Appeal No. 1997-4033
Application No. 08/589,584
LD, which is attractive for Wavelength Division Multiplex
(WDM) systems and coherent optical transmission systems.
Sasaki also explains that these devices include portions
having different band gap energies: "In these devices, the
active layer and the passive waveguide layer, where bandgap
energy of each layer is different, should be smoothly joined
along the waveguide direction" (Sasaki at 373, 2d col.). In
the DFB-LD/modulator (Fig. 8), the mask stripe width was 10 Fm
for the DFB-LD region and 4 Fm for the modulator region
(Sasaki at 377, 2d col.). In the three-section tunable DBR-LD
(Fig. 11), the mask stripe was 10 Fm for the active region and
4 Fm for the other regions (id. at 378, 2d col.).
The examiner's case for the obviousness of the subject
matter of claim 22 is as follows (Answer at 3):
Rolland teaches a Mach-Zehnder modulator structure
including a thick width Y-portion and two thin width
active region arms. The thick width portion is disclosed
as 4 micron[s] wide. . . .
Sasaki teaches on page 378 a mask stripe width of 10
micron[s] in the active region and 4 micron[s] in the
other regions. Refer to Figure 11. On page 374 it is
clearly taught that a wide mask (or narrow width
modulator) results in thick MQW layers which results in
10
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