Ex parte KOMATSU - Page 3

          Appeal No. 1997-4033                                                        
          Application No. 08/589,584                                                  

               voltage for the wave-guide is reduced when the band gap                
               wavelength of the wave-guide material approaches the                   
               wavelength of the incident light; however, in that                     
               condition, propagation loss from the wave-guide is high                
               (see page 4, lines 8-17 of the specification).                         
          The Brief (at 2-3) contains the following description of the                
          structure of the invention, which correctly states that a                   
          wider mask stripe produces a higher band gap wavelength but                 
          appears to incorrectly state that the wider mask stripe and                 
          higher band gap wavelength are associated with a thinner MQW                
                         The present invention achieves [the above-noted]             
                    previously conflicting aims by forming the optical                
                    wave-guide as a multiple quantum well (MQW)                       
                    structure having controlled thickness in the central              
                    active region relative to the terminal passive                    
                    regions.  In particular, the MQW structure is                     
                    relatively thinner in the central active region and               
                    relatively thicker in the terminal passive regions,               
                    such that, correspondingly, the band gap wavelength               
                    of the optical wave-guide is relatively higher in                 
                    the active region and relatively lower in the                     
                    passive regions.  This allows the band gap                        
                    wavelength in the active region to be set to a value              
                    desirably close to that of the incident light which               
                    will pass through the wave-guide, while keeping the               
                    band gap wavelength in the passive regions at a                   
                    desirably low level to minimize wave-guide loss. The              
                    controlled variation in the thickness of the optical              
                    wave-guide structure is achieved by forming the MQW               
                    layers by a technique termed Metal Organic Vapor                  
                    Phase Epitaxy (MOVPE), using a mask stripe pattern                
                    as shown for example in present Fig. 3.  That is,                 
                    the relatively wider mask stripes 201 in active                   


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