Appeal No. 1997-4033 Application No. 08/589,584 Claim 22, the only independent claim, reads as follows: 22. A Mach-Zehnder optical modulator having first and second passive regions and an active region between said first and second passive regions, said Mach-Zehnder optical modulator comprising: a semiconductor substrate extending over said first and second passive regions and said active region; a bottom electrode extending on an entire part of a bottom surface of said semiconductor substrate; a first cladding layer extending on an entire part of a top surface of said semiconductor substrate; a ridge-shaped optical wave-guide having: a Y-shaped branching passive wave-guide section on said first passive regions [sic, region]; a Y-coupling passive wave-guide section on said second passive regions [sic, region]; and two parallel straight phase modulator sections on said active region; wherein said ridge-shaped optical wave-guide comprises: a buffer layer provided on said first cladding layer; a multiple quantum well optical wave-guide layer provided on said buffer layer, said multiple quantum well optical wave- guide layer being grown by a metal organic vapor phase epitaxy using dielectric stripe masks having a large width in said active region and a small width in said first and second passive regions so that said multiple quantum well optical wave-guide layer provided on said first and second passive regions has a thickness larger than that provided on said active region and so that said multiple quantum well optical wave-guide layer provided on said first and second passive regions has a band gap wavelength smaller than that provided on said active region; a second cladding layer provided on said multiple quantum well optical wave-guide layer; 7Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 NextLast modified: November 3, 2007