Photonic band structure devices

• US 20050094956A1
• Filed: 11/04/2003
• Published: 05/05/2005
• Est. Priority Date: 11/04/2003
• Status: Active Grant

• Current Assignee: Quantum NIL Limited, Quantum NIL Limited Taiwan Branch
• Original Assignee: Mesophotonics Limited
• Inventors: Zoorob, Majd, Parker, Greg, Charlton, Martin, Cox, Simon James
• Granted Patent: US 7,248,770 B2
• Time in Patent Office: Days
• US Class Current: 385/129
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices

Abstract

The invention provides a photonic structure comprising a first region (3) formed from a material having a first refractive index; and an array of sub-regions (5) formed in the first region, each sub-region having a refractive index different to the first refractive index;

• • wherein the array of sub-regions (5) can be defined by a plurality of rows and columns, wherein the position of each sub-region relative to adjacent sub-regions in each row and the properties of the sub-regions across each row are defined by parameters of a first type, and the position of each row relative to adjacent rows, and the properties of the sub-regions along each column are defined by parameters of a second type; and wherein at least one parameter of a first type and at least one parameter of the second type is varied systematically and independently across the array. The present invention gives rise to structures with photonic band structures that can be tailored to a particular application. A variation in the first type of parameter has a different effect to a variation in the second type of parameter. Variation in a first type of parameter alters the diffracting properties of each row in the stack of rows. Variation in a second type of parameter affects the reflective properties of the structure. According to another aspect of the invention, a method for manufacturing photonic structures is provided including a computer optimisation process in the design stage.

Claims

1. A photonic structure comprising:

a first region formed from a material having a first refractive index; and

an array of sub-regions formed in the first region, each sub-region having a refractive index different to the first refractive index;

wherein the array of sub-regions forms a plurality of rows and columns,

wherein the position of each sub-region relative to adjacent sub-regions in each row and the properties of the sub-regions across each row relative to adjacent rows are defined by parameters of a first type, and the position of each row relative to adjacent rows, and the properties of the sub-regions along each column are defined by parameters of a second type; and

wherein at least one parameter of a first type and at least one parameter of the second type varies systematically across the array, the at least one parameter of a first type varying independently of the at least one parameter of a second type.

2. A photonic structure according to claim 1, wherein at least one parameter is varied discontinuously across the array.

3. A photonic structure according to claim 1, wherein the properties of the sub-regions include size, shape and refractive index.

4. A photonic structure according to claim 1, wherein the positions of sub-regions relative to adjacent sub-regions or the properties of the sub-regions are varied systematically across at least one row.

5. A photonic structure according to claim 1, wherein the photonic structure is part of a planar waveguide structure.

6. A photonic structure according to claim 5, wherein the planar waveguide structure comprises a core layer and a cladding layer, and wherein the array of sub-regions is formed in the core layer or the cladding layer or in both.

7. A photonic structure according to claim 1, wherein the sub-regions each have a refractive index higher than the first refractive index.

8. An optical device comprising:

an optical input;

a photonic structure coupled to the optical input; and

an optical output coupled to the photonic structure;

wherein the photonic structure is a photonic structure according to any one of the preceding claims.

9. An optical device according to claim 8, wherein the optical input and optical output are coupled to the photonic structure so that the optical signals from the optical input propagate through the photonic structure in a direction perpendicular to the rows of sub-regions in order to reach the output.

10. An optical device according to claim 8, wherein the optical input is coupled to an input facet of the photonic structure and the optical output is coupled to an output facet of the photonic structure, and wherein the input facet and/or the output facet is oblique to the direction of propagation of optical signals passing from the optical input to the optical output.

11. A method of manufacturing a photonic structure comprising a first region formed from a material having a first refractive index, and an array of sub-regions formed in the first region, each sub-region having a refractive index different to the first refractive index, wherein the array of sub-regions is defined by a plurality of parameters;

comprising the steps of;

defining objective properties of a photonic band structure to be achieved;

modelling a basic photonic structure including an array of sub-regions on a computer and determining its photonic band structure;

selecting two or more parameters defining the array;

systematically varying the selected parameters across the array to provide a new photonic structure;

determining the photonic band structure of the new photonic structure;

comparing the photonic band structure of the new photonic structure with the objective properties defined in step (a), and assigning a figure of merit to the new photonic structure based on the comparison;

repeating steps (d) to (f) a plurality of times to obtain a figure of merit for a plurality of photonic structures; and

selecting a photonic structure from the plurality of photonic structures based on the figure of merit data of step (g); and

fabricating the selected photonic structure.

12. A method according to claim 11, further comprising the steps of:

having selected a photonic structure in step (h), selecting at least one further parameter defining the array; and

systematically varying the further parameter across the array to tune a photonic band structure of the photonic structure.

13. A method according to claim 11, wherein the array of sub-regions form a plurality of rows and columns;

wherein the position of each sub-region relative to adjacent sub-regions in each row and the properties of the sub-regions across each row are defined by parameters of a first type;

the position of each row relative to adjacent rows and the properties of the sub-regions along each column are defined by parameters of a second type; and

wherein the parameters selected in step (c) comprise at least one parameter of the first type and at least one parameter of the second type.

14. A method according to claim 11, wherein the basic photonic structure has a square or triangular lattice of sub-regions.