Laser writing for colour centres in crystals

Patent metadata

Field	Value
Publication number	US-11414783-B2
Application number	US-201917057226-A
Country	US
Kind code	B2
Filing date	May 17, 2019
Priority date	May 22, 2018
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

A method of fabricating one or more colour centres in a crystal is described. The method comprises focusing a laser into a crystal to induce the creation, modification, or diffusion of defects within a focal region of the laser. Fluorescence detection is used to determine when one or more colour centres are formed within the focal region and the laser is terminated when a desired number of colour centres have been formed. The method enables colour centres to be formed in a crystal with a high degree of control in terms of both the number and location of colour centres within the crystal, and a degree of control over other parameters such as colour centre orientation and local environment. In particular, it is possible to form a well-defined pattern of colour centres within a crystal.

First claim

The invention claimed is:

1. A crystal comprising:
a crystal lattice; and
a plurality of colour centres disposed within the crystal lattice,
wherein the colour centres are configured to map onto a pattern of points having defined locations, within the crystal lattice, and
wherein the colour centres have a maximum deviation from the defined locations of no more than 1 micrometre in a two-dimensional projection of the pattern of points,
and wherein a corresponding number of colour centres are disposed at least at 55% of the points of the pattern within the maximum deviation.

2. The crystal according to claim 1 ,
wherein the maximum deviation of the colour centres in the two-dimensional projection of the pattern of points is no more than one of: 750 nm; 500 nm; 300 nm; 200 nm; 150 nm; 100 nm; 80 nm; 50 nm; and 20 nm.

3. The crystal according to claim 1 ,
wherein the colour centres have a maximum deviation from the defined locations in a depth direction orthogonal to the two-dimensional projection of no more than one of: 4 micrometres; 2 micrometres; 1 micrometre; 750 nm; 500 nm; 300 nm; 200 nm; 150 nm; 100 nm; or 50 nm.

4. The crystal according to claim 1 ,
wherein the corresponding number of colour centres being disposed at least at 55% of the points of the pattern within the maximum deviation comprises only a single colour centre being disposed at least at one of: 55%, 60%, 70%, 80%, 90%, or 100% of the points of the pattern within the maximum deviation.

5. The crystal according to claim 1 ,
wherein the corresponding number of colour centres being disposed at least at 55% of the points of the pattern within the maximum deviation comprises the corresponding number of colour centres being disposed at least at one of: 55%, 60%, 70%, 80%, 90%, or 100% of the points of the pattern within the maximum deviation.

6. The crystal according to claim 1 ,
wherein the colour centres each comprise at least one atom coupled to at least one vacancy or at least two vacancies coupled together.

7. The crystal according to claim 1 ,
wherein the pattern forms a two dimensional or three dimensional array of regularly spaced colour centres or another non-random distribution of colour centres with a symmetric or mathematical relationship between the distribution of colour centres.

8. The crystal according to claim 1 ,
wherein the colour centres are preferentially oriented in one or more crystallographic directions of the crystal lattice.

9. The crystal according to claim 1 ,
further comprising one or more photonic structures to which one or more of the colour centres are coupled, wherein the coupled colour centres are located no more than 100 nm from the one or more photonic structures or located within the one or more photonic structures.

10. The crystal according to claim 1 ,
wherein the crystal comprises one or more surface projections and the colour centres are disposed in the one or more surface projections.

11. A method of fabricating one or more colour centres in a crystal, the method comprising:
focusing a first laser beam into a crystal to generate vacancy defects within a focal region of the first laser beam within the crystal lattice, the first laser beam having a first energy;
focusing a second laser beam onto the focal region to induce diffusion of the vacancy defects within the focal region, the second laser beam having a second energy which is lower than the first energy, wherein the second laser beam provides a stream of laser pulses of energy sufficiently high to induce vacancy diffusion within the focal region, but sufficiently low as to not form new vacancy defects;
detecting, via fluorescence, when a colour centre is formed within the focal region; and
terminating the laser when a desired number of colour centres have been formed.

12. The method according to claim 11 , wherein the laser is controlled to form an atom-vacancy defect by one of:
diffusion of a vacancy defect within the focal region;
laser-induced modification of an existing defect by dissociation of a vacancy; or generation of a Frenkel defect immediately adjacent to a substitutional impurity.

13. The method according to claim 11 , wherein the second laser beam provides sub-picosecond laser pulses.

14. The method according to claim 11 , wherein the laser beam has a cross-sectional beam profile with a full-width-half maximum of no more than at least one of: 500 nm, 400 nm, 350 nm, 200 nm, 250 nm, or 100 nm.

15. The method according to claim 11 , further comprising:
after detecting, via fluorescence, when a colour centre, or combination of colour centres, is formed within the focal region, making a determination from the fluorescence that the colour centre or combination of colour centres does not have a desired property or combination of properties; and
in response to making the determination, continuing laser processing until the colour centre or combination or colour centres is formed with the desired property or combination of properties.

16. The method according to claim 15 , further comprising:
prior to continuing laser processing until the colour centre or combination or colour centres is formed with the desired property or combination of properties, controling laser processing to dissociate the colour centre or combination of colour centres.

17. An apparatus for fabricating colour centres in a crystal, the apparatus comprising:
a laser system comprising a laser;
a fluorescence detector; and
an electronic controller coupled to the laser system and the fluorescence detector, wherein the controller is configured to:
focus a first laser beam into a crystal to generate vacancy defects within a focal region of the first laser beam within the crystal lattice, the first laser beam having a first energy;
focus a second laser beam onto the focal region to induce diffusion of the vacancy defects within the focal region, the second laser beam having a second energy which is lower than the first energy, wherein the second laser beam provides a stream of laser pulses of energy sufficiently high to induce vacancy diffusion within the focal region, but sufficiently low as to not form new vacancy defects;
use the fluorescence detector to detect, via fluorescence, when a colour centre is formed within the focal region; and
terminate the laser when a desired number of colour centres have been formed.

18. A crystal comprising one or more colour centres fabricated by operations comprising:
focusing a first laser beam into a crystal to generate vacancy defects within a focal region of the first laser beam within the crystal lattice, the first laser beam having a first energy;
focusing a second laser beam onto the focal region to induce diffusion of the vacancy defects within the focal region, the second laser beam having a second energy which is lower than the first energy, wherein the second laser beam provides a stream of laser pulses of energy sufficiently high to induce vacancy diffusion within the focal region, but sufficiently low as to not form new vacancy defects;
detecting, via fluorescence, when a colour centre is formed within the focal region; and
terminating the laser when a desired number of colour centres have been formed.

19. A crystal according to claim 18 , the crystal comprising:
a crystal lattice; and
a plurality of colour centres disposed within the crystal lattice,
wherein the colour centres are configured to map onto a pattern of points having defined locations, within the crystal lattice, and
wherein the colour c

Assignees

• Univ Oxford Innovation Ltd

Inventors

• Smith Jason
• Booth Martin
• Salter Patrick
• Chen Yu Chen

Classifications

• C30B29/04 Primary

  Diamond · CPC title

• G01N21/6402

  Atomic fluorescence; Laser induced fluorescence · CPC title

• C01B32/28

  After-treatment, e.g. purification, irradiation, separation or recovery · CPC title

• C30B33/00 Primary

  After-treatment of single crystals or homogeneous polycrystalline material with defined structure (C30B31/00 takes precedence) · CPC title