Passive Optical Network Using Quantum-Dot and Multi-Quantum-Well Amplifiers

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Solution Overview

Problem

Conventional passive optical networks experience performance deterioration due to the non-linearity of semiconductor optical amplifiers causing central wavelength shifts during direct modulation, leading to signal loss and chirp-related issues.

Innovation Solution

A passive optical network utilizing quantum-dot reflective semiconductor amplifiers at the central office and multi-quantum-well reflective semiconductor amplifiers at optical network units, which offset central wavelengths to prevent signal loss and compensate for chirp effects, thereby improving signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional semiconductor optical amplifier with direct modulation is used, then the device complexity is reduced and ease of operation is improved, but the central wavelength shifts toward longer wavelengths due to non-linearity and positive chirp, causing signal loss and performance deterioration

Engineering Contradiction:

Improvedirect modulation capabilityVSAvoidsignal quality

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the physical parameters of the semiconductor optical amplifier by using quantum-dot type materials instead of conventional materials. This parameter change in the amplifier type eliminates positive chirp during direct modulation, preventing wavelength drift while maintaining direct modulation capability, thus resolving the contradiction between ease of operation and signal quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of wavelength drift by using offset wavelength injection scheme. The wavelength drift that would normally cause signal loss is compensated by intentionally offsetting the injection wavelength, transforming the harmful wavelength shift into a manageable parameter that can be compensated, thereby maintaining signal quality while preserving direct modulation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Device complexity

If conventional semiconductor optical amplifiers are used in both downstream and upstream, then device complexity is minimized, but wavelength drift occurs in both directions causing network performance deterioration

Engineering Contradiction:

Improvelight source configurationVSAvoidnetwork performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies different types of semiconductor optical amplifiers at different locations in the network. Quantum-dot type amplifiers are used at the central office for downstream transmission, while multi-quantum-well type amplifiers are used at optical network units for upstream transmission. This local differentiation allows each amplifier to be optimized for its specific function, preventing wavelength drift issues while maintaining overall network performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry in the light source configuration by using different amplifier types for downstream and upstream transmissions. The quantum-dot amplifier at the central office has different characteristics than the multi-quantum-well amplifier at the optical network units, creating an asymmetric configuration that compensates for wavelength drift in both transmission directions

Inventive Principle:

Principle #4Asymmetry

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

This configuration minimizes receiver sensitivity penalties and maintains communication performance by offsetting central wavelengths, preventing signal loss and distortion caused by chirp phenomena.

Implementation Method 1

a plurality of first reflective semiconductor optical amplifiers of a quantum-dot type, each of which generates a wavelength-seeded downstream optical signal

Methodology Applied

Scientific EffectQuantum confinement effect:

Implementation Method 2

a plurality of optical network units each of which includes a second reflective semiconductor optical amplifier of a multi-quantum-well type, the second reflective semiconductor optical amplifier generating a wavelength-seeded upstream optical signal

Methodology Applied

Scientific EffectQuantum well effect:

Implementation Method 3

a Fabry-Perot laser capable of generating wavelength-seeded light

Methodology Applied

Scientific EffectOptical resonance:

Data Source

PatentUS7447435B2Passive optical network

Publication Date: 2008.11.04 SAMSUNG ELECTRONICS CO LTD

AI summary

Disclosed is a passive optical network comprising a central office including a plurality of first reflective semiconductor optical amplifiers of a quantum-dot type, each of which generates a wavelength-seeded downstream optical signal on a downstream channel of a corresponding wavelength, a plurality of optical network units each of which includes a second reflective semiconductor optical amplifier of a multi-quantum-well type, the second reflective semiconductor optical amplifier generating a wavelength-seeded upstream optical signal on an upstream channel of a corresponding wavelength and a remote node for outputting the downstream optical signals to corresponding optical network units, and multiplexing and outputting the upstream optical signals to the central office.