Patent ID: 7088892

Claim:
A Y-branch normally dark digital optical switch or normally dark variable optical attenuator (ND-DOS/VOA) comprising an input waveguide segment, an output waveguide segment, an exhaust waveguide segment, a transition waveguide segment, a heater disposed proximate to said transition waveguide segment and said output waveguide segment; said transition segment being disposed between said input waveguide segment, and said output and exhaust waveguide segments; said output waveguide segment and said exhaust waveguide segment being divergingly disposed with respect to said transition waveguide segment; said output waveguide segment being of a width and height that is within −50% to +100% of the width and height, respectively, of said input waveguide segment; said transition waveguide segment being geometrically asymmetric with respect to the longitudinal axis of said input waveguide segment; said exhaust waveguide segment and said output waveguide segment being characterized by a width ratio of at least 2:1; wherein said input, output, exhaust, and transition waveguide segments comprise an organic polymer or silica; and with the proviso that said Y-branch ND-DOS/VOA further comprises a lateral displacement between said heating means and said output waveguide segment when said input, output, exhaust, and transition waveguide segments comprise an organic polymer.