Ex parte KOMATSU - Page 9

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

          to be thinner in the active region than in the passive                      
               Rolland discloses a Mach-Zehnder modulator which includes              
          a "singlemode" section that is 2 Fm wide followed by a                      
          "triple-moded" section that is 4 Fm wide, which branches into               
          a pair of S-rib waveguides 2 Fm wide and 3 Fm deep, which are               
          rejoined by another 4 Fm branching section, which is followed               
          by a final 2 Fm wide section (Rolland at 371, 2d col.).                     
          Rolland does not explain how much of the 3 Fm depth of the rib              
          sections is occupied by the MQW structure.  Nor does Rolland                
          indicate that the MQW structure has different thicknesses in                
          the active and passive sections.                                            
               As already noted, Sasaki explains that MQW thickness and               
          band gap wavelength are a function of the width of the mask                 
          stripes used to form the MQW layers.  Sasaki explains (at 372-              
          73) that this bandgap energy control technique can be used to               
          form smooth junctions between active and passive waveguide                  
          layers in various types of monolithically integrated photonic               
          devices, such as (1) a DFB-LD (Distributed Feedback Laser                   
          Diode) monolithically integrated with an optical modulator and              
          (2) a three-section tunable DBR (Distributed Bragg Reflector)-              


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