Optical free-space communication

Patent metadata

Field	Value
Publication number	US-11616572-B2
Application number	US-202117529957-A
Country	US
Kind code	B2
Filing date	Nov 18, 2021
Priority date	Nov 19, 2020
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

Transmitting at least two optical signals to at least two receivers, using a source, an alignment module, and a telescope. The telescope has a field of view in which the at least two receivers are located, and at least a first beam path and a second beam path are aligned in the alignment module in order to respectively steer the first optical signal via the telescope to the first receiver and the second optical signal via the telescope to the second receiver.

First claim

The invention claimed is:

1. A method for the transmission of at least two optical signals to at least two receivers, using elements comprising a source, an alignment module, and one telescope, the at least two receivers comprising a first receiver and a second receiver,
generating, by the source, two or more optical signals, at least a first optical signal and a second optical signal, and
guiding the first optical signal on a first beam path from the source via the alignment module and the one telescope to the first receiver, and guiding the second optical signal on a second beam path from the source via the alignment module and the one telescope to the second receiver,
wherein
the one telescope has a field of view in which the at least first and second receivers are located,
at least one of the first beam path or the second beam path is aligned in the alignment module in order to steer the first optical signal via the one telescope to the first receiver and in order to steer the second optical signal via the one telescope to the second receiver, and
the telescope optics is optimized in order to compensate optical errors for at least one of the first optical signal or the second optical signal, in order to compensate optical errors for optical signals sent on beam paths outside the optical axis of the telescope, the optimization forming optimized sub-areas in which the receivers are located.

2. The method according to claim 1 ,
wherein
the alignment in the alignment module of at least one of the first beam path or the second beam path comprises at least one of
a shift of at least one of the first beam path or the second beam path, the shift being at least one of parallel to the optical axes of the telescope or off axes to the optical axes of the telescope, or
a tilt of at least one of the first beam path or the second beam path by angle of incidence >0 to the optical axes of the telescope.

3. The method according to claim 2 ,
wherein at least one of
the shift is a distance x out of the optical axes of the telescope in the entrance plane of the telescope, or
the tilt is an angle α>0 to the optical axes of the telescope in the entrance plane of the telescope.

4. The method according to claim 2 ,
wherein
the at least first beam path is at least one of shifted by a distance x 1 or tilted by an angle α 1 , and the at least second beam path is at least one of shifted by a distance x 2 or tilted by an angle α 2 , and at least one of x 1 ≠x 1 , or α 1 ≠α 2 .

5. The method according to claim 1 ,
wherein at least one of
the alignment enables a tracking of at least one of the first receiver or the second receiver while the source, and the alignment module, and the telescope or at least one of the first receiver or the second receiver are moving to each other, or
the alignment enables a switching of at least one or the first optical signal or the second optical signal between a multitude of receivers.

6. The method according to claim 1 ,
wherein
the optical signal is a quantum signal, or a quantum state of light, or a single photon state, or a faint laser pulse, or a single photon, or an entangled photon state, or an entangled photon of an entangled photon pair or an entangled three- or more-photon state.

7. The method according to claim 1 ,
wherein
the at least first beam of the first optical signal is focused on the first receiver, and the at least second beam of the second optical signal is focused on the second receiver.

8. The method according to claim 1 ,
wherein
in the at least first beam with the first beam diameter the first receiver is located, and in the at least second beam with the second beam diameter the second receiver is located, the at least first receiver is located outside the second beam with the second beam diameter, and the at least second receiver is located outside the first beam with the first beam diameter.

9. The method according to claim 1 ,
wherein
the at least first and second optical signals are used for optical communication or quantum key distribution.

10. The method according to claim 1 ,
wherein
the alignment module comprises at least one of a first alignment means for the first optical signal, in order to align the first optical signal, or
a second alignment means for the second optical signal, in order to align the second optical signal.

11. The method according to claim 1 ,
wherein
the at least one of the first receiver or the second receiver is located outside of the extended optical axis of the telescope.

12. A system for the transmission of at least two optical signals to at least two receivers, comprising a source, an alignment module, and one telescope, the at least two receivers comprising a first receiver and a second receiver,
wherein in the source the at least two optical signals are generated, at least a first and a second optical signal, whereas the first optical signal is guided on a first beam path from the source via the alignment module and the one telescope to the first receiver and the second optical signal is guided on a second beam path from the source via the alignment module and the one telescope to the second receiver,
wherein
the system comprises a single telescope, whereas the one telescope has a field of view in which the at least first and second receivers are located, and
the alignment module comprises at least one of a first alignment means and a second alignment means, for the at least one of the first optical signal and the second optical signal, in order to steer the at least first optical signal via the one telescope to the first receiver and the second optical signal via the one telescope to the second receiver,
the telescope optics is optimized in order to compensate optical errors for at least one of the first optical signal or the second optical signal, in order to compensate optical errors for optical signals sent on beam paths outside the optical axis of the telescope, the optimization forming optimized sub-areas in which the receivers are located, and
the at least two receivers comprise at least one of a detection means or a redirection means, to respectively detect or redirect the at least first and second optical signals.

13. The system according to claim 12 ,
wherein
the at least one of the first alignment means or second alignment means comprises at least one of a fiber with a shiftable fiber output, a fiber with a tiltable fiber output, a tiltable beam steering mirror, a deformable mirror, a spatial light modulator, a shiftable lens or lens system, a tiltable lens or lens system, a shiftable prism or prism system, or a tiltable prism or prism system.

14. The system according to claim 12 ,
further comprising a tracking system in order to track the at least one of a first signal or second signal to the at least one of a first receiver or second receiver.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Steinlechner Fabian
• Berlich René

Classifications

• H04L9/0852

  Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03) · CPC title

• H04B10/70 Primary

  Photonic quantum communication · CPC title

• G02B27/30

  Collimators · CPC title

• H04B10/112 Primary

  Line-of-sight transmission over an extended range · CPC title

• H04B10/60

  Receivers · CPC title