Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical switch adapted as an essential part in a WDM optical communication network, and more particularly to an apparatus for switching optical signals of multiple channels and a method for manufacturing the apparatus. 
   2. Description of the Related Art 
   Generally, an optical switch serves to change a route of an optical signal transmitted through an optical fiber in a Wavelength Division Multiplexing (hereinafter, referred to as “WDM”) optical communication network. The optical switch has been recently developed to employ a Micro Electro Mechanical System (hereinafter, referred to as “MEMS”) technique. 
     FIGS. 1   a  and  1   b  are schematic views respectively illustrating a structure and a switching operation of a conventional MEMS optical switch. 
   With reference to  FIGS. 1   a  and  1   b , the conventional MEMS optical switch employs a method in which light emitted from an input terminal optical fiber due to the displacement of an actuator having a MEMS structure is reflected by a micro mirror and then transmitted in at least two directions. 
   As shown in  FIGS. 1   a  and  1   b , the conventional MEMS optical switch comprises an input terminal optical fiber  11  to which an optical signal to be switched is inputted, a first output terminal optical fiber  12  arranged with the input terminal optical fiber  11  in a straight line, and a second output terminal fiber  13  arranged perpendicularly to the input terminal optical fiber  11 . The conventional MEMS optical switch further comprises a micro mirror  14  located between the input terminal optical fiber  11  and the first and second output terminal optical fibers  12  and  13  for changing the direction of the inputted optical signal by means of reflection, and an actuator  15  for driving the micro mirror  14 . 
   Hereinafter, a principle of the MEMS optical switch for switching the optical signal will be described in detail. As shown in  FIG. 1   a , the actuator  15  drives the micro mirror  14  such that the micro mirror  14  is moved to the opposite direction of the second output terminal optical fiber  13 . Then, the optical signal inputted to the input terminal optical fiber  11  travels in parallel, and goes ahead through the first output terminal optical fiber  12 . 
   On the other hand, as shown in  FIG. 1   b , the actuator  15  drives the micro mirror  14  such that the micro mirror  14  is moved to the direction of the second output terminal optical fiber  13  and located between the input terminal optical fiber  11  and the first and second output terminal optical fibers  12  and  13 . Then, the optical signal inputted from the input terminal optical fiber  11  is reflected by the micro mirror  14  and goes ahead through the second output terminal optical fiber  13 . The conventional MEMS optical switch switches the optical signal using the above principle, thereby having advantages such as an increased switching speed and a reduced rate of power consumption. 
   In order to process an optical signal with a large capacity so as to satisfy the rapid increase of subscribers of the optical communication network, a technique for providing signal-switching to multiple channels is required. However, the conventional MEMS optical switch using the micro mirror and the actuator has problems in that it is difficult to process the multiple channels due to characteristics of the optical signal and difficulty in packaging. 
   SUMMARY OF THE INVENTION 
   Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical switch comprising multiple channels for effectively processing an optical signal with a large capacity and a method for manufacturing the optical switch. 
   It is another object of the present invention to provide an optical switch for supplying an optical signal with uniform optical performance throughout optical routes of multiple channels and a method for manufacturing the optical switch. 
   In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a multi-channel optical switch comprising: a supporter; an input terminal optical fiber fixed to the supporter for inputting an optical signal to be switched therethrough; multiple output terminal optical fibers fixed to the supporter for outputting the optical signal inputted through the input terminal optical fiber therethrough; multiple micro mirrors for reflecting the optical signal inputted through the input terminal optical fiber and then for directing the optical signal to a designated output terminal optical fiber among the multiple output terminal optical fibers; and multiple actuators respectively connected to the micro mirrors for adjusting the positions of the micro mirrors so that the optical signal is reflected by the micro mirrors. 
   Preferably, the multi-channel optical switch may further comprise multiple lenses fixed to the supporter and respectively separated from the optical fibers by a designated distance for collimating the optical signal transmitted and received through the optical fibers so that the optical signal has uniform optical performance throughout a constant optical path. 
   Further, preferably, the multi-channel optical switch may further comprise a housing surrounding an upper portion of the supporter. 
   In accordance with another aspect of the present invention, there is provided a method for manufacturing a multi-channel optical switch comprising the steps of: (a) forming grooves for receiving multiple optical fibers, multiple lenses, multiple micro mirrors and multiple actuators in a supporter; (b) fixing the lenses, which are polished to adjust their sizes and incident surfaces, to the supporter; (c) inserting the optical fibers into the grooves of the supporter, said optical fibers being respectively spaced from the lenses by a designated air gap so that the lenses have uniform optical performance throughout a designated optical path; (d) finely adjusting the inserted optical fibers, and then fixing the adjusted optical fibers to the supporter; and (e) arranging the micro mirrors and the actuators at corresponding positions on the supporter so that the optical signal is reflected by the micro mirrors toward a designated channel. 
   Preferably, the method may further comprise the step of (f) surrounding an upper portion of the supporter with a housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1   a  is a schematic view illustrating a structure of a conventional MEMS optical switch; 
       FIG. 1   b  is a schematic view illustrating a switching operation of the conventional MEMS optical switch; 
       FIG. 2  is a schematic view of a structure of a multi-channel optical switch in accordance with an embodiment of the present invention; 
       FIGS. 3   a  to  3   d  are schematic views illustrating a switching operation of the multi-channel optical switch in accordance with the embodiment of the present invention; and 
       FIG. 4  is a flow chart illustrating a process for manufacturing the multi-channel optical switch in accordance with the embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Now, embodiments of the present invention will be described in detail with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. 
     FIG. 2  is a schematic view of a structure of a multi-channel optical switch in accordance with an embodiment of the present invention. 
   With reference to  FIG. 2 , the multi-channel optical switch comprises an input terminal optical fiber  200 , multiple output terminal optical fibers  201  to  204 , lenses  210  to  214  in number corresponding to the number of the output terminal optical fibers  201  to  204 , micro mirrors  222  to  224 , and actuators  232  to  234 . The input terminal optical fiber  200 , the output terminal optical fibers  201  to  204 , the lenses  210  to  214 , the micro mirrors  222  to  224 , and the actuators  232  to  234  are located on a supporter  240  made of a silicon wafer. 
   Although this embodiment of the present invention comprises four channels A, B, C and D, the multi-channel optical switch may comprise channels having the number of more than four. 
   An optical signal to be switched is inputted to the input terminal optical fiber  200 . The first output terminal optical fiber  201  and the input terminal optical fiber  200  are arranged in a straight line. The second, third and fourth output terminal optical fibers  202 ,  203  and  204  are perpendicular to the input terminal optical fiber  200  so that the channels B, C and D are located between the input terminal optical fiber  200  and the first output terminal optical fiber  201 . 
   The micro mirrors  222 ,  223  and  224  for changing the direction of the optical signal are formed such that the optical signal inputted through the input terminal optical fiber  200  is reflected by the micro mirrors  222 ,  223  and  224  and then outputted through the second, third and fourth output terminal optical fibers  202 ,  203  and  204 . Each of the micro mirrors  222 ,  223  and  224  is oblique to the perpendicular plane formed by the input terminal optical fiber  200  and the corresponding one of the second, third and fourth output terminal optical fibers  202 ,  203  and  204 , at an inclination of approximately 45 degrees. 
   The actuators  232 ,  233  and  234  are formed so as to allow the micro mirrors  222 ,  223  and  224  to perform a switching operation. The micro mirrors  222 ,  223  and  224  are respectively attached to one end of each of the actuators  232 ,  233  and  234 , and operated for switching the optical signal by the control of the actuators  232 ,  233  and  234 . Here, the micro mirrors  222 ,  223  and  224 , and the actuators  232 ,  233  and  234  are designed such that they are separately produced and then combined together, or integrally produced. 
   In accordance with another embodiment of the present invention, the lenses  210 ,  211 ,  212 ,  213  and  214  for collimating the optical signal are formed on the supporter  240  made of the silicon wafer. For example, the first lens  210  serves to allow the optical signal, which is inputted through the input terminal optical signal  200  and then outputted through the first output terminal optical signal  201  in the structure of the switching system shown in  FIG. 2 , to uniformly travel in parallel without waveform distortion by a designated distance. As described above, the switching system of this embodiment of the present invention provides the optical signal having uniform characteristics throughout optical traveling paths among the channels A, B, C and D and optical performance (insertion loss, PDL, and return loss) in an allowable tolerance range to the channels A, B, C and D. That is, as shown in  FIG. 2 , although there is a difference in the distance of the optical path between one end of the input terminal optical fiber  200  and each of the channels B, C and D perpendicular to the input terminal optical fiber  200 , the optical performance of the optical signal transmitted to the channels B, C and D is uniformly maintained. 
     FIGS. 3   a  to  3   d  are schematic views illustrating a switching operation of the multi-channel optical switch in accordance with one embodiment of the present invention. Here, the optical traveling path between the input terminal optical fiber  200  between the first output terminal optical fiber  201  is defined as “a main optical traveling path”. 
   With reference to  FIG. 3   a , in order to output the optical signal, inputted through the input terminal optical fiber  200 , via the channel A, all of the actuators  232 ,  233  and  234  are operated so that the micro mirrors  222 ,  223  and  224  are retracted from the main optical traveling path. Accordingly, the optical signal inputted through the input terminal optical fiber  200  goes straight ahead along the main optical traveling path, and then is outputted to the channel A. 
   With reference to  FIG. 3   b , in order to output the optical signal, inputted through the input terminal optical fiber  200 , via the channel B, the actuators  232 ,  233  and  234  are operated so that the first micro mirror  222  is positioned on the main optical traveling path. Then, the optical signal inputted through the input terminal optical fiber  200  is reflected by the first micro mirror  222 , and is then outputted to the channel B. 
   In the same manner as  FIG. 3   b , with reference to  FIG. 3   c , in case that the first micro mirror  222  is retracted from the main optical traveling path and the second micro mirror  223  is positioned on the main optical traveling path, the optical signal inputted through the input terminal optical fiber  200  is reflected by the second micro mirror  223 , and is then outputted to the channel C. Further, with reference to  FIG. 3   d , in case that the first and second micro mirrors  222  and  223  are retracted from the main optical traveling path and the third micro mirror  224  is positioned on the main optical traveling path, the optical signal inputted through the input terminal optical fiber  200  is reflected by the third micro mirror  224 , and is then outputted to the channel D. 
     FIG. 4  is a flow chart illustrating a process for manufacturing the multi-channel optical switch in accordance with one embodiment of the present invention. 
   First, in step  402 , grooves for receiving optical fibers, lenses, micro mirrors and actuators are formed in a supporter made of a silicon wafer. 
   In step  404 , the lenses are polished to adjust their sizes and incident surfaces, and then fixed to the supporter. Here, an epoxy is adapted to fix the lenses to the supporter. 
   In step  406 , optical fibers, whose ends are polished at an angle of 8 degrees to the lenses, are inserted into the grooves of the supporter. Here, the optical fibers are respectively spaced from the lenses by a designated air gap so that the lenses have uniform optical performance throughout a designated optical path. 
   In step  408 , the inserted optical fibers are finely adjusted, and then fixed to the supporter. 
   In step  410 , the micro mirrors and the actuators are respectively located at corresponding positions on the supporter. 
   In step  412 , in order to protect the above components of the manufactured optical switch from the outside, the upper surface of the supporter is surrounded by a housing. Thereby, manufacture of the optical switch in accordance with the embodiment of the present invention is completed by the above-described steps. 
   As apparent from the above description, the present invention provides an optical switch comprising multiple channels for effectively processing an optical signal with a large capacity, and a method for manufacturing the optical switch. 
   Further, the optical switch supplies an optical signal with uniform optical performance throughout optical routes of multiple channels, thereby being improved in terms of communicating performance. 
   Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Technology Category: g