Optical Module Laser Switching for Thermal Protection

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Solution Overview

Problem

Current photonic technologies for radio base stations face challenges with low energy efficiency, high frequency-dependent channel loss, and complex equalization circuits due to the integration of internal lasers in optical transceivers, which also pose issues with thermal management and serviceability.

Innovation Solution

The proposed solution involves an optical module with internal lasers and an external laser source, where a controller monitors the temperature of internal lasers and switches to an external optical signal when thermal stress is detected, reducing the operating power of internal lasers and maintaining optical power consistency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If internal lasers are integrated into the optical transceiver, then device integration and cost are improved, but thermal management becomes difficult and laser lifetime decreases

Engineering Contradiction:
Improvedevice integrationVSAvoidthermal management
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The system segments the laser function into internal lasers for normal operation and external lasers for thermal protection, allowing the internal lasers to be integrated for cost efficiency while external lasers handle thermal management challenges

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

External lasers are prepared in advance as backup sources that can be activated when thermal stress is detected, cushioning against potential damage to internal lasers from thermal runaway

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If internal lasers are integrated into the optical transceiver, then device integration is improved, but laser serviceability and reliability worsen

Engineering Contradiction:
Improvedevice integrationVSAvoidlaser serviceability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The laser system is segmented into replaceable external laser modules and fixed internal lasers, allowing the external modules to be serviced independently while maintaining the integrated design benefits

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

External laser modules can be discarded and replaced when failed, while internal lasers are protected from failure through thermal management, recovering system functionality without replacing the entire integrated transceiver

Inventive Principle:
Principle #34Discarding and recovering

3Power

If internal lasers operate at high power, then optical signal quality is improved, but thermal stress increases and may cause laser failure

Engineering Contradiction:
Improveoptical signal qualityVSAvoidlaser failure risk
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The system dynamically switches between internal and external lasers based on thermal conditions, allowing internal lasers to operate at high power when cool and transitioning to external lasers when thermal stress becomes critical

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Temperature sensors provide feedback on internal laser thermal conditions, triggering activation of external lasers when thermal thresholds are exceeded, creating a closed-loop thermal management system

Inventive Principle:
Principle #23Feedback

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 approach effectively mitigates thermal stress and extends the operating lifetime of internal lasers, while maintaining performance and reducing costs by utilizing cost-effective internal lasers for most operations and external lasers only when needed.

Implementation Method 1

a temperature sensor arranged to sense a temperature of the internal lasers and to generate a temperature reporting signal

Methodology Applied
Scientific EffectTemperature sensing: Thermocouple

Implementation Method 2

optical modulators arranged to modulate optical signals

Methodology Applied
Scientific EffectOptical modulation: Electro-Optic Effects

Data Source

PatentEP4381630B1Communications network optical apparatus and method of providing an optical signal
Publication Date: 2025.05.28 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4381630B1 patent drawingFigure 1
  • EP4381630B1 patent drawingFigure 2
  • EP4381630B1 patent drawingFigure 3

AI summary

Communications network optical apparatus (100) comprising an optical module (120) and a controller (140). The optical module (120) comprises optical modulators (122), internal lasers (124) to generate internal optical signals, an input port (126) to receive an external optical signal from an external laser, optical routing devices (128) to route internal optical signals from internal lasers to optical modulators and to route an external optical signal from the input port to at least one of the optical modulators. and a temperature sensor (130) to sense a temperature of the internal lasers and to generate a temperature reporting signal. The controller (140) comprises processing circuitry (142) and memory (144) containing instructions which when executed by the processing circuitry cause the controller to perform operations including receiving the temperature reporting signal, determining that a thermal protection condition exists based on the temperature of the internal lasers, and in response to the determining, generating control signals configured to cause the external optical signal to be provided to at least one optical modulator and to cause an operating power of at least one respective internal laser to be reduced.