Photonic Circuit Optical Temperature Sensing for Component Hotspots

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Solution Overview

Problem

Existing temperature measurement methods for photonic integrated circuits (PICs) are inadequate, as conventional electronic sensors face spatial constraints and electrical interference issues, leading to inaccurate temperature readings across individual components, which can cause thermal instability and reduced operating lifetimes.

Innovation Solution

Implementing optical temperature sensors within the PIC, utilizing temperature-dependent spectral shifts in components like Mach-Zehnder interferometers or electro-absorption modulators to measure temperature without interfering electrically, allowing for precise temperature monitoring of individual photonic components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional electronic temperature sensors (RTDs) are used to measure temperature of photonic components, then temperature measurement capability is provided, but spatial constraints and electrical interference prevent accurate placement near photonic components

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidsensor placement feasibility
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces conventional electronic temperature sensors (RTDs) with optical temperature sensors that use light instead of electrical signals. This substitution eliminates electrical interference with photonic components while maintaining the ability to measure temperature accurately near the photonic devices.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary (light) as the medium for temperature sensing. By using optical signals rather than direct electrical contact, the system can measure temperature near photonic components without the electrical interference that plagues conventional electronic sensors.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If temperature measurements are taken of the entire PIC, then overall thermal status is obtained, but spatial variation in temperature across the PIC makes these measurements inadequate for component-level thermal design

Engineering Contradiction:
Improvecomponent-level temperature measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the temperature measurement function into multiple independent optical sensors positioned at different locations within the PIC. Each sensor measures the temperature of specific photonic components independently, allowing for spatially-resolved temperature mapping without requiring a single complex measurement system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements temperature sensing with local quality by placing optical sensors in close proximity to specific photonic components that require temperature monitoring. This allows each sensor to provide accurate temperature data for its local region, capturing the spatial variations in temperature across the PIC.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If optical temperature sensors are placed in close proximity to diode junctions, then accurate component temperature measurement is achieved, but spatial constraints in the compound semiconductor layer make placement difficult

Engineering Contradiction:
Improvediode junction temperature measurement accuracyVSAvoidavailable space for sensor placement
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent moves the optical temperature sensors from the compound semiconductor layer to the silicon device layer underneath the active devices. This dimensional relocation provides available space for sensor placement while maintaining optical coupling to the diode junctions through the substrate, thereby achieving accurate temperature measurement without spatial constraints.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 accurate temperature measurement of photonic components, reducing thermal cross-talk and hotspot issues, thereby extending operating lifetimes and improving thermal design by minimizing heating effects.

Implementation Method 1

utilizing temperature-dependent spectral shifts in components like Mach-Zehnder interferometers or electro-absorption modulators to measure temperature

Methodology Applied
Scientific EffectTemperature-dependent spectral shift:

Data Source

PatentEP3978975B1Optical temperature measurements in photonic circuits
Publication Date: 2024.10.30 OPENLIGHT PHOTONICS INC
  • EP3978975B1 patent drawingFigure 1
  • EP3978975B1 patent drawingFigure 2
  • EP3978975B1 patent drawingFigure 3A~3B

AI summary

Temperature measurements of photonic circuit components may be performed optically, exploiting a temperature-dependent spectral property of the photonic device to be monitored itself, or of a separate optical temperature sensor placed in its vicinity. By facilitating measurements of the temperature of the individual photonic devices rather than merely the photonic circuit at large, such optical temperature measurements can provide more accurate temperature information and help improve thermal design.