Abstract:
An optical coupling element includes a first side surface and an upper surface. The upper surface defines a first cavity and a tapering hole which permits the insertion and precise fixing in place with adhesive of an optical fiber, without any gap or play in the attachment which would allow misalignment between the optical fiber and a light coupling lens.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an optical coupling element and an optical fiber connector using the same. 
     2. Description of Related Art 
     Optical fiber connectors typically include a blind hole behind a lens. The blind hole is configured to receive an optical fiber. The optical fiber inserted into the blind hole needs be fixed in place by adhesive. A typical method for adhering the optical fiber in the blind hole is to firstly insert an end of the optical fiber into the blind hole, and then to inject the adhesive in the opening of the blind hole while performing further insertion of the optical fiber into the blind hole to make the adhesive fill between a sidewall of the optical fiber and an inner wall of the blind hole, finally to insert the optical fiber further into the blind hole to accomplish the assembly process. However, this method costs time and does not permit the adhesive to completely surround the sidewall of the optical fiber. This may result in a weak adhesion of the optical fiber in the blind hole and more likely to allow the optical fiber to be misaligned with the optical axis of the lens. 
     Therefore, it is desirable to provide an optical coupling element and an optical fiber connector which can overcome the above-mentioned limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. 
       The FIGURE is a cross-sectional view of an optical fiber connector, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The drawing shows an optical fiber connector  100 , according to an embodiment. The optical fiber connector  100  includes a printed circuit board (PCB)  10 , an optical coupling element  20  positioned on the PCB  10 , an optical fiber  30  assembled into the optical coupling element  20 , an optical adhesive  40  and a filling member  50 . 
     The PCB  10  includes a supporting surface  101  and a rear surface  102  opposite to the supporting surface  101 . A photoelectric conversion chip  13 , which in the embodiment can be a laser diode or a photo diode, is positioned on the supporting surface  101 . The PCB  10  contains various circuits (not shown) that connect with the photoelectric conversion chip  13 . 
     The optical coupling element  20  includes a first side surface  21 , an upper surface  22  and a lower surface  23  opposite to the upper surface  22 . The upper surface  22  is substantially parallel with the lower surface  23 . The first side surface  21  perpendicularly connects the upper surface  22  and the lower surface  23 . 
     The optical coupling element  20  defines a recess  210  formed in a border of the upper surface  22  and the first side surfaces  21 . The optical coupling element  20  also defines a first cavity  221  in the upper surface  22 . The first cavity  221  includes a reflecting surface  2211 . An included angle between the upper surface  22  and the reflecting surface  2211  is about 45 degrees. The upper surface  22  defines a blind hole  220  adjacent to the first cavity  221 . The blind hole  220  includes a vertical surface  220   a  substantially perpendicular to the upper surface  22  and the lower surface  23 . 
     The blind hole  220  and the first cavity  221  are spaced by a distance. A fixing portion  20   a  is formed between the blind hole  116  and the recess  210 . The fixing portion  20   a  includes a first sidewall  201  and a second sidewall  202  away from the first sidewall  201 . The first sidewall  201  communicates with the recess  210  and is opposite to the vertical surface  220   a . The second sidewall  202  communicates with the blind hole  220 . The blind hole  220  is located between the vertical surface  220   a  and the second sidewall  202 . The fixing portion  20   a  defines a tapering hole  2011  extending through first sidewall  201  to the second sidewall  202 . The tapering hole  2011  communicates with the blind hole  220  and the recess  210 . A central axis of the tapering hole  2011  is substantially perpendicular to a central axis of the blind hole  220 . 
     The optical coupling element  20  defines a receiving cavity  231  in the lower surface  23 , a bottom surface  2311  of the first cavity  231  forms a light coupling lens  24 . In the embodiment, the light coupling lens  24  is a convex lens integrally formed with the optical coupling element  20 . The lower surface  23  is on the supporting surface  101  of the PCB  10 , with the photoelectric conversion chip  13  being received in the receiving cavity  231 , such that the light coupling lens  24  faces and aligns with the photoelectric conversion chip  13  and also aligns with the reflecting surface  2211 . An included angle between the bottom surface  2311  and the reflecting surface  2211  is about 45 degrees. An included angle between an optical axis of the light coupling lens  24  and the reflecting surface  2211  is therefore about 45 degrees. 
     In the embodiment, the tapering hole  2011  is funnel-shaped. The tapering hole  2011  has a tapering portion adjacent to the second sidewall  210 . The tapering portion is tapered along a far-to-near direction relative to the second sidewall  202 . In the embodiment, a diameter of an end of the tapering hole  2011  close to the first sidewall  201  is larger than a diameter of the optical fiber  30 , a diameter of the other end of the tapering hole  2011  close to the second sidewall  202  is equal to the diameter of the optical fiber  30 . The optical fiber  30  is inserted into the tapering hole  2011 , with an end of the optical fiber  30  being received in the blind hole  220 . In the embodiment, the optical fiber  30  and the vertical surface  220   a  are spaced by a distance, as such, a receiving hole  220   b  is formed between the vertical surface  220   a  and the optical fiber  30 . 
     In the embodiment, the optical adhesive  40  is an optically clear resin (OCR) adhesive. The optical adhesive  40  is filled into the receiving hole  220   b  to firmly attach the optical fiber  30  onto the vertical surface  220   a  without any gap or space. 
     After injecting the optical adhesive  40 , both the blind hole  220  and the recess  210  are filled by the filling member  50 . In the embodiment, the filling member  50  is adhesive cured by ultraviolet light (UV adhesive). 
     In use, when the photoelectric conversion chip  13  is a laser diode, light emitted from the photoelectric conversion chip  13  is directed into the optical coupling element  20  by the light coupling lens  24 , and the light path is reflected about 90 degrees from the original path by the reflecting surface  2211 . The light is thus finally reflected into the optical fiber  30  by the reflecting surface  2211 . When the photoelectric conversion chip  13  is a photo diode, a process of the photo diode receiving light is the reverse of that of the laser diode emitting light. 
     It will be understood that the above particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiment thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the possible scope of the disclosure but do not restrict the scope of the disclosure.