Reflective Optical Amplifier Self-Seeding for Dynamic Wavelength Assignment

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Solution Overview

Problem

The deployment of self-seeding transmitters in telecommunications networks is limited by the need for partially reflective elements, which increase costs and are not easily integratable into silicon photonics, and are restricted to tree-and-branch topologies with fixed wavelength assignments, making them unsuitable for next-generation access networks with varying topologies and dynamic configurability requirements.

Innovation Solution

An optical system where a second reflective optical amplifier at an optical link end provides the seeding signal to a first reflective optical amplifier, eliminating the need for partially reflective elements at remote nodes and allowing for dynamic wavelength assignment and compatibility with various network topologies, including tree-and-branch, ring, and mesh networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If partially reflective elements are used for seeding, then wavelength locking is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvewavelength lockingVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the seeding function from a separate component (partially reflective element) and integrates it into the existing reflective optical amplifier. The RSOA performs both amplification and seeding functions by reflecting a portion of its own output signal back through the WDM filter, eliminating the need for additional seeding components and reducing device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The reflective optical amplifier is given multiple functions: it serves as both the light source for upstream transmission and the seed generator for wavelength locking. By utilizing the RSOA's inherent reflectivity and the WDM filter's spectral selection, the system achieves wavelength stabilization without requiring dedicated seeding hardware.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If partially reflective elements are deployed, then self-seeding is enabled, but ease of manufacture decreases

Engineering Contradiction:
Improveself-seeding capabilityVSAvoidease of manufacture
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The system enables self-service by allowing the RSOA to generate its own seed signal from its own output. The reflected signal from the WDM filter is fed back into the RSOA, creating a self-contained seeding mechanism that eliminates the need for external seeding components and simplifies manufacturing processes.

Inventive Principle:
Principle #25Self-service

3Reliability

If fixed wavelength assignment is used, then self-seeding transmitter works, but adaptability decreases

Engineering Contradiction:
Improveself-seeding operationVSAvoidadaptability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic configurability through electronically controllable wavelength selection. The WDM filter can be reconfigured to different wavelength channels, and the RSOA's lasing wavelength can be tuned by adjusting its drive current. This enables the system to adapt to different network topologies and wavelength assignments while maintaining self-seeding operation.

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

This configuration reduces costs, simplifies installation, and enables dynamic wavelength management and bi-directional communication on the same wavelength, enhancing the flexibility and efficiency of optical transmitter seeding in diverse network environments.

Implementation Method 1

The second reflective optical amplifier is configured to provide the first optical seed signal by reflecting a portion of the first optical signal back to the first reflective optical amplifier

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

A wavelength division multiplexer (WDM), in the form of an arrayed waveguide grating (AWG), at a remote node reflects a spectral slice of the broadband light back to the terminal for use as a seeding light

Methodology Applied
Scientific EffectWavelength division multiplexing:

Data Source

PatentEP3747140B1Optical system and method for seeding an optical transmitter
Publication Date: 2022.11.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3747140B1 patent drawingFigure 1
  • EP3747140B1 patent drawingFigure 2
  • EP3747140B1 patent drawingFigure 3A~3C

AI summary

An optical system (200,400) and method (10) for seeding an optical transmitter. The optical system (200,400) comprises a first optical transmitter (208,408) comprising a first reflective optical amplifier (210,410) and a second optical transmitter (222,422) comprising a second reflective optical amplifier (224,424). The second optical transmitter (222,422) is optically coupled to the first optical transmitter (208,408). The optical system (200,400) also comprises an optical cavity for seeding the first reflective optical amplifier (210,410) with a first optical seed signal. The optical cavity is formed between the first reflective optical amplifier (210,410) of the first optical transmitter (208,408) and the second reflective optical amplifier (224,424) of the second optical transmitter (222,422). The first reflective optical amplifier (210,410) is configured to transmit a first optical signal to the second reflective optical amplifier (224,424) and the second reflective optical amplifier (224,424) is configured to provide the first optical seed signal by reflecting a portion of the first optical signal back to the first reflective optical amplifier (210,410).