WFOV and NFOV shared aperture beacon laser

Patent metadata

Field	Value
Publication number	US-9755739-B1
Application number	US-201615171348-A
Country	US
Kind code	B1
Filing date	Jun 2, 2016
Priority date	Jun 2, 2016
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A method of free-space optical communication includes guiding, by focusing optics, an optical communication beam emitted from an optical transmitter into a double-clad optical fiber. The optical communication beam carrying data. The double-clad optical fiber has first and second ends, where the first end is arranged to receive the optical communication beam. The double-clad optical fiber includes a fiber core, a first cladding, and a second cladding. The method also includes directing, by collimating optics, the optical communication beam from the second end of the double-clad optical fiber toward an optical receiver of a communication terminal. the second portion of the optical communication beam arranged concentrically around the first portion of the optical communication beam, the first portion of the optical communication beam having a higher intensity than the second portion of the optical communication beam.

First claim

What is claimed is:

1. A method of free-space optical communication, the method comprising:
guiding, by focusing optics, an optical communication beam emitted from an optical transmitter into a double-clad optical fiber, the optical communication beam carrying data, the double-clad optical fiber having first and second ends, the first end arranged to receive the optical communication beam, the double-clad optical fiber comprising:
a fiber core having a first numerical aperture, the fiber core configured to propagate a first portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber;
a first cladding arranged concentrically around the fiber core, the first cladding having a second numerical aperture equal to or greater than the first numerical aperture, the first cladding configured to propagate a second portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber; and
a second cladding arranged concentrically around the first cladding; and

directing, by collimating optics, the optical communication beam from the second end of the double-clad optical fiber toward an optical receiver of a communication terminal, the second portion of the optical communication beam arranged concentrically around the first portion of the optical communication beam, the first portion of the optical communication beam having a higher intensity than the second portion of the optical communication beam,
wherein the focusing optics are configured to:
direct the first portion of the optical communication beam from the optical transmitter into the fiber core of the double-clad optical fiber; and
direct the second portion of the optical communication beam from the optical transmitter into the first cladding of the double-clad optical fiber.

2. The method of claim 1 , wherein the optical transmitter comprises a multi-mode light source.

3. A method of free-space optical communication, the method comprising:
guiding, by focusing optics, an optical communication beam emitted from an optical transmitter into a double-clad optical fiber, the optical communication beam carrying data, the double-clad optical fiber having first and second ends, the first end arranged to receive the optical communication beam, the double-clad optical fiber comprising:
a fiber core having a first numerical aperture, the fiber core configured to propagate a first portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber;
a first cladding arranged concentrically around the fiber core, the first cladding having a second numerical aperture equal to or greater than the first numerical aperture, the first cladding configured to propagate a second portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber; and
a second cladding arranged concentrically around the first cladding;

perturbing the fiber core to couple the second portion of the optical communication beam from the fiber core to propagate in a fiber grating as a low intensity portion of the optical communication beam, the first portion of the optical communication beam propagating in the fiber core as a high intensity portion of the optical communication beam; and
directing, by collimating optics, the optical communication beam from the second end of the double-clad optical fiber toward an optical receiver of a communication terminal, the second portion of the optical communication beam arranged concentrically around the first portion of the optical communication beam, the first portion of the optical communication beam having a higher intensity than the second portion of the optical communication beam.

4. The method of claim 3 , wherein the perturbation of the fiber core comprises exerting a diametric force on the double-clad optical fiber to cause a microbending loss of the fiber core, resulting in the coupling of the second portion of the optical communication beam from the fiber core to propagate in the fiber grating as the low intensity portion of the optical communication beam, a coupling ratio of the second portion of the optical communication beam to the first portion of the optical communication beam depending on a strength of the diametric force and at least one period of at least one corresponding groove formed in the double-clad optical fiber due to the diametric force.

5. The method of claim 3 , wherein the perturbation of the fiber core causes a speckle free, flat top type of output power profile of the optical communication beam as the optical communication beam exits the double-clad optical fiber.

6. The method of claim 3 , wherein the optical transmitter comprises a single-mode light source.

7. The method of claim 1 , further comprising coupling, by a long period grating, the second portion of the optical communication beam from the fiber core to propagate in the long period grating as a low intensity portion of the optical communication beam, the first portion of the optical communication beam propagating in the fiber core as a high intensity portion of the optical communication beam.

8. A method of free-space optical communication, the method comprising:
guiding, by focusing optics, an optical communication beam emitted from an optical transmitter into a double-clad optical fiber, the optical communication beam carrying data, the double-clad optical fiber having first and second ends, the first end arranged to receive the optical communication beam, the double-clad optical fiber comprising:
a fiber core having a first numerical aperture, the fiber core configured to propagate a first portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber;
a first cladding arranged concentrically around the fiber core, the first cladding having a second numerical aperture equal to or greater than the first numerical aperture, the first cladding configured to propagate a second portion of the optical communication beam from the first end of the double-clad optical fiber to the second end of the double-clad optical fiber; and
a second cladding arranged concentrically around the first cladding; and

directing, by collimating optics, the optical communication beam from the second end of the double-clad optical fiber toward an optical receiver of a communication terminal, the second portion of the optical communication beam arranged concentrically around the first portion of the optical communication beam, the first portion of the optical communication beam having a higher intensity than the second portion of the optical communication beam,
wherein a coupling ratio of the second portion of the optical communication beam to the first portion of the optical communication beam is such that the second portion of the optical communication beam has a lower intensity than the first portion of the optical communication beam at a threshold distance from the collimating optics.

9. A method of free-space optical communication, the method comprising:
guiding, by focusing optics, an optical communication beam emitted from an optical transmitter into a double-clad optical fiber, the optical communication beam carrying data, the double-clad optical fiber having first and second ends, the first end arranged to receive the optical communication beam, the double-clad optical fiber comprising:
a fiber core having a first numerical aperture, the fiber core configured to propagate a first portion of the optical communication beam

Assignees

• Google Inc

Inventors

• Wang Chiachi
• Sholl Michael

Classifications

• H04B10/2581

  Multimode transmission · CPC title

• H04B10/118

  specially adapted for satellite communication · CPC title

• H04B10/1127 Primary

  using two distinct parallel optical paths · CPC title

• G02B6/4204

  the coupling comprising intermediate optical elements, e.g. lenses, holograms (encapsulated active devices H01S5/02208) · CPC title

• G02B6/262

  Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements · CPC title