Normally dark Y-branch digital optical switches and variable optical attentuators
View Patent ↗The present invention is directed to Y-branch digital optical switching and optical attenuator devices, which enhance the security of optical communications channels in the event of an electrical power loss.
1. 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.
2. The ND-DOS/VOA of claim 1 in the form of an ND-DOS.
3. The ND-DOS/VOA of claim 1 wherein said width ratio is at least 5:1.
4. The ND-DOS/VOA of claim 1 wherein said width ratio is at least 15:1.
5. The ND-DOS/VOA of claim 1 wherein said width ratio is at least 25:1.
6. The ND-DOS/VOA of claim 1 wherein the heater is an electrical resistance heater.
7. The ND-DOS/VOA of claim 1 comprising an organic polymer.
8. The ND-DOS/VOA of claim 1 further comprising a lateral shift of said transition waveguide segment with respect to said input waveguide segment of at least 3 times the width of said input waveguide segment at the output end thereof.
9. The ND-DOS/VOA of claim 7 wherein said lateral shift is at least ten times the width of said input waveguide segment at the output end thereof.
10. The ND-DOS/VOA of claim 1 wherein each of said waveguide segments comprise a core and a cladding, and wherein the refractive index of said core and cladding is uniform throughout said ND-DOS/VOA.
11. The ND-DOS/VOA of claim 1 wherein each of said waveguide segments comprise a core and a cladding, and wherein the refractive index of the core of said exhaust waveguide segment is higher than the refractive index of the core of said output waveguide segment.
12. The ND-DOS/VOA of claim 1 wherein said transition waveguide segment is characterized by a length of 1.5 to 2.5 millimeters.
13. The ND-DOS/VOA of claim 1 wherein said transition waveguide segment is characterized by a core width of 10 to 200 micrometers.
14. The ND-DOS/VOA of claim 1 wherein said exhaust waveguide segment is in the form of a parallelogram.
15. The ND-DOS/VOA of claim 1 wherein the width of said exhaust waveguide segment grows linearly and monotonically wider in the direction of propagation.
16. The ND-DOS/VOA of claim 1 wherein said exhaust waveguide segment is clipped in the transition waveguide segment.
17. The ND-DOS/VOA of claim 1 wherein said exhaust waveguide segment ends before the edge of the PLC chip on which it is mounted.
18. The ND-DOS/VOA of claim 17 further comprising an angled mirror at the termination of said exhaust waveguide.
19. The ND-DOS/VOA of claim 1 wherein said exhaust waveguide segment is characterized by curved sides.
20. The ND-DOS/VOA of claim 1 wherein said exhaust waveguide segment is in the form of the component waveguide segments and the heater that constitute the ND-DOS/VOA of the invention are smoothly curved.