Photonic pressure sensor
A sensor. In some embodiments, the sensor includes a first waveguide, a flexible support element, and a second waveguide. A first portion of the first waveguide may be supported by the flexible support element and separated by a first gap from a second portion of the first waveguide. The flexible support element may be capable of bending so as to cause an effective index of refraction of the first waveguide to change. The first waveguide may be coupled to the second waveguide through a second gap, the second gap being at an end of the first waveguide and an end of the second waveguide.
1. A sensor, comprising:
a silicon-on-insulator wafer, comprising:
a silicon substrate,
a buried oxide (BOX) layer above the silicon substrate, and
a silicon device layer above the BOX layer and having a cavity formed therein;
a first waveguide comprising a first portion and a second portion, the second portion being a portion of the silicon device layer, and the first portion being positioned in the cavity and above the second portion;
a flexible support element coupled to the first portion of the first waveguide, extending over the cavity, and configured to move between an unbent state and a bent state;
a second waveguide, the second waveguide being a portion of the silicon device layer; and
a third waveguide, the third waveguide being a portion of the silicon device layer,
the first portion of the first waveguide being suspended in the cavity from the flexible support element and configured, when the flexible support element is in the unbent state, to be separated by a first gap from the second portion of the first waveguide, the first gap being between a bottom surface of the first portion and a top surface of the second portion,
the flexible support element being capable of bending so as to cause an effective index of refraction of the first waveguide to change,
the first waveguide being optically coupled to the second waveguide through a second gap, the second gap being between a first end of the first waveguide and an end of the second waveguide and physically separating the first and second waveguides in a longitudinal direction that is parallel to a direction of propagation of input light, and
the first waveguide being coupled to the third waveguide through a third gap, the third gap being between a second end of the first waveguide and an end of the third waveguide and physically separating the first and third waveguides in the longitudinal direction.
2. The sensor of claim 1 , wherein the first waveguide and the second waveguide are aligned along a shared plane.
3. The sensor of claim 1 wherein the second waveguide is composed of crystalline silicon.
4. The sensor of claim 1 , wherein the second gap is oblique to the first waveguide and to the second waveguide.
5. The sensor of claim 1 , wherein the flexible support element is a bridge across the cavity.
6. The sensor of claim 1 , wherein the first portion of the first waveguide is composed of amorphous silicon.
7. The sensor of claim 1 , wherein the first portion of the first waveguide is composed of crystalline silicon.
8. The sensor of claim 1 , wherein the second portion of the first waveguide is composed of crystalline silicon.
9. The sensor of claim 1 , wherein the second portion of the first waveguide is a slab.
10. The sensor of claim 1 , wherein the second portion of the first waveguide comprises a rib.
11. The sensor of claim 10 , wherein the second portion of the first waveguide comprises a slab, the rib of the second portion of the first waveguide being on the slab.
12. The sensor of claim 1 , wherein the flexible support element is composed of silicon nitride.
13. The sensor of claim 1 , comprising a Mach Zehnder interferometer having a first arm and a second arm, the first waveguide being a portion of the first arm, and the second waveguide being a portion of the first arm.
14. The sensor of claim 1 , wherein, when the flexible support element is unbent, the first gap has a width greater than 1 nm and less than 50 nm.
15. The sensor of claim 1 , wherein the second gap has a width greater than 5 nm and less than 100 nm.
16. The sensor of claim 1 , further comprising a hermetic seal that seals the cavity.
17. A sensor, comprising:
a silicon-on-insulator wafer, comprising:
a silicon substrate,
a buried oxide (BOX) layer above the silicon substrate, and
a silicon device layer above the BOX layer and having a cavity formed therein;
a ring resonator, comprising:
a first waveguide comprising a first portion of the ring resonator and being positioned in the cavity, and
a second waveguide comprising a second portion of the ring resonator and coupled to the first waveguide through each of two gaps between two ends of the first waveguide and two ends of the second waveguide;
a flexible support element coupled to the first waveguide, extending over the cavity, and configured to move between an unbent state and a bent state; and
a third waveguide, the third waveguide being a portion of the silicon device layer,
the first waveguide being a suspended waveguide comprising a first waveguide portion and a second waveguide portion,
the first waveguide portion of the first waveguide being suspended in the cavity from the flexible support element and configured, when the flexible support element is in the unbent state, to be separated from the second waveguide portion by a first gap between a bottom surface of the first waveguide portion and a top surface of the second waveguide portion,
the flexible support element being capable of bending so as to cause an effective index of refraction of the ring resonator to change,
the third waveguide being a solid waveguide,
the ring resonator being coupled to the third waveguide through a second gap between a sidewall of the ring resonator and a sidewall of the third waveguide.
18. The sensor of claim 17 , wherein the third waveguide is composed of crystalline silicon.
19. The sensor of claim 17 , wherein, when the flexible support element is unbent, the first gap has a width greater than 1 nm and less than 50 nm.
20. The sensor of claim 17 , wherein the second gap is between a sidewall of the second waveguide and the sidewall of the third waveguide.
21. The sensor of claim 17 , wherein the second gap is between a sidewall of the first waveguide and the sidewall of the third waveguide.