# US 12,191,982 B2 · Optical transmission device

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- Number: US 12,191,982 B2
- Document ID: US12191982B2
- Status: Granted
- Kind: B2
- Application number: 17/954,388
- Filed: 2022-09-28
- Published: 2023-06-29
- Granted: 2025-01-07
- Earliest claimed: 2021-12-27
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Atsushi Kiyama; Nobuyuki Fukuchi; Tomoaki Watanabe
- Web page: https://patentgrep.com/patent/US12191982B2

## CPC

- H04B 10/296: Transient power control, e.g. due to channel add/drop or rapid fluctuations in the input power
- H04J 14/0212: {using optical switches or wavelength selective switches [WSS]}
- H04J 14/0221: {Power control, e.g. to keep the total optical power constant}
- H04J 14/02216: {by gain equalization}
- H04Q 11/0005: {Switch and router aspects}
- H04B 10/07955: {Monitoring or measuring power}
- H04Q 2011/0016: {using wavelength multiplexing or demultiplexing}
- H04B: TRANSMISSION
- 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)
- H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W)

## Abstract

An optical transmission device includes: a selector configured to select a wavelength of a signal to be transmitted to an optical transmission line and output a wavelength-multiplexed signal; an adjustor configured to control a power level of the wavelength-multiplexed signal; and a controller configured to control the adjustor or the selector, wherein the selector selects a wavelength of an optical signal in a second wavelength band different from an existing first wavelength band, and when the second wavelength band is added to or removed from the optical transmission line, the controller controls power of the wavelength-multiplexed signal in the second wavelength band at a slower speed than power control in the first wavelength band.

## Claims

### Claim 1

An optical transmission device comprising:
a first wavelength selective switch for a first wavelength band with a shorter wavelength than a second wavelength band;
a first wavelength selective switch controller configured to control an output power of the first wavelength selective switch;
a first variable optical attenuator coupled to an output of the first wavelength selective switch and configured to control the output power of the first wavelength selective switch;
a first variable optical attenuator controller configured to control the first variable optical attenuator;
a second wavelength selective switch for the second wavelength band;
a second wavelength selective switch controller configured to control an output power of the second wavelength selective switch;
a second variable optical attenuator coupled to an output of the second wavelength selective switch and configured to control the output power of the second wavelength selective switch;
a second variable optical attenuator controller configured to control the second variable optical attenuator; and
a coupler configured to multiplex an output of the first variable optical attenuator and an output of the second variable optical attenuator,
the first variable optical attenuator controller, when the first wavelength band is added to or removed from the optical transmission device, controls the first variable optical attenuator at a slower speed than a control speed of the second wavelength selective switch, and the second variable optical attenuator controller, when the second wavelength band is added to or removed from the optical transmission device, controls the second variable optical attenuator at a slower speed than a control speed of the first wavelength selective switch.

### Claim 2 (depends on 1)

The optical transmission device according to claim 1, wherein the second variable optical attenuator controller more slowly changes an adjustment amount for each wavelength set in the adjustor than the control speed of the first wavelength selective switch when the second wavelength band is added or removed.

### Claim 3 (depends on 2)

The optical transmission device according to claim 2, wherein the second variable optical attenuator controller changes a power adjustment amount of a wavelength-multiplexed signal in the second wavelength band, using a second time constant larger than a first time constant of a power control in the first wavelength band, when the second wavelength band is added or removed.

### Claim 4 (depends on 2)

The optical transmission device according to claim 2, wherein the second variable optical attenuator controller changes a power adjustment amount of a wavelength-multiplexed signal in the second wavelength band, by receiving a convergence notification of the power control in the first wavelength band, when the second wavelength band is added or removed.

### Claim 5 (depends on 1)

The optical transmission device according to claim 1, wherein, when the second wavelength band is added, the second variable optical attenuator controller transmits a wavelength-multiplexed signal in the second wavelength band to the optical transmission device at a first power level lower than a target power level, and increases the power level of the wavelength-multiplexed signal stepwise until the power level reaches the target power level.

### Claim 6 (depends on 1)

The optical transmission device according to claim 1, wherein, when the second wavelength band is removed, the second variable optical attenuator controller transmits a wavelength-multiplexed signal in the second wavelength band to the optical transmission device at a second power level lower than a current power level, and reduces the power level of the wavelength-multiplexed signal stepwise until the power level reaches a predetermined shutdown level.

### Claim 7 (depends on 1)

The optical transmission device according to claim 1, wherein the optical transmission device is a ROADM node connected to an optical network.

### Claim 8 (depends on 1)

The optical transmission device according to claim 1, wherein the second wavelength band is a wavelength band on a longer wavelength side than the first wavelength band.