Electromagnetic field detector

Patent metadata

Field	Value
Publication number	US-12449458-B2
Application number	US-202218548390-A
Country	US
Kind code	B2
Filing date	Feb 15, 2022
Priority date	Mar 1, 2021
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

This invention provides a method of detecting an electromagnetic field, and a device for 5 performing said method, the method comprising the steps of: transmitting a probe signal at a probe frequency in a first probe signal path and a second probe signal path to an optical receiver, wherein the first probe signal path passes through a transmission medium and the probe frequency is set to excite electrons of the transmission medium from a ground state to a first excited state; transmitting a coupling signal at a coupling frequency in a first coupling signal path, wherein the first coupling signal path overlaps with the first probe signal path in the transmission medium in a first overlapping section, wherein the coupling frequency is set to excite electrons of the transmission medium to a predetermined excited state so as to induce an Electromagnetic Induced Transparency, EIT, effect in the transmission medium such that an incident electromagnetic field at the transmission medium causes a change in refractive index in the transmission medium at the first overlapping section such that there is a change in an optical path length difference between the first probe signal path and the second probe signal path; combining the first path of the probe signal, following its passage of the first overlapping section of the transmission medium, with the second path of the probe signal; and monitoring, at the optical receiver, the intensity of the combined first and second paths of the probe signal so as to detect the incident electromagnetic field at the first overlapping section of the transmission medium as a change in the intensity caused by the change in the optical path length difference between the first probe signal path and the second probe signal path.

First claim

The invention claimed is:

1. A method of detecting an electromagnetic field, the method comprising:
transmitting a probe signal at a probe frequency in a first probe signal path and a second probe signal path to an optical receiver, wherein the first probe signal path passes through a transmission medium and the probe frequency is set to excite electrons of the transmission medium from a ground state to a first excited state;
transmitting a coupling signal at a coupling frequency in a first coupling signal path, wherein the first coupling signal path overlaps with the first probe signal path in the transmission medium in a first overlapping section, wherein the coupling frequency is set to excite electrons of the transmission medium to a predetermined excited state so as to induce an Electromagnetic Induced Transparency (EIT) effect in the transmission medium such that an incident electromagnetic field at the transmission medium causes a change in a refractive index in the transmission medium at the first overlapping section such that there is a change in an optical path length difference between the first probe signal path and the second probe signal path;
combining the first probe signal path, following the first probe signal path passing the first overlapping section of the transmission medium, with the second probe signal path; and
monitoring, at the optical receiver, an intensity of the combined first probe signal path and the second probe signal path so as to detect the incident electromagnetic field at the first overlapping section of the transmission medium as a change in the intensity caused by the change in the optical path length difference between the first probe signal path and the second probe signal path,
wherein the first probe signal path passes through the transmission medium in a plurality of passages, and the first coupling signal overlaps with the first probe signal path in the plurality of passages in a plurality of overlapping sections, and combining the first probe signal path with the second probe signal path is following passage by the first probe signal path of all overlapping sections of the plurality of overlapping sections.

2. The method as claimed in claim 1 , wherein monitoring the intensity of the combined first probe signal path and the second probe signal path includes demodulating information contained within the incident electromagnetic field.

3. The method as claimed in claim 2 , wherein the information is modulated based on frequency modulation and demodulating information contained within the incident electromagnetic field utilizes a value of transmission power for the incident electromagnetic field.

4. The method as claimed in claim 1 , wherein the electromagnetic field is a Radio Frequency (RF) field.

5. The method as claimed in claim 1 , wherein an interaction volume of any overlap of the coupling signal with the second probe signal path is different from an interaction volume of the first overlapping section.

6. The method as claimed in claim 5 , wherein the coupling signal does not overlap with the second probe signal path.

7. The method as claimed in claim 5 , wherein the coupling signal overlaps with the second probe signal path in a second overlapping portion such that the incident electromagnetic field causes a change in the refractive index in the transmission medium at the second overlapping portion, and an interaction volume of the second overlapping section is different from the interaction volume of the first overlapping section.

8. A method of detecting an electromagnetic field, the method comprising:
transmitting a probe signal at a probe frequency in a first probe signal path and a second probe signal path to an optical receiver, wherein the first probe signal path passes through a transmission medium and the probe frequency is set to excite electrons of the transmission medium from a ground state to a first excited state;
transmitting a coupling signal at a coupling frequency in a first coupling signal path, wherein the first coupling signal path overlaps with the first probe signal path in the transmission medium in a first overlapping section, wherein the coupling frequency is set to excite electrons of the transmission medium to a predetermined excited state so as to induce an Electromagnetic Induced Transparency (EIT) effect in the transmission medium such that an incident electromagnetic field at the transmission medium causes a change in a refractive index in the transmission medium at the first overlapping section such that there is a change in an optical path length difference between the first probe signal path and the second probe signal path;
combining the first probe signal path, following passage of the first probe signal of the first overlapping section of the transmission medium, with the second probe signal path; and
monitoring, at the optical receiver, an intensity of the combined first probe signal path and the second probe signal path so as to demodulate information contained within the incident electromagnetic field at the first overlapping section of the transmission medium as a change in the intensity caused by the change in the optical path length difference between the first probe signal path and the second probe signal path.

9. The method as claimed in claim 8 , wherein the information is modulated based on frequency modulation and demodulating information contained within the incident electromagnetic field utilizes a value of transmission power for the incident electromagnetic field.

10. The method as claimed in claim 8 , wherein the electromagnetic field is a Radio Frequency (RF) field.

11. The method as claimed in claim 8 , wherein an interaction volume of any overlap of the coupling signal with the second probe signal path is different to an interaction volume of the first overlapping section.

12. The method as claimed in claim 11 , wherein the coupling signal does not overlap with the second probe signal path.

13. The method as claimed in claim 11 , wherein the coupling signal overlaps with the second probe signal path in a second overlapping portion such that the incident electromagnetic field causes a change in the refractive index in the transmission medium at the second overlapping portion, and an interaction volume of the second overlapping section is different from an interaction volume of the first overlapping section.

14. A device for detecting an electromagnetic field, the device comprising:
a first optical transmitter;
a second optical transmitter;
a transmission medium;
an optical receiver; and
a processor:

wherein:
the first optical transmitter is configured to transmit a probe signal at a probe frequency in a first probe signal path and a second probe signal path to the optical receiver, wherein the first probe signal path passes through the transmission medium and the probe frequency is set to excite electrons of the transmission medium from a ground state to a first excited state,
the second optical transmitter is configured to transmit a coupling signal at a coupling frequency in a first coupling signal path, wherein the first coupling signal path overlaps with the first probe signal path in the transmission medium in a first overlapping section, wherein the coupling frequency is set to excite electrons of the transmission medium to a predetermined excited state so as to induce an Electromagnetic Induced Transparency (EIT) effect in the transmission medium such that an incident electromagnetic field at the transmission medium causes a change in a refractive index in the transmission medium at the first overlapping section suc

Assignees

• British Telecomm

Inventors

• Burton Fraser
• Menchetti Marco
• Bussey Liam

Classifications

• G01R29/0892

  Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value · CPC title

• G01R29/0885 Primary

  using optical probes, e.g. electro-optical, luminescent, glow discharge, or optical interferometers · CPC title