Integrated Laser Modulator with Resistive Transition Channel

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Solution Overview

Problem

Existing semiconductor laser devices for optical communications, particularly in WDM systems, face challenges in compactness and heat dissipation due to large polarization tee components and high resistance values, which hinder the development of compact, efficient laser sources.

Innovation Solution

A compact semiconductor laser emission device with an integrated light modulator featuring a multilayer waveguide structure on a silicon dioxide support layer, including a laser amplification section, modulation section, and transition section with a resistive channel for independent polarization control and reduced heat dissipation, utilizing III-V semiconductor materials and protonated insulation for electrical insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a polarization tee is used to couple an electro-absorption modulator to a laser source, then the device can associate a DC component with the radiofrequency signal, but the device size becomes large and prohibitive for compact production

Engineering Contradiction:
Improvesignal modulation capabilityVSAvoiddevice size
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The patent merges the laser source and electro-absorption modulator into a single integrated device structure. The waveguide continuously couples the laser amplification section with the modulation section, eliminating the need for external polarization tee components. This integration maintains the signal modulation capability while dramatically reducing the overall device footprint to a compact form factor suitable for integrated photonic circuits.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a transition section as an intermediary structure between the laser amplification section and modulation section. This transition section includes a resistive channel that mediates the optical and electrical coupling between the two sections, enabling seamless integration without requiring large external polarization control components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If an adaptation resistor with a value of 50 ohms is used across the terminals of the electro-absorption modulator, then the device can be properly matched, but heat dissipation increases to 300 mW

Engineering Contradiction:
Improveimpedance matchingVSAvoidheat dissipation
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a resistive channel with specific electrical properties only in the transition section where needed. The resistive channel has a resistance of 1-10 kΩ localized in the transition region, providing the necessary electrical characteristics for impedance matching and mode transition without requiring high-power adaptation resistors that would generate excessive heat in the modulator terminals.

Inventive Principle:
Principle #3Local quality

3Area of stationary object

If the waveguide structure integrates amplification and modulation sections, then the device becomes compact, but the optical mode propagation may be disturbed at the transition between sections

Engineering Contradiction:
Improvedevice sizeVSAvoidoptical mode propagation
Core Design Contradiction:
Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The transition section acts as an intermediary structure that smoothly connects the amplification and modulation sections. It includes a resistive channel that gradually transforms the optical mode profile, preventing abrupt discontinuities that would cause mode distortion. This intermediary structure maintains stable optical mode propagation throughout the integrated device while enabling compact integration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs parameter changes in the waveguide geometry and material properties along the transition section. The waveguide dimensions and refractive index are gradually modified in the transition region to adapt the optical mode from the amplification section configuration to the modulation section configuration, ensuring continuous and stable mode propagation without sudden disruptions.

Inventive Principle:
Principle #35Parameter changes

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

The solution enables a compact, low-power dissipation laser device with adjustable polarization, maintaining optical mode propagation integrity and facilitating production on silicon-on-insulator configurations.

Implementation Method 1

the first doped layer forms a resistive channel in the transition section between the first doped layer of the amplifier section and the first doped layer of the modulation section

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

the electrical insulation is obtained by a protonated insertion zone of the second doped layer

Methodology Applied
Scientific EffectElectrical Insulation: Electrical Resistance

Implementation Method 3

an amplification section (10), the waveguide in the amplification section containing an amplification means corresponding to an active layer (8)

Methodology Applied
Scientific EffectLight Amplification: Laser

Implementation Method 4

a modulation section (12) followed by an extraction area (14) for radiating light of a resonant optical mode out of the device

Methodology Applied
Scientific EffectElectro-absorption: Absorption (EM radiation)

Implementation Method 5

a multilayer waveguide, the waveguide extending along a longitudinal direction of the device

Methodology Applied
Scientific EffectTotal Internal Reflection: Total Internal Reflection

Data Source

PatentEP2816679B1Laser-emission device with built-in light modulator
Publication Date: 2022.09.21 ALCATEL LUCENT SA
  • EP2816679B1 patent drawingFigure 1~2
  • EP2816679B1 patent drawingFigure 3~4
  • EP2816679B1 patent drawingFigure 5~6

AI summary

A laser emission device with an integrated light modulator comprising: a multilayer waveguide including, on a support layer, a first guiding layer, a first doped layer, a second guiding layer of light-amplifying material, and a second doped layer with polarization opposite to the first doped layer; the waveguide including a laser amplification section (50), a light modulation section (52) including an extraction zone for radiating light, an interposed transition section (51) between the laser amplification section and the light modulation section, a first positive electrode for injecting a pumping current into the laser amplification section, a second positive electrode for injecting a modulation signal into the modulation section, a third negative electrode, and a fourth reference electrode.The second doped layer includes electrical insulation located in the transition section to form a resistive channel.