# US 9,438,969 B2 · Optical multiplexor switch for free space optical communication

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- Number: US 9,438,969 B2
- Document ID: US9438969B2
- Status: Granted
- Kind: B2
- Application number: 14/335,693
- Filed: 2014-07-18
- Published: 2016-01-21
- Granted: 2016-09-06
- Earliest claimed: 2014-07-18
- Assignees: Raytheon Company
- Applicants: Raytheon Company
- Inventors: John F. Silny; Gary D. Coleman
- Web page: https://patentgrep.com/patent/US9438969B2

## CPC

- H04Q 11/0005: {Switch and router aspects}
- G02B 6/262: {Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements}
- G02B 6/3518: {the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device (MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833)}
- H04Q 2011/0009: {using wavelength filters}
- H04Q 2011/0015: {using splitting combining}
- H04Q 2011/0016: {using wavelength multiplexing or demultiplexing}
- H04Q 2011/0026: {using free space propagation (e.g. lenses, mirrors)}
- H04Q 2011/003: {using switches based on microelectro-mechanical systems [MEMS]}
- H04Q 2011/0039: {Electrical control}
- H04Q 2011/0043: {Fault tolerance}
- H04Q 2011/0047: {Broadcast; Multicast}
- H04Q 2011/0049: {Crosstalk reduction; Noise; Power budget}
- H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

Device and method for optically switching a plurality of optical input signals include: receiving the plurality of optical input signals, wherein one or more of the optical input signals represent multiple channels at different channel frequencies; collimating the received plurality of optical input signals; removing noise between the channels by a comb filter; dispersing the collimated optical signals so that signals of different wavelength are separated by different angles; focusing the optical signals separated by different angles on a light switch device having a plurality of micromirrors; and controlling the light switch by a control signal to direct one or more of the optical signals separated by different angles to one or more output fibers for multicasting of the optical input signals.

## Claims

### Claim 1

A method for optically switching a plurality of optical input signals, the method comprising:
receiving the plurality of optical input signals, wherein one or more of the optical input signals represent multiple channels at different channel frequencies;
spreading the received plurality of optical input signals by an anamorphic optical element;
collimating the spread plurality of optical signals to a portion of rows of a light switch, wherein the light switch comprises of a single beam steering array having a plurality of microelements arranged in a horizontal direction and a vertical direction;
dispersing the collimated optical signals so that signals of different wavelength are separated by different angles;
focusing the optical signals on the light switch device, wherein the light from a channel on a single input fiber is spread over multiple microelements of the light switch;
controlling the light switch by a control signal to direct one or more of the optical signals separated by different angles to one or more output fibers for multicasting of the optical input signals, wherein each of said one or more output fibers accepts optical inputs from any row and column of the light switch; and
addressing the microelements to tailor a precise spectral limits of the channel, and to send a fraction of the incident light to each output fiber, and performing noise filtering by altering a region on the light switch that act together for each multiple channel.

### Claim 2 (depends on 1)

The method of claim 1, wherein the light switch is a Digital Micro-mirror Device (DMD) including a plurality of micromirrors and the control signal tilts a portion of the plurality of the micromirrors to direct said one or more of the optical signals.

### Claim 3 (depends on 1)

The method of claim 1, wherein the light switch is an LCoS chip including a plurality of liquid crystal elements arranged in an array and the control signal controls phases of the liquid crystal elements to direct said one or more of the optical signals.

### Claim 4 (depends on 1)

The method of claim 1, wherein the light switch is an Optical Phased Array.

### Claim 5 (depends on 1)

The method of claim 1, further comprising separating color spectrums in the collimated optical signals in different angles.

### Claim 6 (depends on 1)

The method of claim 1, further comprising absorbing light from channel that do not contain signal by a light trap.

### Claim 7 (depends on 6)

The method of claim 6, wherein the light trap is a plurality of carbon nano tubes.

### Claim 8 (depends on 1)

The method of claim 1, further comprising mapping channels onto a two-dimensional grid, with the channels from an individual input port distributed spectrally along a horizontal axis, and the same spectral channel from different input ports arranged along a vertical axis.

### Claim 9 (depends on 1)

The method of claim 1, further comprising performing wavelength division multiplexing to provide a plurality of communications channels at different wavelengths for the directed optical signals.

### Claim 10

An optical device for optically switching a plurality of optical input signals comprising:
a plurality of input fibers for receiving the plurality of optical input signals, wherein one or more of the optical input fibers represent multiple channels at different channel frequencies;
an anamorphic lens for spreading the received plurality of optical input signals;
a collimator for collimating the spread plurality of optical input signals;
a dispersing element for dispersing the collimated optical signals so that signals of different wavelength are separated by different angles;
a focusing element for focusing the optical signals separated by different angles, wherein the light from a channel on a single input fiber is spread over multiple microelements of the light switch;
a light switch having a plurality of microelements arranged in a horizontal direction and a vertical direction for receiving the focused signals, wherein the collimator collimates the spread plurality of optical input signals to a portion of the rows of the microelements of the light switch via the dispersing element, wherein the light switch comprises of a single beam steering array having a plurality of microelements arranged in a horizontal direction and a vertical direction; and
a controller for issuing a control signal to tilt a portion of the plurality of the elements to direct one or more of the optical signals separated by different angles to one or more output fibers for multicasting of the optical input signals, and for addressing the microelements to tailor a precise spectral limits of the channel and to send a fraction of the incident light to each output fiber, and performing noise filtering by altering a region on the light switch that act together for each multiple channel, wherein each of said one or more output fibers accepts optical inputs from any row and column of the light switch.

### Claim 11 (depends on 10)

The optical device of claim 10, wherein the light switch is a Digital Micro-mirror Device (DMD) including a plurality of micromirrors and the control signal tilts a portion of the plurality of the micromirrors to direct said one or more of the optical signals.

### Claim 12 (depends on 10)

The optical device of claim 10, wherein the light switch is an LCoS chip including a plurality of liquid crystal elements arranged in an array and the control signal controls phases of the liquid crystal elements to direct said one or more of the optical signals.

### Claim 13 (depends on 10)

The optical device of claim 10, wherein the light switch is an Optical Phased Array.

### Claim 14 (depends on 10)

The optical device of claim 10, further comprising a light trap for absorbing light from channels that do not contain a signal.

### Claim 15 (depends on 14)

The optical device of claim 14, wherein the light trap is a plurality of carbon nano tubes.

### Claim 16 (depends on 10)

The optical device of claim 10, further comprising a two-dimensional grid for having channels with noise mapped onto, with the channels from an individual input port distributed spectrally along a horizontal axis, and the same spectral channel from different input ports arranged along a vertical axis.

### Claim 17 (depends on 10)

The optical device of claim 10, wherein the optical device is mounted on a satellite or airborne platform.

### Claim 18 (depends on 10)

The optical device of claim 10, further comprising a Fabry-Perot filter.