# US 8,542,965 B2 · Bidirectional optical link over a single multimode fiber or waveguide

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- Number: US 8,542,965 B2
- Document ID: US8542965B2
- Status: Granted
- Kind: B2
- Application number: 12/711,733
- Filed: 2010-02-24
- Published: 2010-11-11
- Granted: 2013-09-24
- Earliest claimed: 2007-12-18
- Assignees: Analog Devices, Inc.
- Applicants: Shrenik Deliwala
- Inventors: Shrenik Deliwala
- Web page: https://patentgrep.com/patent/US8542965B2

## CPC

- G02B 6/4246: {Bidirectionally operating package structures}
- H04B 10/40: Transceivers
- H10F 55/00: Radiation-sensitive semiconductor devices covered by groups H10F10/00, H10F19/00 or H10F30/00 being structurally associated with electric light sources and electrically or optically coupled thereto
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04B: TRANSMISSION
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A transceiver for use in a bidirectional optical communication link over a multimode channel is provided. The transceiver includes a single transverse mode light source in a transmitter. A waveguide or fiber based bidirectional coupler projects the transmitter mode to the high modes of the multimode channel. A detector coupled to predominantly all the modes of the channel via the waveguide or fiber based bidirectional coupler.

## Claims

### Claim 1

A system for bidirectional optical communication over a multi mode channel, the system comprising:
at least two transceivers on opposing ends of the multi mode channel, each of the transceivers comprising:
a single transverse mode light source in a transmitter;
a bidirectional coupler that projects the single transverse mode to higher order modes of the multi mode channel; and
a detector in a receiver, the detector coupled to modes of the multi mode channel via the bidirectional coupler,
wherein the bidirectional coupler comprises an optical splitter in which one branch is connected to the transmitter and the other branch is connected to the receiver, the optical splitter configured to couple substantially more light from the multi mode channel to the detector than to the transmitter.

### Claim 2 (depends on 1)

The system of claim 1, wherein at least one of the bidirectional couplers comprises an adiabatically tapered section that transmits the single transverse mode to a region that projects the single transverse mode to the higher order modes of the multi mode channel.

### Claim 3 (depends on 1)

The system of claim 1, wherein at least one of the bidirectional couplers comprises polymer waveguides/fibers.

### Claim 4 (depends on 1)

The system of claim 1, wherein at least one of the bidirectional couplers comprises glass waveguides/fibers.

### Claim 5 (depends on 1)

The system of claim 1, wherein the optical splitter is configured such that overall coupling of light from the transmitter of a first transceiver to the transmitter of a second transceiver is less than about −30 dB, while overall coupling of light from the transmitter of the first transceiver to the detector of the second transceiver is greater than about −6 dB.

### Claim 6

A transceiver for use in bidirectional optical communication over a multi mode channel, the transceiver comprising:
a single transverse mode light source;
a bidirectional coupler that projects the single transverse mode to the higher order modes of the multimode channel to propagate in a first direction along the multi mode channel; and
a detector coupled to modes of the channel via the bidirectional coupler and configured to receive an optical signal propagating in a second direction along the multi mode channel, the second direction opposite to the first direction,
wherein the bidirectional coupler comprises an optical splitter in which one branch is coupled to the light source and the other branch is coupled to the detector, the optical splitter configured to couple substantially more light from the multi mode channel to the detector than to the light source.

### Claim 7 (depends on 6)

The transceiver of claim 6, wherein the bidirectional coupler comprises an adiabatically tapered section that transmits the single transverse mode to a region that projects the single transverse mode to the higher order modes of the multi mode channel.

### Claim 8 (depends on 6)

The transceiver of claim 6, wherein the bidirectional coupler comprises polymer waveguides/fibers.

### Claim 9 (depends on 6)

The transceiver of claim 6, wherein the bidirectional coupler comprises glass waveguides/fibers.

### Claim 10 (depends on 6)

The transceiver of claim 6, wherein the optical splitter is configured such that overall coupling of light from the multi mode fiber to the light source is less than about −30 dB, while overall coupling of light from the multi mode fiber to the detector of the second transceiver is greater than about −6 dB.