# US 12,001,115 B2 · Optical modulator and method of use

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- Number: US 12,001,115 B2
- Document ID: US12001115B2
- Status: Granted
- Kind: B2
- Application number: 17/712,036
- Filed: 2022-04-01
- Published: 2022-07-21
- Granted: 2024-06-04
- Earliest claimed: 2017-03-17
- Assignees: Rockley Phonics Limited; California Institute of Technology
- Applicants: Rockley Photonics Limited; California Institute of Technology
- Inventors: Arian Hashemi Talkhooncheh; Azita Emami; Yi Zhang; Aaron Zilkie
- Web page: https://patentgrep.com/patent/US12001115B2

## CPC

- G02F 1/212: {Mach-Zehnder type}
- G02F 1/225: in an optical waveguide structure
- H04B 10/5053: {using a parallel, i.e. shunt, combination of modulators}
- H04B 10/524: Pulse modulation
- H04B 10/541: {Digital intensity or amplitude modulation}
- G02F 1/0121: {Operation of devices; Circuit arrangements, not otherwise provided for in this subclass}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H04B: TRANSMISSION

## Abstract

An optical device. In some embodiments, the device comprises: an input waveguide, configured to receive light; a first electro-absorption modulator, coupled to receive light from the input waveguide, and operable to produce a first output or a second output, wherein the second output has a lower amplitude than the first output; a second electro-absorption modulator, coupled to receive light from the input waveguide, and operable to produce a third output or a fourth output, wherein the fourth output has a lower amplitude than the third output; and an output waveguide, coupled to receive light from the first electro-absorption modulator and the second electro-absorption modulator, and output a combined signal comprising an output of the first electro-absorption modulator and an output of the second electro-absorption modulator.

## Claims

### Claim 1

An optoelectronic device for modulation,
comprising:
an input waveguide;
a first intermediate waveguide and a second intermediate waveguide, each coupled to the input waveguide via an input coupler; and
an output waveguide, coupled, via an output coupler, to the first intermediate waveguide and to the second intermediate waveguide,
wherein:
the first intermediate waveguide includes a first modulating component connected in series with a first phase shifting component; and
the second intermediate waveguide includes a second modulating component connected in series with a second phase shifting component,
wherein:
the input coupler is a variable input coupler; or
the output coupler is a variable output coupler,
wherein the input coupler comprises a first Mach-Zehnder interferometer,
wherein the first Mach-Zehnder interferometer comprises a multimode interference (MMI) coupler,
wherein the optoelectronic device comprises a second Mach-Zehnder interferometer, the second Mach-Zehnder interferometer including:
as a variable input coupler of the second Mach-Zehnder interferometer, the first Mach-Zehnder interferometer;
as a first arm of the second Mach-Zehnder interferometer, the first intermediate waveguide;
as a second arm of the second Mach-Zehnder interferometer, the second intermediate waveguide; and
as a variable output coupler of the second Mach-Zehnder interferometer, a third Mach-Zehnder interferometer, and
wherein the third Mach-Zehnder interferometer comprises, as an output coupler of the third Mach-Zehnder interferometer, a 2×2 multimode interference coupler having an unequal coupling ratio.

### Claim 2 (depends on 1)

The optoelectronic device of claim 1, wherein the coupling ratio is between 0.1% and 10.0%.

### Claim 3 (depends on 1)

A method, comprising:
receiving light, in the input waveguide, and
applying a modulation to the received light, with the optoelectronic device of claim 1.

### Claim 4 (depends on 3)

The method of claim 3, wherein the coupling ratio is between 0.1% and 10.0%.

### Claim 5 (depends on 3)

The method of claim 3, further comprising:
a first heater on the first intermediate waveguide; and
a second heater on the second intermediate waveguide.

### Claim 6 (depends on 5)

The method of claim 5, wherein a heating coefficient of the first heater for the first modulating component is at least 0.01 of a heating coefficient of the first heater for the first phase shifting component.

### Claim 7 (depends on 6)

The method of claim 6, further comprising:
maintaining a relative phase in the first arm and in the second arm, at a first operating point,
maintaining a wavelength of maximum normalized extinction ratio for the first modulating component at a second operating point, and
maintaining a wavelength of maximum normalized extinction ratio for the second modulating component at a third operating point.

### Claim 8

An optoelectronic device for modulation, comprising:
an input waveguide;
a first intermediate waveguide and a second intermediate waveguide, each coupled to the input waveguide via an input coupler;
an output waveguide, coupled, via an output coupler, to the first intermediate waveguide and to the second intermediate waveguide;
a first heater on the first intermediate waveguide; and
a second heater on the second intermediate waveguide,
wherein:
the first intermediate waveguide includes a first modulating component connected in series with a first phase shifting component; and
the second intermediate waveguide includes a second modulating component connected in series with a second phase shifting component,
wherein:
the input coupler is a variable input coupler; or
the output coupler is a variable output coupler,
wherein the input coupler comprises a first Mach-Zehnder interferometer,
wherein the first Mach-Zehnder interferometer comprises a multimode interference (MMI) coupler, and
wherein the optoelectronic device comprises a second Mach-Zehnder interferometer, the second Mach-Zehnder interferometer including:
as a variable input coupler of the second Mach-Zehnder interferometer, the first Mach-Zehnder interferometer;
as a first arm of the second Mach-Zehnder interferometer, the first intermediate waveguide;
as a second arm of the second Mach-Zehnder interferometer, the second intermediate waveguide; and
as a variable output coupler of the second Mach-Zehnder interferometer, a third Mach-Zehnder interferometer.

### Claim 9 (depends on 8)

The optoelectronic device of claim 8, wherein a heating coefficient of the first heater for the first modulating component is at least 0.01 of a heating coefficient of the first heater for the first phase shifting component.

### Claim 10

A system, comprising an optoelectronic device for modulation and a control circuit, wherein the optoelectronic device comprises:
an input waveguide;
a first intermediate waveguide and a second intermediate waveguide, each coupled to the input waveguide via an input coupler; and
an output waveguide, coupled, via an output coupler, to the first intermediate waveguide and to the second intermediate waveguide,
wherein:
the first intermediate waveguide includes a first modulating component connected in series with a first phase shifting component; and
the second intermediate waveguide includes a second modulating component connected in series with a second phase shifting component,
wherein:
the input coupler is a variable input coupler; or
the output coupler is a variable output coupler,
wherein the input coupler comprises a first Mach-Zehnder interferometer,
wherein the first Mach-Zehnder interferometer comprises a multimode interference (MMI) coupler,
wherein the optoelectronic device comprises a second Mach-Zehnder interferometer, the second Mach-Zehnder interferometer including:
as a variable input coupler of the second Mach-Zehnder interferometer, the first Mach-Zehnder interferometer;
as a first arm of the second Mach-Zehnder interferometer, the first intermediate waveguide;
as a second arm of the second Mach-Zehnder interferometer, the second intermediate waveguide; and
as a variable output coupler of the second Mach-Zehnder interferometer, a third Mach-Zehnder interferometer, and
wherein the control circuit is configured to control a plurality of heaters, to:
maintain a relative phase in the first arm and in the second arm, at a first operating point,
maintain a wavelength of maximum normalized extinction ratio for the first modulating component at a second operating point, and
maintain a wavelength of maximum normalized extinction ratio for the second modulating component at a third operating point.