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US 12,574,116 B2Granted
Free space optical communications terminal
AssigneeAirbus SAS
InventorsCrisanto Quintana Sanchez, Gavin Erry, Yoann Thueux
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Abstract
A free space optical communications terminal (100) including an optical arrangement of a quarter-wave plate (105), a Faraday rotator (110), a polarisation splitter (115), a first arm (120) comprising a receiver (126) and a transmitter (128), and a second arm (130) comprising a component (132) configured to utilise a received beam. The optical arrangement apportions a circularly polarised beam between the first and second arm.
Claims15
A free space optical communications terminal comprising:
- a quarter-wave plate;
- a Faraday rotator comprising an electromagnetic element;
- a polarisation splitter,
- a first arm comprising a receiver and a transmitter;
- and
- a second arm comprising a component configured to utilise a received beam;
- wherein the quarter wave plate, the Faraday rotator, and the polarisation splitter are arranged along a principal axis of the free-space optical communications terminal and are configured for a received circularly polarised beam incident on the quarter-wave plate;
- wherein the quarter-wave plate converts the received circularly polarised beam to a received linearly polarised beam;
- wherein the Faraday rotator rotates a polarisation of the received linearly polarised beam to produce a rotated received linearly polarised beam;
- the polarisation splitter provides a first portion of the rotated received linearly polarised beam to the first arm and a second portion of the rotated received linearly polarised beam to the second arm;
- wherein for a transmitted beam produced by the transmitter of the first arm and incident on the polarisation splitter, the polarisation splitter provides a transmitted linearly polarised beam to the Faraday rotator;
- wherein the Faraday rotator rotates a polarisation of the transmitted linearly polarised beam to produce a rotated transmitted linearly polarised beam;
- wherein the quarter-wave plate converts the rotated transmitted linearly polarised beam to an output beam with an output polarisation, and
- wherein a strength of a magnetic field applied by the electromagnetic element to the input beam is variable such the rotation of the polarisation imparted by the Faraday rotator to the input beam is variable.
11 more elements
A method for free space optical communications using a terminal including a quarter-wave plate;
- a Faraday rotator;
- a polarisation splitter;
- a first arm comprising a receiver and a transmitter;
- and a second arm comprising a component configured to utilise a received beam;
- the method comprising:
- generating, using the transmitter, an output beam of light encoding information to be communicated, the output beam having a first linear polarisation;
- rotating, using the Faraday rotator, the output beam from a first linear polarisation to a second linear polarisation;
- and
- transforming, using the quarter-wave plate, the output beam from a second linear polarisation to a third polarisation to be transmitted to a target;
- receiving an input beam of light encoding information to be communicated, the input beam having a fourth polarisation;
- transforming, using the quarter-wave plate, the input beam from the fourth polarisation to a fifth polarisation;
- rotating, using the Faraday rotator, the input beam from the fifth polarisation to a sixth polarisation;
- splitting, using the polarisation splitter, the input beam between the first arm and the second arm and receiving a portion of the input beam at the receiver, and
- transforming, using the quarter-wave plate, and rotating, using the Faraday rotator, the input beam to change a ratio of the input beam split during the splitting of the input beam between the first arm and the second arm.
11 more elements
Dependencies are inferred from the claim text.