US 7,627,251 B2 · Wavelength division and polarization division multiple access free space optical terminal using a single aperture

Abstract

A communication device uses one or two stacks of reflective deflectors to steer the electromagnetic waves carrying signals received and transmitted through a single telescope/aperture device. The signals outside the device may be circularly polarized while inside the device they are linearly polarized most of the time. The deflectors within each stack are transparent to the signals steered by the deflectors behind them. Since the deflecting wave band may shift with the changing angle of incidence of the signals due to steering, the wave bands are sufficiently spaced apart. When the signals impact the deflectors at nearly normal angles, the wave bands can be made more narrow. When more than one stack of deflectors is used, the spacing between the wave bands within one stack may be utilized by another stack. Beam splitters and a variety of other optical devices (such as quarter wave plates, half wave plates, Faraday rotators, and equivalent devices) are used to separate signals for further processing within the device. Instead of reflective deflectors, the device may generally use stacks of transmissive deflectors for similar effect in a similar way.

Claims78

Dependent claims

A communication device comprising:

an aperture structure;
and
wavelength dependent deflectors deflecting respective electromagnetic signals of respective wavelengths at different respective wavelength dependent angles to simultaneously, dynamically and independently steer the electromagnetic signals passing through the aperture structure in different wavelength dependent angular directions through free space to or from remote receiver or transmitter devices at different angular locations.

A communication device comprising:

an aperture structure configured to receive and/or transmit electromagnetic signals;
a polarization element configured to alter a polarization of the electromagnetic signals;
a polarizing splitting element configured to split the electromagnetic signals into first and second electromagnetic signals based on an altered polarization of the electromagnetic signals;
a first stack of deflectors deflecting first respective electromagnetic signals of respective wavelengths at respective angles, individual deflectors in the first stack deflecting substantially all first electromagnetic signals within the individual deflectors' respective non-overlapping wavelength band and passing first electromagnetic signals deflected by other deflectors in the first stack, with at least one deflector in the first stack deflecting substantially all first signals within a wavelength band;
a second stack of deflectors defecting second respective electromagnetic signals of respective wavelengths at respective angles, individual deflectors in the second stack deflecting substantially all second electromagnetic signals within the individual deflectors' respective non-overlapping wavelength band and passing second electromagnetic signals deflected by other deflators in the second stack, with at least one deflector in the second stack deflecting substantially all second electromagnetic signals within a wavelength band;
a first polarization rotation device positioned so that the first electromagnetic signals pass through the first polarization rotation device before being deflected by the first stack of deflectors and, after being deflected, pass through the first polarization rotation device and then pass through the polarizing splitting element;
and
a second polarization rotation device positioned so that the second electromagnetic signals pass through the second polarization rotation device before being deflected by the second stack of deflectors and, after being deflected, pass through the second polarization rotation device and then pass through the polarizing splitting element.

5 more elements

A communication device comprising:

an aperture structure;
a stack of deflectors deflecting respective electromagnetic signals of respective wavelengths at respective angles, the electromagnetic signals passing through the aperture structure, a defector in the stack passing a signal deflected by another deflector in the stack;
a polarization beam splitter coupled to the aperture structure and the stack;
a signal path coupled to the polarization beam splitter;
and
a linear/circular polarization device, positioned so that electromagnetic signals deflected by at least one of the deflectors in the stack, are deflected at nearly normal angle, are linearly polarized when leaving and entering the polarization beam splitter, and, before being deflected, pass through the polarization beam splitter and then pass through the linear/circular polarization device and, after being deflected, pass through the linear/circular polarization device and then pass through the polarization beam splitter, the deflectors in the stack being reflectors.

3 more elements

A communication device comprising:

an aperture structure;
a stack of deflectors deflecting respective electromagnetic signals of respective wavelengths at respective angles, the electromagnetic signals passing through the aperture structure, a defector in the stack passing a signal deflected by another deflector in the stack;
a polarization beam splitter coupled to the aperture structure and the stack;
a signal path coupled to the polarization beam splitter;
and
a polarization rotation device, positioned so that electromagnetic signals deflected by at least one of the deflectors in the stack, are deflected at nearly normal angle, are linearly polarized when leaving and entering the polarization beam splitter, and, before being deflected, pass through the polarization beam splitter and then pass through the polarization rotation device and, after being deflected, pass through the polarization rotation device and then pass through the polarization beam splitter, the deflectors in the stack being reflectors.

3 more elements

A method for communication comprising:

passing of electromagnetic signals by an aperture structure;
deflecting respective electromagnetic signals of respective wavelengths at respective angles by a stack of deflectors;
passing a signal to a deflector in the stack, deflected by another deflector in the stack;
coupling a polarization beam splitter to the aperture structure and the stack;
coupling a signal path to the polarization beam splitter;
and
positioning a linear/circular polarization device so that electromagnetic signals deflected by at least one of the deflectors in the stack, are deflected at nearly normal angle, are linearly polarized when leaving and entering the first polarization beam splitter, and, before being deflected, first pass through the polarization beam splitter and then pass through the linear/circular polarization device and, after being deflected, pass through the linear/circular polarization device and then pass through the polarization beam splitter, the deflectors in the stack being reflectors.

4 more elements

A method for communication comprising:

passing of electromagnetic signals by an aperture structure;
deflecting respective electromagnetic signals of respective wavelengths at respective angles by a stack of deflectors;
passing a signal to a deflector in the stack, deflected by another deflector in the stack;
coupling a polarization beam splitter to the aperture structure and the stack;
coupling a signal path to the polarization beam splitter;
and
positioning a polarization rotation device so that electromagnetic signals deflected by at least one of the deflectors in the stack, are deflected at nearly normal angle, are linearly polarized when leaving and entering the polarization beam splitter, and, before being deflected, first pass through the polarization beam splitter and then pass through the polarization rotation device and, after being deflected, first pass through the polarization rotation device and then pass through the polarization beam splitter, the deflectors in the stack being reflectors.

4 more elements

Dependencies are inferred from the claim text.

Wavelength division and polarization division multiple access free space optical terminal using a single aperture

Life of this patent

Wavelength division and polarization division multiple access free space optical terminal using a single aperture

Life of this patent

Abstract

Claims78