One-dimensional photonic crystal with pillars having a layer structure

Patent metadata

Field	Value
Publication number	US-9715158-B1
Application number	US-201615087100-A
Country	US
Kind code	B1
Filing date	Mar 31, 2016
Priority date	Mar 31, 2016
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

The present invention is notably directed to a (quasi) one-dimensional photonic crystal cavity. This cavity comprises a set of aligned pillars, where the pillars are embedded in a cladding. At least one of the pillars has a sandwich structure, wherein a layer of nonlinear optical material is between two layers of materials having, each, a refractive index that is higher than the refractive index of the nonlinear optical material. The invention can furthermore be embodied as an all-optical modulator or an all-optical transistor, comprising a photonic crystal such as described above. Finally, the invention is further directed to methods for modulating an optical signal, using such a photonic crystal cavity.

First claim

What is claimed is:

1. A one-dimensional photonic crystal optical cavity comprising:
a set of aligned pillars, the pillars embedded in a cladding,

wherein,
at least one of the pillars of the set has a sandwich structure, wherein a layer of nonlinear optical material is between two layers of materials having, each, a refractive index that is higher than the refractive index of the nonlinear optical material.

2. A photonic crystal cavity according to claim 1 , wherein the set of pillars comprises:
two or more of the pillars of the set of pillars having, each, a sandwich structure as said at least one of the pillars.

3. A photonic crystal cavity according to claim 2 , wherein
each of the pillars of the set has a sandwich structure as said at least one of the pillars.

4. A photonic crystal cavity according to claim 1 , wherein the cavity further comprises:
pillars on each side of said set of pillars and aligned therewith, that are designed so as for a cavity frequency of said cavity to be within a photonic frequency bandgap of said cavity.

5. A photonic crystal cavity according to claim 4 , wherein
the cavity comprises a defect formed by a subset of said set of pillars, the defect designed so as to cause an optical mode within said photonic frequency bandgap.

6. A photonic crystal cavity according to claim 5 , wherein
pillars of said subset are dimensioned and/or spaced from each other so to as to create said defect.

7. A photonic crystal cavity according to claim 6 , wherein
one or more pillars of said subset are designed so as to encompass one or more nodes of zero electric field of a cavity mode.

8. A photonic crystal cavity according to claim 7 , wherein the set of pillars comprises:
two tapered subsets of pillars on each side of said defect, wherein each of the two subsets of pillars is tapered both in dimensions of and gaps between pillars of said each of the two subsets, so as to match a Bloch mode index of a mirror portion of the photonic crystal cavity to an effective refractive index of the defect.

9. A photonic crystal cavity according to claim 1 , wherein:
said nonlinear optical material comprises one or more of the following materials: BaTiO 3 , Ba x Sr y TiO 3 , KNbO 3 , LiNbO 3 , LiIO 3 , AlN, GaN, GaP, InP, GaAs, ZnO, CdTe, Sr x Ba 1-x Nb 2 O 6 , PbZr 0.52 Ti 0.48 O 3 , and LaTaO 3 .

10. A photonic crystal cavity according to claim 1 , wherein:
said nonlinear optical material comprises a phase change material, or PCM, having at least two reversibly switchable states, in which the PCM exhibits two different values of refractive index, said states being optically switchable; and
said two layers of materials have, each, a refractive index that is higher than at least one of said two different values of refractive index.

11. A photonic crystal cavity according to claim 1 , wherein
said nonlinear optical material comprises a photorefractive material.

12. A photonic crystal cavity according to claim 1 , wherein
said cladding comprises one or more of: SiO 2 ; SiO x N y ; Al 2 O 3 ; and an organic polymer.

13. A photonic crystal cavity according to claim 1 , wherein
said two layers of materials comprise, each, one or more of any of the following: Si; Ge; GaAs; InAlGaAs, InP; GaP; GaN; and AlN.

14. An all-optical modulator, comprising the photonic crystal cavity according to claim 1 .

15. An all-optical transistor, comprising the photonic crystal cavity according to claim 1 .

16. A method for modulating an optical signal comprising using a one-dimensional photonic crystal cavity comprising:
a set of aligned pillars, the pillars embedded in a cladding,

wherein,
at least one of the pillars of the set has a sandwich structure, wherein a layer of nonlinear optical material is between two layers of materials having, each, a refractive index that is higher than the refractive index of the nonlinear optical material.

17. A method according to claim 16 , wherein the method further comprises:
irradiating the photonic crystal cavity with an optical control signal to modulate an optical signal propagated through said photonic crystal cavity.

18. A method according to claim 17 , wherein
irradiating comprises directing the control signal toward the photonic crystal cavity perpendicularly to an average plane of the layer of nonlinear optical material or in-plane with said average plane.

19. A method according to claim 16 , wherein
the method further comprises:
propagating an optical control signal in the photonic crystal cavity; and irradiating the photonic crystal cavity with said optical control signal, so as to modulate the latter.

20. A method according to claim 16 , wherein the method further comprises:
propagating both an optical control signal and an optical signal in the photonic crystal cavity, wherein the control signal has a first frequency, which matches a first optical mode of the photonic crystal cavity, and the optical signal has a second frequency, which matches a second optical mode of the photonic crystal cavity, the second optical mode having a lower quality factor than the first optical mode, so as to modulate said optical signal.

Assignees

• IBM

Inventors

• Abel Stefan
• Seidler Paul F

Classifications

• G02F1/3515 Primary

  All-optical modulation, gating, switching, e.g. control of a light beam by another light beam (G02F1/353, G02F1/37, G02F1/39 take precedence) · CPC title

• G02F2202/32

  Photonic crystals · CPC title

• G02F1/035

  in an optical waveguide structure · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• H01S5/105

  Electricity · mapped topic