can be positioned in the vertical direction. 
     Further, the fixing pin  30   f , which is laid on the fixing pins  30   d ,  30   e , is contacting the lower two fixing pins ( 30   a ,  30   b ) and ( 30   b ,  30   c ), respectively. Therefore, the lateral movement of the fixing pin  30   f  is restricted, thereby the fixing pin  30   f  can be positioned in the lateral direction. Furthermore, since the vertical movement of the fixing pins  30   d ,  30   e  is restricted by the upper fixing pin  30   f , the fixing pins  30   d ,  30   e  can be positioned in the vertical direction. 
     Moreover, the uppermost fixing pin  30   f  is contacting the fixing plate  24 . Therefore, the vertical movement of the fixing pin  30   f  is restricted, thereby the fixing pin  30   f  can be positioned in the vertical direction. 
     As described above, the optical fibers  21   a  to  21   d  and the fixing pins  30   a  to  30   c  are disposed such that they are stacked forming a triangle-cross-section. Therefore, by pressing down only the fixing pin  30   f  by the fixing plate  24 , all of the optical fibers  21   a  to  21   d  and the fixing pins  30   a  to  30   c  can be pressed down and positioned. Because of this, the high-precision manufacturing of the components, especially the depth of the groove  23   a , of the arrayed optical fiber connector  20  is not necessary, which makes the manufacturing easy. In addition, the high-precision assembling, especially the positioning of the optical fibers  21   a  to  21   d  when attaching the fixing plate  24 , of the arrayed optical fiber connector  20  is not necessary, which makes the assembling easy. 
     The method of assembling the arrayed optical fiber connector  20  thus composed is explained. First, the tips of the four optical fibers  21   a  to  21   d  are, side by side, inserted into the groove  23   a  provided on the board  23 , and then the three fixing pins  30   a  to  30   c  are laid on the optical fibers  21   a  to  21   d  so that each of them locates between adjacent two of the optical fibers  21   a  to  21   d.    
     Further, the two fixing pins  30   d ,  30   e  are laid on the fixing pins  30   a  to  30   c  so that each of them locates between adjacent two of the fixing pins  30   a  to  30   c . One fixing pin  30   f  is laid on the fixing pins  30   d ,  30   e  so that it locates between the fixing pins  30   d ,  30   e.    
     Then, adhesive  25  is filled into the clearance between the groove  23   a  and the optical fibers  21   a  to  21   d  and the fixing pins  30   a  to  30   c . This adhesive  25  used is, for example, thermosetting type epoxy-system adhesives. 
     Then, the fixing plate  24  is disposed on the surface where the groove  23   a  is formed of the board  23 , brought in contact with the fixing pin  30   f , equally pressing down the fixing pin  30   f  in the direction of the groove  23   a.    
     Finally, by heating the board  23  to harden adhesive  25  while pressing the fixing plate  24 , the board  23 , the optical fibers  21   a  to  21   d , fixing pins  30   a  to  30   c  and the fixing plate  24  are integrally fixed, thereby obtaining the arrayed optical fiber connector  20 . 
     FIG. 4 is a plan view showing an example of a arrayed optical fiber connector, which uses a board with a groove that has an error in manufacture, according to the invention. In FIG. 4, like parts are indicated by like reference numerals as used in FIG.  3  and their explanations are omitted herein. 
     The board  33  has been manufactured such that the bottom of the groove  33   a  is θ°, e.g., 2°, declined to the top face. 
     In using the board  33  thus manufactured, as shown in FIG. 4, though a clearance dA occurs between the fixing pins  30   b  and  30   c , the fixing pin  30   c  is contacting the lower optical fibers  21   c ,  21   d  and is contacting the upper fixing pin  30   e . Therefore, the lateral and vertical movements are restricted, thereby no positional deviation occurs. 
     FIG. 5 is a plan view showing an example of a arrayed optical fiber connector, which uses optical fibers that have a dispersion in diameter, according to the invention. In FIG. 5, like parts are indicated by like reference numerals as used in FIG.  3  and their explanations are omitted herein. 
     The diameters Da, Db, Dc and Dd of optical fibers  31   a ,  31   b ,  31   c  and  31   d , respectively, are different from each other. For example, they are 126 μm, 127 μm, 125 μm and 124 μm, respectively. 
     In using the optical fibers  31   a  to  31   d  thus provided, as shown in FIG. 5, though clearances dB, dC and dD occur between the fixing pins ( 30   a ,  30   b ), ( 30   b ,  30   c ) and ( 30   d ,  30   c ), respectively, the fixing pin  30   a  is contacting the lower optical fibers  31   a ,  31   b  and is contacting the upper fixing pin  30   d . Therefore, the lateral and vertical movements are restricted, thereby no positional deviation occurs. Also, for the other fixing pins  30   b  to  30   e , in like manner, the lateral and vertical movements are restricted, thereby no positional deviation occurs. 
     As described above, the fixing pins  30   a  to  30   f  absorbs the error in manufacture of the groove  33   a  or the dispersion in diameter of the optical fibers  31   a  to  31   d  so that the optical fibers  21   a  to  21   d  or  31   a  to  31   d  can be all fixed. Thus, the positional deviation of the optical fibers  21   a  to  21   d  or  31   a  to  31   d  can be easily prevented. 
     Although the invention has been described with respect to specific embodiment for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modification and alternative constructions that may be occurred to one skilled in the art which fairly fall within the basic teaching here is set forth.