# US 2022/0286221 A1 · Optical Node and Optical Transceiver for Auto Tuning of Operational Wavelength

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- Number: US 2022/0286221 A1
- Document ID: US20220286221A1
- Status: Published application
- Kind: A1
- Application number: 17/637,943
- Filed: 2019-09-06
- Published: 2022-09-08
- Earliest claimed: 2019-09-06
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget LM Ericsson (publ)
- Inventors: Roberto Magri; Paolo Debenedetti; Alberto Deho
- Web page: https://patentgrep.com/patent/US20220286221A1

## CPC

- H04J 14/0257: {Wavelength assignment algorithms}
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

An optical node (100) for multiplexing optical signals is disclosed. The optical node (100) comprises an add port (102), a common port (104), an auxiliary port (106), an optical transfer module (110), and a reflecting element (108) coupled to the auxiliary port. The optical transfer module (110) is configured to couple a signal received on the add port (102) and matching an operational wavelength of the optical node (100) to the common port (104), and to couple a signal received on the add port (102) and not matching an operational wavelength of the optical node (100) to the auxiliary port (106). The reflecting element (108) is configured to reflect a signal received on the auxiliary port (106) to the add port (102). Also disclosed are an optical transceiver and methods for operating and optical node and an optical transceiver.

## Claims

### Claim at position 1

-41. (canceled)

### Claim 42

An optical node configured to multiplex optical signals, the optical node comprising:
an add port;
a common port;
an auxiliary port;
an optical transfer module; and
a reflecting element coupled to the auxiliary port, wherein:
the optical transfer module is configured to couple a signal received on the add port to:
the common port, when a wavelength of the signal received on the add port matches an operational wavelength of the optical node, and
the auxiliary port, when the wavelength of the signal received on the add port does not match an operational wavelength of the optical node; and
the reflecting element is configured to reflect a signal received on the auxiliary port to the add port.

### Claim 43 (depends on 42)

The optical node of claim 42, wherein the optical transfer module is configured to couple to the auxiliary port any signal received on the add port that has a wavelength not matching an operational wavelength of the optical node.

### Claim 44 (depends on 42)

The optical node of claim 42, wherein the optical transfer module comprises an optical filtering element, and wherein the optical filtering element comprises:
an add port coupled to the add port of the optical node;
a common port coupled to the common port of the optical node; and
a filter layer configured to couple a signal received on the add port of the optical filtering element to:
the common port of the optical filtering element, when the signal received on the add port of the optical filtering element matches a pass-band of the filter layer; and
the auxiliary port of the optical node, when the signal received on the add port of the optical filtering element does not match a pass-band of the filter layer;
wherein the operational wavelength of the optical node comprises a wavelength matching a pass band of the filter layer.

### Claim 45 (depends on 44)

The optical node of claim 44, wherein the optical filtering element further comprises an express port coupled to the common port of the optical filtering element via the filter layer.

### Claim 46 (depends on 44)

The optical node of claim 44, further comprising:
a plurality of add ports; and
corresponding pluralities of optical filtering elements, auxiliary ports and reflecting elements coupled to the auxiliary ports, wherein:
each add port of the optical node is coupled to an add port of a corresponding optical filtering element;
the filter layer of each optical filtering element is configured to couple any signal received on the add port of the optical filtering element and not matching a pass-band of the filter layer to a respective auxiliary port of the optical node; and
each reflecting element is configured to reflect a signal received on its coupled auxiliary port to the add port of the optical node to which the optical filtering element from which the signal on its coupled auxiliary port was received is coupled.

### Claim 47 (depends on 46)

The optical node of claim 46, wherein each optical filtering element further comprises an express port that is coupled to its common port via its filter layer, and wherein the optical filtering elements are connected in series, such that a signal from a common port of a first optical filtering element is input to an express port of a second optical filtering element.

### Claim 48 (depends on 42)

The optical node of claim 42, wherein the optical node is further configured to demultiplex optical signals, and wherein the optical node further comprises:
a drop port, and
a corresponding optical filtering element, wherein:
the corresponding optical filtering element comprises an express port, a common port, a drop port coupled to the drop port of the optical node, and a filter layer; and
the filter layer is configured to couple a signal received on the express port to:
the drop port, when the signal received on the express port matches a pass-based of the filter layer; and
the common port, when the signal received on the express port does not match a pass-based of the filter layer.

### Claim 49 (depends on 42)

The optical node of claim 42, wherein the optical transfer module is configured to couple a signal received on the add port to the auxiliary port, when the signal received on the add port has a predetermined wavelength that does not match an operational wavelength of the optical node.

### Claim 50 (depends on 42)

The optical node of claim 42, wherein:
the optical transfer module comprises first and second planar regions and a plurality of waveguides coupling the planar regions;
the optical node comprises an Arrayed Waveguide Grating (AWG);
the optical transfer module is configured to couple a signal received on the add port of the AWG to:
the common port of the AWG when the signal received on the add port has a first wavelength, and
the auxiliary port of the AWG when the signal received on the add port has a second wavelength;
the first wavelength is the operational wavelength of the AWG; and
the second wavelength is a wavelength that is adjacent to the operational wavelength of the AWG according to a transfer function of the AWG.

### Claim 51 (depends on 50)

The optical node according to claim 50, wherein a transfer function of the AWG defines a connectivity between:
the add port of the AWG, as an input port; and
the common and auxiliary ports of the AWG, as output ports,
wherein the transfer function is based on wavelength of a signal input to the add port.

### Claim 52 (depends on 50)

The optical node of claim 50, wherein:
the AWG comprises a plurality of add ports and a corresponding plurality of operational wavelengths; and
the optical transfer module is configured to couple signals received on the respective add ports as follows:
to the common port when a wavelength of a signal received on an add port of the AWG matches an operational wavelength of that add port, and
to the auxiliary port when a wavelength of a signal received on an add port of the AWG is adjacent to an operational wavelength of that add port, according to a transfer function of the AWG.

### Claim 53

An optical node configured to multiplex optical signals, the optical node comprising:
an add port;
a common port;
an auxiliary port;
an optical transfer module; and
a monitoring element configured to monitor optical signal power of an optical signal received on the auxiliary port, wherein
the optical transfer module is configured to couple a signal received on the add port to:
the common port, when a wavelength of the signal received on the add port matches an operational wavelength of the optical node, and
the auxiliary port, when the wavelength of the signal received on the add port does not match an operational wavelength of the optical node.

### Claim 54 (depends on 53)

The optical node of claim 53, wherein:
the optical transfer module comprises first and second planar regions and a plurality of waveguides coupling the planar regions;
the optical node comprises an Arrayed Waveguide Grating (AWG) having a plurality of add ports and a corresponding plurality of operational wavelengths;
the optical transfer module is configured to couple signals received on the respective add ports as follows:
to the common port when a wavelength of a signal received on an add port of the AWG matches an operational wavelength of that add port, and
to the auxiliary port when a wavelength of a signal received on an add port of the AWG is adjacent to an operational wavelength of that add port, according to a transfer function of the AWG.

### Claim 55 (depends on 53)

The optical node of claim 53, being further configured to:
receive, at the add port, a plurality of optical signals transmitted by an optical transceiver;
monitor, at the monitoring element, optical signal power received on the auxiliary port;
identify a transmission wavelength at which a power transition of the monitored optical signal power occurs;
select an operational wavelength as a function of the identified transmission wavelength; and
communicate the selected operational wavelength to the optical transceiver.

### Claim 56

A method performed by a controller of an optical transceiver, wherein the optical transceiver comprises a tunable laser configured to generate an optical signal, a port configured to transmit the generated optical signal and to receive an optical signal, and a received signal monitoring element configured to monitor optical signal power of an optical signal received on the port, wherein the method comprises:
causing the tunable laser to scan over wavelengths from a candidate set of transmission wavelengths;
monitoring optical signal power received on the transmission port;
identifying a transmission wavelength at which a power transition of the monitored optical signal power takes place;
selecting an operational wavelength as a function of the identified transmission wavelength; and
causing the tunable laser to generate an optical signal at the selected operational wavelength.

### Claim 57 (depends on 56)

The method of claim 56, wherein:
identifying a transmission wavelength at which a power transition of the monitored optical signal power takes place comprises identifying a transmission wavelength at which the monitored optical signal power falls below a threshold value associated with a minimum predicted signal power of an optical signal received on the transmission port; and
the identified transmission wavelength is selected as the operation wavelength.

### Claim 58 (depends on 56)

The method of claim 56, wherein:
identifying a transmission wavelength at which a power transition of the monitored received optical signal power takes place comprises identifying a transmission wavelength at which the monitored optical signal power rises above a threshold value associated with a minimum predicted signal power of an optical signal received on the transmission port; and
selecting an operational wavelength as a function of the identified transmission wavelength comprises selecting as the operation wavelength a wavelength that is adjacent in a candidate set of transmission wavelengths to the identified transmission wavelength.

### Claim 59 (depends on 58)

The method of claim 58, wherein to the operational wavelength is selected based on a transfer function of an optical node to which the port of the optical transceiver is connected.

### Claim 60 (depends on 56)

The method of claim 56, wherein causing the tunable laser to scan over wavelengths from a candidate set of transmission wavelengths comprises: generating an initial optical signal at a seed wavelength, and modifying the wavelength of the generated optical signal according to a set of scanning parameters.

### Claim 61

A method performed by a controller of an optical transceiver, wherein the optical transceiver comprises a tunable laser configured to generate an optical signal and a port configured to transmit the generated optical signal and to receive an optical signal, wherein the method comprises:
causing the tunable laser to scan over wavelengths from a candidate set of transmission wavelengths;
receiving a control signal communicating an operational wavelength for the transceiver; and
causing the tunable laser to generate an optical signal at the selected operational wavelength.