Optical Receiver Module Gain Saturation Control

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Solution Overview

Problem

Conventional semiconductor optical amplifier (SOA) control methods either cause loss through optical branching or lack effective control without branching, leading to gain saturation issues.

Innovation Solution

An optical receiver module with a variable optical attenuator and a controller that adjusts the SOA to operate within a non-saturation region by estimating power based on suppressed and extracted wavelength bands, without the need for optical branching, using an optical filter to separate signal and ASE noise for accurate power estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical branching is used to monitor input power for VOA control, then accurate power monitoring is achieved, but loss occurs in the optical path

Engineering Contradiction:

Improvepower monitoring accuracyVSAvoidoptical loss

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

An optical filter is introduced as an intermediary component to separate the wavelength band of interest from the total optical signal. This allows power monitoring of specific wavelength components without requiring physical optical branching, thereby achieving accurate measurement while minimizing energy loss in the main optical path.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If optical branching is avoided for VOA control, then optical loss is reduced, but effective power monitoring becomes difficult

Engineering Contradiction:

Improveoptical lossVSAvoidpower monitoring difficulty

Core Design Contradiction:

Loss of energyVSDifficulty of detecting and measuring

Solution Approach 1:

The optical filter serves as a mediator that enables power monitoring without optical branching. By filtering specific wavelength bands before detection, the system can accurately measure power levels while keeping the main optical path intact and minimizing energy loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/optical branching approach with a wavelength-selective filtering approach. Instead of physically splitting the optical path to monitor power, the system uses spectral filtering to isolate and measure specific wavelength components, simplifying the control mechanism while reducing optical loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Power

If SOA amplification is increased to handle burst signals, then signal strength is improved, but gain saturation occurs

Engineering Contradiction:

Improvesignal strengthVSAvoidgain saturation

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The system implements feedback control by monitoring the power of amplified signals through optical filtering and detection. The VOA is dynamically adjusted based on this feedback to maintain the SOA operating point within the linear amplification region, preventing gain saturation while ensuring sufficient signal strength for burst signals.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent employs dynamic control of the VOA attenuation based on real-time monitoring of SOA output power. This dynamic adjustment allows the system to adapt to varying input signal conditions and maintain optimal SOA operation, preventing gain saturation during high-power burst signals while maximizing amplification when needed.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables effective power control and suppression of gain saturation without optical branching, ensuring appropriate output in optical receiving control, even with burst signals, by utilizing the optical filter to separate and analyze signal and ASE noise.

Implementation Method 1

an optical filter configured to separate the third optical signal into: a signal obtained by suppressing the outside portion of a wavelength band of the first optical signal in the third optical signal; and ASE noise obtained by extracting the outside portion of the wavelength band

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a semiconductor optical amplifier configured to amplify the second optical signal to output a third optical signal

Methodology Applied

Scientific EffectSemiconductor optical amplification:

Implementation Method 3

a variable optical attenuator configured to adjust the first optical signal to output a second optical signal

Methodology Applied

Scientific EffectOptical attenuation:

Data Source

PatentUS11095375B2Optical receiver module, optical receiving method, optical line terminal, PON system, and optical filter

Publication Date: 2021.08.17 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

An optical receiver module which receives a first optical signal including a continuous signal or a burst signal includes: a variable optical attenuator which adjusts the first optical signal to output a second optical signal; a semiconductor optical amplifier which amplifies the second optical signal to output a third optical signal; and a controller which controls an output of at least one of the variable optical attenuator and the semiconductor optical amplifier so as to cause the semiconductor optical amplifier to operate in a region in which gain saturation of the semiconductor optical amplifier does not occur, on the basis of at least one of: a power obtained by suppressing an outside portion of the wavelength band of the first optical signal in the third optical signal; and a power obtained by extracting the outside portion of the wavelength band of the first optical signal in the third optical signal.