# US 12,603,702 B2 · Optical amplifier gain self-provisioning

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- Number: US 12,603,702 B2
- Document ID: US12603702B2
- Status: Granted
- Kind: B2
- Application number: 18/466,901
- Filed: 2023-09-14
- Published: 2025-03-20
- Granted: 2026-04-14
- Earliest claimed: 2023-09-14
- Assignees: Cisco Technology, Inc.
- Applicants: Cisco Technology, Inc.
- Inventors: Alberto Arnaldo Tanzi; Giovanni Osnago; Maurizio Gazzola
- Web page: https://patentgrep.com/patent/US12603702B2

## CPC

- H04B 10/07955: {Monitoring or measuring power}
- H04B: TRANSMISSION

## Abstract

An optical network element detects an input optical signal at a preamplifier input and sets an output power level of the preamplifier at a predetermined Automatic Power Reduction (APR) power level. The optical network element starts an APR timer that expires after a first predetermined time period. While the APR timer is running, the optical network element measures an input power level of the input optical signal and calculates a span loss as a function of the difference between the predetermined APR power level and the measured input power level. After the expiration of the APR timer, the optical network element adjusts the output power level of the preamplifier output based on the calculated span loss.

## Claims

### Claim 1

A method comprising:
detecting an input optical signal at a preamplifier input of an optical network element;
setting an output power level of an output optical signal at a predetermined Automatic Power Reduction (APR) power level, the output optical signal generated at a preamplifier output of the optical network element;
starting an APR timer that expires after a first predetermined time period;
after a reset of the APR timer or after an expiration of the APR timer, measuring an input power level of the input optical signal and calculating a span loss as a function of a difference between the predetermined APR power level and the input power level; and
adjusting the output power level of the output optical signal to compensate for the span loss.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
starting a stabilization timer that expires after a second predetermined time period, wherein the second predetermined time period is shorter than the first predetermined time period; and
measuring the input power level of the input optical signal after an expiration of the stabilization timer.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
detecting a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turning off the output optical signal, resetting the APR timer, and resetting the stabilization timer.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
detecting a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turning off the output optical signal and resetting the APR timer.

### Claim 5 (depends on 1)

The method of claim 1, wherein adjusting the output power level comprises adjusting a gain setpoint to compensate for the span loss.

### Claim 6 (depends on 1)

The method of claim 1, wherein the predetermined APR power level is an eye-safe power level.

### Claim 7 (depends on 1)

The method of claim 1, further comprising setting an output power of a booster amplifier of the optical network element based on an insertion loss associated with a multiplexer connected to the booster amplifier.

### Claim 8

An apparatus comprising:
a preamplifier input configured to receive an input optical signal;
a preamplifier output configured to generate an output optical signal; and
a processor coupled to the preamplifier input and the preamplifier output, the processor configured to:
detect the input optical signal at the preamplifier input;
set the preamplifier output to generate the output optical signal at a predetermined Automatic Power Reduction (APR) power level;
start an APR timer that expires after a first predetermined time period;
after a reset of the APR timer or after an expiration of the APR timer, measure an input power level of the input optical signal and calculate a span loss as a function of a difference between the predetermined APR power level and the input power level; and
adjust an output power level of the output optical signal to compensate for the span loss.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the processor is further configured to:
start a stabilization timer that expires after a second predetermined time period, wherein the second predetermined time period is shorter than the first predetermined time period; and
measure the input power level of the input optical signal after an expiration of the stabilization timer.

### Claim 10 (depends on 9)

The apparatus of claim 9, wherein the processor is further configured to:
detect a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turn off the output optical signal, reset the APR timer, and reset the stabilization timer.

### Claim 11 (depends on 8)

The apparatus of claim 8, wherein the processor is further configured to:
detect a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turn off the output optical signal and reset the APR timer.

### Claim 12 (depends on 8)

The apparatus of claim 8, wherein the processor is configured to adjust the output power level by adjusting a gain setpoint for the apparatus to compensate for the span loss.

### Claim 13 (depends on 8)

The apparatus of claim 8, wherein the processor is configured to set the predetermined APR power level at an eye-safe power level.

### Claim 14

One or more non-transitory computer readable storage media encoded with software comprising computer executable instructions that, when the software is executed on optical network element, is operable to cause a processor of the optical network element to:
detect an input optical signal at a preamplifier input of the optical network element;
set an output power level of an output optical signal at a predetermined Automatic Power Reduction (APR) power level, the output optical signal generated at a preamplifier output of the optical network element;
start an APR timer that expires after a first predetermined time period;
after a reset of the APR timer or after an expiration of the APR timer measure an input power level of the input optical signal and calculate a span loss as a function of a difference between the predetermined APR power level and the input power level; and
adjust the output power level of the output optical signal to compensate for the span loss.

### Claim 15 (depends on 14)

The one or more non-transitory computer readable storage media of claim 14, wherein the software is further operable to cause the processor to:
start a stabilization timer that expires after a second predetermined time period, wherein the second predetermined time period is shorter than the first predetermined time period; and
measure the input power level of the input optical signal after an expiration of the stabilization timer.

### Claim 16 (depends on 15)

The one or more non-transitory computer readable storage media of claim 15, wherein the software is further operable to cause the processor to:
detect a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turn off the output optical signal, reset the APR timer, and reset the stabilization timer.

### Claim 17 (depends on 14)

The one or more non-transitory computer readable storage media of claim 14, wherein the software is further operable to cause the processor to:
detect a loss of signal at the preamplifier input; and
while the loss of signal at the preamplifier input is detected, turn off the output optical signal and reset the APR timer.

### Claim 18 (depends on 14)

The one or more non-transitory computer readable storage media of claim 14, wherein the software is further operable to cause the processor to adjust the output power level comprises adjusting a gain setpoint to compensate for the span loss.

### Claim 19 (depends on 14)

The one or more non-transitory computer readable storage media of claim 14, wherein the software is further operable to cause the processor to set the predetermined APR power level at an eye-safe power level.

### Claim 20 (depends on 14)

The one or more non-transitory computer readable storage media of claim 14, wherein the software is further operable to cause the processor to set an output power of a booster amplifier of the optical network element based on an insertion loss associated with a multiplexer connected to the booster amplifier.