Systems and methods for tuning a cavity

• US 8,849,075 B2
• Filed: 11/09/2012
• Issued: 09/30/2014
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Painter, Oskar, Winger, Martin, Lin, Qiang, Safavi-Naeini, Amir, Alegre, Thiago, Blasius, Timothy Dobson, Krause, Alexander Grey
• Primary Examiner(s): Kim, Ellen
• Application Number:
  US13/673,916
• Publication Number:
  US 20130121633A1
• Time in Patent Office: 690 Days
• Field of Search: 385/14, 385/4, 385/40, 385/129, 385/9, 385/8, 385/16
• US Class Current: 385/14
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices

Abstract

The present disclosure describes an integrated opto-mechanical and electro-mechanical system. The opto-mechanical and electro-mechanical system can be made of photonic crystals configured to move based on electrical voltages and/or back action effects from electromagnetic waves, thus changing the resonance of the system.

Claims

1. A system comprising:

a first photonic crystal (PC) having a first inner edge and a first outer edge, the first PC comprising a first plurality of holes;

a second PC having a second inner edge and a second outer edge, the second PC comprising a second plurality of holes, the second inner edge of the second PC being adjacent to the first inner edge of the first PC;

at least one of a waveguide section and a wave trap section formed between the first PC and the second PC, wherein the wave trap section is configured to trap an electromagnetic wave within a cavity; and

a first pair of capacitively coupled metal contacts located outside an optical mode volume, the first pair of capacitively coupled metal contacts comprising a first metal contact and a second metal contact, the second metal contact contacting the first outer edge of the first PC,

wherein a first electrical voltage is adapted to be applied across the first pair of metal contacts, and

wherein the first PC is adapted to move as a function of at least one of the first electrical voltage and the electromagnetic wave such that the at least one of the waveguide section and the wave trap section contracts or expands.

2. The system of claim 1, wherein the first plurality of holes and the second plurality of holes are arranged in a periodic array.

3. The system of claim 2, wherein a lattice constant of the periodic array is varied throughout the first PC and the second PC, the varied lattice constant configuring the waveguide section and the wave trap section.

4. The system of claim 3, wherein a size of the first plurality of holes and the second plurality of holes, a shape of the first plurality of holes and the second plurality of holes, and/or separation between the first plurality of holes and the second plurality of holes of the periodic array is varied to change electromagnetic wave propagation properties of the system.

5. The system of claim 4, wherein the size of each hole of the first plurality of holes and the second plurality of holes is larger near the wave trap section along the first inner edge of the first PC and the second inner edge of the second PC.

6. The system of claim 4, wherein spacing between the first plurality of holes and the second plurality of holes is closer near the wave trap section along the first inner edge of the first PC and the second inner edge of the second PC.

7. The system of claim 1, wherein the wave trap section is a section between two waveguide sections, thus forming the cavity.

8. The system of claim 1, further comprising a second pair of capacitively coupled metal contacts located outside the optical mode volume, the second pair of contacts comprising a third metal contact and a fourth metal contact, the third metal contact contacting the second outer edge of the second PC, wherein a second electrical voltage is adapted to be applied across the second pair of metal contacts.

9. The system of claim 8, wherein the second PC is adapted to move as a function of at least one of the second electrical voltage and the electromagnetic wave such that the at least one of the waveguide section and the wave trap section contracts or expands.

10. The system of claim 1, wherein the second PC is fixed during movement of the first PC.

11. The system of claim 1, wherein a resonant frequency of the system is tuned as a function of an arrangement of the first plurality of holes in the first PC and the second plurality of holes in the second PC, wherein the electromagnetic wave is trapped in the wave trap section at the resonant frequency.

12. The system of claim 1, wherein the electromagnetic wave is a light wave or a microwave.

13. The system of claim 12, further comprising a laser light source to provide the light wave.

14. The system of claim 1, further comprising trenches to electrically isolate the first metal contact from the second metal contact, the trenches being formed through a semi-conductive silicon layer and into a non-conductive silicon dioxide layer, thus allowing high-bandwidth changes to the first electrical voltage.

15. The system of claim 8, further comprising trenches to electrically isolate the third metal contact from the fourth metal contact, the trenches being formed through a semi-conductive silicon layer and into a non-conductive silicon dioxide layer, thus allowing high-bandwidth changes to the second electrical voltage.

16. The system of claim 1, wherein a mass of the system is selected such that a back-action effect as a consequence of the electromagnetic wave is able to change intrinsic parameters of the system.

17. The system of claim 16, wherein the intrinsic parameters comprise temperature and resonance frequency of a mechanical mode.

18. The system of claim 1, wherein a separation distance between the first pair of capacitively coupled metal contacts and the optical mode volume allows for low-loss transmission or low-loss trapping of the electromagnetic wave.

19. The system of claim 8, wherein a separation distance between the second pair of capacitively coupled metal contacts and the optical mode volume allows for low-loss transmission or low-loss trapping of the electromagnetic wave.

24. The system of claim 1, wherein the cavity is a coupled microring cavity comprising a top ring and a bottom ring.

25. The system of claim 24, wherein the microring cavity is tapered such that there is a thickness difference between the top ring and the bottom ring.

20. A method comprising:

propagating an electromagnetic wave through a waveguide section formed between a first photonic crystal (PC) and a second PC;

trapping the electromagnetic wave within a wave trap section formed between the first PC and the second PC, thereby causing the waveguide and the wave trap section to contract or expand; and

applying a first electrical voltage across a first pair of capacitively coupled metal contacts, the first pair of capacitively coupled metal contacts comprising a first metal contact and a second metal contact, wherein the application of the first electrical voltage causes the waveguide section and the wave trap section between the first PC and the second PC to expand or contract.

21. The method of claim 20, further comprising applying a second electrical voltage across a second pair of capacitively coupled metal contacts, the second pair of capacitively coupled metal contacts comprising a third metal contact and a fourth metal contact, wherein the application of the second electrical voltage causes a cavity between the first PC and the second PC to expand or contract.

22. A method to change an optical resonance frequency, the method comprising:

applying an electrical voltage across a first pair of capacitively coupled metal contacts comprising a first metal contact and a second metal contact, the second metal contact contacting a first outer edge of a first photonic crystal (PC);

changing position of the first PC as a function of the applied electrical voltage across the first pair of metal contacts, thus causing a waveguide section and a wave trap section between the first PC and the second PC to expand or contract; and

shining light to the waveguide section and the wave trap section.

23. The method of claim 22, further comprising applying an electrical voltage across a second pair of capacitively coupled metal contacts comprising a third metal contact and a fourth metal contact, the fourth metal contact contacting a second outer edge of a second PC.

26. An apparatus comprising:

a first photonic crystal (PC) comprising a first periodic array of holes;

a second PC comprising a second periodic array of holes;

a slot between the first PC and the second PC, wherein the slot includes at least one of a waveguide section configured to guide an electromagnetic wave and a wave trap section configured to confine the electromagnetic wave within a cavity;

one or more pairs of capacitively coupled metal contacts bounding the first PC and the second PC configured to electromechanically control a motion of the first PC and the second PC and a width of the slot such that the at least one of the waveguide section and the wave trap section contracts or expands; and

one or more trenches etched between the capacitively coupled metal contacts of the one or more pairs, the trenches configured to electrically isolate the capacitively coupled metal contacts of each pair.

27. The apparatus of claim 26, wherein the first PC, the second PC, and the slot formed between the first and second PC are suspended on one or more struts.

28. The apparatus of claim 27, wherein an optical field is localized on the one or more struts.

29. The apparatus of claim 26, wherein the cavity is a coupled microring cavity comprising a top ring and a bottom ring that is tapered such that there is a thickness difference between the top ring and the bottom ring.

30. The apparatus of claim 26, wherein the apparatus is integrated with a silicon chip.