Patent Publication Number: US-2013236087-A1

Title: Testing method and testing device for laser diode die

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to laser diodes (LDs) and, particularly, to a testing method and testing device for an LD die. 
     2. Description of Related Art 
     LDs include an LD die and a package packaging the LD die. An electro-optical conversion property of the LD, which determines if the LD is qualified, mainly depends on an electro-optical conversion property of the LD die. However, a quality of the LD is typically tested after being packaged. As such, unqualified LD dies cannot be avoided from being packaged, which wastes time and materials. Additionally, current testing on the LD typically involves manual operation. For example, operators set values of electric current applied to the LD, measure the respective voltage values across the LD and power values of light emitted from the LD, and then calculate an electro-optical characteristic curve for the LD. Such testing is carried out under varying criteria, e.g., variances in skill level and in standards of individual operators, and is an inefficient use of man-power and resources. 
     Therefore, it is desirable to provide a testing method and testing device for an LD die which can overcome the above-mentioned shortcomings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart of a testing method for an LD die according to an embodiment. 
         FIG. 2  is a schematic view of a testing device for the LD die according to the embodiment. 
         FIG. 3  is a schematic view of a controller of the testing device of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the disclosure will be described in detail, with reference to the accompanying drawings. 
       FIG. 1 , is a testing method, according to one embodiment. The testing method tests if an LD die  20  (see  FIG. 2 ) is qualified with a predetermined electro-optical property. If qualified the LD die  20  is packaged into an LD. The testing method includes the following steps S 1 -S 7 . 
     In step S 1 , holding the LD die  20 . 
     In step S 1   a , determining whether cosmetic defects of the LD die  20  need to be detected. If it is determined that the cosmetic defects of the LD die  20  do not need to be detected, the testing method goes to step S 2 . 
     In step S 2 , determining the electric current to be applied to the LD die  20  according to the predetermined electro-optical property. The electric current increases with a fixed increment when a sequence of current values is applied to the LD die  20 . The electric current is characterized by the current values. 
     In step S 3 , obtaining control parameters. 
     In step S 4 , driving the LD die  20  to emit light according to the control parameters by applying the electric current to the LD die  20 . 
     In the step S 5 , measuring a sequence of voltage values across the LD die  20  and a sequence of power values of the light emitted from the LD die  20 , the sequence of voltage values and the sequence of power values corresponding to the sequence of current values, according to the control parameters. 
     In the step S 6 , using the sequence of current values, the sequence of voltage values, and the sequence of power values to generate a table  110  and a graph  112  (see  FIG. 3 ). 
     In the step S 7 , determining if the LD die  20  is qualified to the predetermined electro-optical property using the table  110  and/or the graph  112 . 
       FIG. 2 , shows a testing device  10  for implementing the testing method of  FIG. 1 . The testing device  10  includes a chuck  12 , a current source  14 , a support  16 , an optical power meter  18 , and a controller  100 . 
     The LD die  20  is held by the chuck  12 . That is, the step S 01  can be carried out with the chuck  12 . However, in other embodiments, the LD die  20  can be held by other devices/methods. 
     The current source  14  is configured for supplying the electric current and has a voltage meter  142 . 
     The support  16  is positioned on the chuck  12  and includes a first cantilever  162  extending above the chuck  12 . 
     The optical power meter  18  includes a photo detector  182  and a power meter  184 . The photo detector  182  is positioned on the first cantilever  162 , facing the chuck  12 . The power meter  184  is electrically connected to the photo detector  182 . 
     The controller  100  is electrically connected to the current source  14  and the optical power meter  18 . The controller  100  includes a calculation unit  102 , a user interface  104 , a control unit  106 , and a data generation unit  108 . 
     The calculation unit  102  is configured for calculating the sequence of current values according to the predetermined electro-optical property. That is, the step S 2  can be carried out by the calculation unit  102 . 
     The user interface  104  is configured for receiving user inputs and thus determining the control parameters of the current source  14  and the optical power meter  18  corresponding to the user inputs. That is, the step S 3 , can be carried out by the user interface  104 . 
     The control unit  106  is configured for controlling the current source  14  to supply the electric current and measure the sequence of voltage values, and controlling the optical power meter  18  to measure the sequence of power values, according to the control parameters. That is, the current source  14  and the control unit  106  cooperatively implement the step S 4 . The voltage meter  142 , the optical power meter  18 , and the control unit  106  cooperatively implement the step S 5 . 
     The data generation unit  108  is also configured for processing the sequence of current values, the sequence of voltage values, and the sequence of power values and thus generating the table  110  and the graph  112  both of which indicates the electro-optical property of the LD die  20 . That is, the data generation unit  108  and the user interface  104  cooperatively implement the step S 6 . 
     As such, an unqualified LD die can be found and thus, avoid being packaged which saves time and materials. In addition, the testing can be implemented efficiently and under uniform criteria by the testing method and testing device. 
     The current source  14  includes two probes  144  for contacting electrodes of the LD die  20  and supplying the electric current cross the LD die  20 . The current values can be 1 mA, 2 mA, 3 mA . . . 20 mA. The voltage meter  142  is integrated in the current source  14 . The sequence of voltages can be measured through the probes  144 . 
     The support  16  can further include a rotary plate  164 . The first cantilever  162  extends from the rotary plate  164 . The photo detector  182  can be positioned to directly face the LD die  20  by rotating the rotary plate  164 . 
     The support  16  also includes a second cantilever  166  and a camera module  168 . The second cantilever  166  also extends from the rotary plate  164 . The camera module  168  is positioned on the second cantilever  166  and can be positioned to directly face the LD die  20  by rotating the rotary plate  164 . The manufacturing method further includes the following steps S 12   a , S 12   b , S 12   c.    
     In step S 12   a , capturing an image of the LD die  20  with the camera module  168 . If it is determined that the cosmetic defects of the LD die  20  need to be detected, the camera module  168  is positioned to directly face the LD die  20  by rotating the rotary plate  164  and is actuated to capture the image of the LD die  20 . 
     In step S 12   b , displaying the image of the LD die  20 . 
     In step S 12   c , analyzing if the LD die  20  has the cosmetic defects based upon the image of the LD die  20 . If the LD die  20  has no cosmetic defects, the testing method goes to the step S 2 . Otherwise, the LD die  20  is rejected and is not packaged. 
     Particular embodiments are shown here and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.