Optical methods and devices

Patent metadata

Field	Value
Publication number	US-11650617-B2
Application number	US-201816764893-A
Country	US
Kind code	B2
Filing date	Jun 28, 2018
Priority date	Nov 21, 2017
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

A method of performing a multiplication operation in the optical domain using a device (100) comprising: an optical waveguide (101), and a modulating element (102) that is optically coupled to the optical waveguide (101), the modulating element (102) modifying a transmission, reflection or absorption characteristic of the waveguide (101) dependant on its state, wherein the state of the modulating element (102) is adjustable by a write signal (103). The method comprises: encoding a first value to the write signal (103), using the write signal (103) to map the first value to a state of the modulating element (102); encoding a second value to a read signal (104); producing an output signal intensity as the transmitted or reflected read signal, wherein the product of the first value and the second value is encoded in the output signal intensity.

First claim

The invention claimed is:

1. A method of performing a multiplication operation in the optical domain using a device comprising:
an optical waveguide, and a modulating element that is optically coupled to the optical waveguide, the modulating element modifying a transmission, reflection or absorption characteristic of the waveguide dependant on its state, wherein the state of the modulating element is adjustable by a write signal;
wherein the method comprises the following steps:
encoding a first value to the write signal,
using the write signal to map the first value to a state of the modulating element;
encoding a second value to a read signal;
producing an output signal intensity as the transmitted or reflected read signal, wherein the product of the first value and the second value is encoded in the output signal intensity; and
applying a transmission offset correction to the output signal intensity by subtracting a transmission baseline from the output signal intensity.

2. The method of claim 1 , wherein the modulating element is optically near-field coupled to the optical waveguide.

3. The method of claim 1 , wherein determining the result comprises applying a scaling correction to the output intensity, and/or wherein the first value and the second value have at least three different possible levels.

4. The method of claim 1 , wherein the modulating element comprises a phase change material.

5. The method of claim 4 , wherein the write signal maps the value of the write signal to a degree of amorphization of the modulating element, and/or wherein the modulating element is placed in a baseline crystalline condition prior to using the write signal.

6. The method of claim 1 , wherein there is a linear scaling between the first value and the product and between the second value and the product, and/or wherein the output pulse intensity is detected as the proportion of the read pulse that is transmitted, and/or wherein the read signal is an optical read pulse.

7. The method of claim 1 , comprising determining a vector or matrix multiplication by performing more than one multiplication operation, wherein the output signal is produced by combining transmitted and/or reflected signals from more than one waveguide, and/or
comprising using a device comprising more than one waveguide, each of the more than one waveguide comprising a corresponding modulating element, and/or
wherein the device further comprises at least one optical combiner, each combiner configured to combine the output signal produced by more than one waveguide, and/or
wherein the optical waveguide is a first optical waveguide, and the device further comprises a second waveguide, transverse to the first waveguide in the region of the modulating element, wherein the modulating element is optically coupled to both the first waveguide and the second waveguide.

8. The method of claim 1 , wherein the state of the modulating element is adjustable by an optical signal carried by the waveguide and the step of using the write signal to map the first value to a state of the modulating element comprises transmitting the write signal through the waveguide.

9. The method of claim 8 , wherein the write signal is an optical write pulse.

10. The method of claim 1 , wherein the write signal is an electrical signal.

11. The method of claim 10 , wherein the waveguide is doped and the electrical signal is applied to the doped waveguide, or
wherein the electrical signal is applied to a resistive element proximate the modulating element.

12. The method according to claim 10 , wherein the electrical signal is an electrical current pulse.

13. A method of performing a multiplication operation in the optical domain using a device comprising:
an optical waveguide, and a modulating element that is optically coupled to the optical waveguide, the modulating element modifying a transmission, reflection or absorption characteristic of the waveguide dependant on its state, wherein the state of the modulating element is adjustable by a write signal;
wherein the method comprises the following steps:
encoding a first value to the write signal,
using the write signal to map the first value to a state of the modulating element;
encoding a second value to a read signal;
producing an output signal intensity as the transmitted or reflected read signal, wherein the product of the first value and the second value is encoded in the output signal intensity;
wherein the state of the modulating element is adjustable by an optical signal carried by the waveguide and the step of using the write signal to map the first value to a state of the modulating element comprises transmitting the write signal through the waveguide; and
wherein the modulating element is placed in a baseline crystalline condition prior to using the write signal, and wherein placing the modulating element in a baseline crystalline condition comprises using a two-step reset pulse, the first step having a higher power and shorter duration than the second step, and with less than 5 ns delay between the first step and second step.

14. A method of performing a multiplication operation in the optical domain using a device comprising:
an optical waveguide, and a modulating element that is optically coupled to the optical waveguide, the modulating element modifying a transmission, reflection or absorption characteristic of the waveguide dependant on its state, wherein the state of the modulating element is adjustable by a write signal;
wherein the method comprises the following steps:
encoding a first value to the write signal,
using the write signal to map the first value to a state of the modulating element;
encoding a second value to a read signal;
producing an output signal intensity as the transmitted or reflected read signal, wherein the product of the first value and the second value is encoded in the output signal intensity;
wherein the state of the modulating element is adjustable by an optical signal carried by the waveguide and the step of using the write signal to map the first value to a state of the modulating element comprises transmitting the write signal through the waveguide; and
wherein the write signal is a first write signal that maps the first value to a state of a first region of the modulating element, and the method further comprises:
encoding a third value to a second write signal, and using the second write signal to map the third value to a state of a second region of the modulating element, wherein the output signal intensity encodes the product of the first, second and third values and/or the sum of the first value multiplied by the second value and the first value multiplied by the third value.

15. The method of claim 14 , wherein the first and second write signal are propagated in different directions, and/or
wherein the device comprises a first waveguide defining a read signal propagation direction, and at least one further waveguide for carrying write signals in a different direction to the direction of read signal propagation.

16. A method of performing a multiplication operation in the optical domain using a device comprising:
an optical waveguide, and a modulating element that is optically coupled to the optical waveguide, the modulating element modifying a transmission, reflection or absorption characteristic of the waveguide dependant on its state, wherein the state of the modulating element is adjustable by a write signal;
wherein the method comprises the following steps:
encoding a first value to the write signal,
using the write signal to map

Assignees

• Univ Oxford Innovation Ltd

Inventors

• Rios Ocampo Carlos A
• Youngblood Nathan
• Cheng Zengguang
• Bhaskaran Harish

Classifications

• G02F1/0126

  Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass · CPC title

• G06E1/045 Primary

  Matrix or vector computation · CPC title

• G02F1/0147

  based on thermo-optic effects (G02F1/132 takes precedence) · CPC title

• G02F3/00

  Optical logic elements; Optical bistable devices · CPC title

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title