Non-classical Light Generation via Modal Phase Matching

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Solution Overview

Problem

Current methods for generating non-classical light using lithium niobate on insulator (LNOI) waveguides with quasi-phase matching (QPM) face challenges such as complexity in manufacture, sensitivity to fabrication imperfections, and limitations in tuning options, particularly in cryogenic environments, where temperature tuning is slow and may affect nearby optical circuitry.

Innovation Solution

The method involves converting classical light into non-classical light by using a non-fundamental propagation mode in the waveguide, eliminating the need for periodic poling and allowing for modal phase matching, which simplifies manufacture and enables electro-optic or piezo-optic tuning, suitable for cryogenic operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If quasi-phase matching (QPM) with periodically poled lithium niobate is used to generate non-classical light, then the generation efficiency is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvenon-classical light generation efficiencyVSAvoidwaveguide structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the periodic poling structure from the lithium niobate waveguide, replacing it with a uniformly poled structure. This removes the complex alternating polarity regions while maintaining the nonlinear optical properties needed for efficient non-classical light generation through spontaneous parametric down-conversion.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the poling parameter from periodic (alternating polarity) to uniform (constant polarity along the waveguide). This parameter change simplifies the manufacturing process and reduces device complexity while still enabling efficient photon pair generation through the nonlinear optical effect in the lithium niobate material.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If periodically poled lithium niobate waveguides are used for non-classical light generation, then conversion efficiency is improved, but sensitivity to fabrication imperfections increases

Engineering Contradiction:
Improvephoton pair generation efficiencyVSAvoidfabrication tolerance
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent removes the periodic poling structure that creates sensitivity to fabrication errors. By using a uniformly poled waveguide instead of periodically poled, the system eliminates the critical dependence on precise periodicity, thereby reducing sensitivity to variations in waveguide geometry and poling accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The uniformly poled structure acts as a cushion against fabrication imperfections by providing a more robust design that does not rely on precise periodic features. The uniform structure inherently tolerates variations in waveguide dimensions and poling depth without significantly degrading the photon pair generation efficiency.

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

3Adaptability or versatility

If temperature tuning is used to adjust the non-classical light source, then wavelength tuning is achieved, but the tuning speed decreases and heat dissipation issues arise

Engineering Contradiction:
Improvewavelength tuning capabilityVSAvoidtuning response time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces the thermal tuning mechanism with electro-optic tuning using lithium niobate's electro-optic effect. This substitution eliminates the need for heat-based wavelength adjustment, enabling fast electrical control of the resonator's optical properties and achieving rapid wavelength tuning without thermal inertia or heat dissipation problems.

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

Solution Approach 2:

The patent changes the tuning parameter from temperature (thermal) to electric field (electrical). By applying voltage to the lithium niobate waveguide, the refractive index and resonant wavelength can be rapidly adjusted through the electro-optic effect, providing fast tuning response times suitable for dynamic applications.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If periodically poled lithium niobate is used for non-classical light generation, then generation efficiency is improved, but integration with optical switches becomes more difficult

Engineering Contradiction:
Improvenon-classical light generation efficiencyVSAvoidintegration compatibility
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent extracts and removes the periodic poling structure that creates incompatibility with optical switch integration. By using uniformly poled lithium niobate, the system eliminates the manufacturing conflicts between QPM waveguides and optical switches, enabling both functions to be integrated on the same chip without requiring different material layers or complex fabrication sequences.

Inventive Principle:
Principle #2Taking out (Extraction)

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 simplifies the manufacture of non-classical light generation devices, reduces sensitivity to fabrication errors, and allows for efficient conversion of classical light into non-classical light, particularly suitable for cryogenic applications by using modal phase matching and non-doped nonlinear optical materials.

Implementation Method 1

converting classical light into non-classical light by using a non-fundamental propagation mode in the waveguide

Methodology Applied
Scientific EffectSpontaneous parametric down-conversion:

Implementation Method 2

allowing for modal phase matching, which simplifies manufacture and enables electro-optic or piezo-optic tuning

Methodology Applied
Scientific EffectModal phase matching:

Implementation Method 3

enables electro-optic or piezo-optic tuning, suitable for cryogenic operations

Methodology Applied
Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 4

enables electro-optic or piezo-optic tuning, suitable for cryogenic operations

Methodology Applied
Scientific EffectPiezo-optic effect:

Data Source

PatentEP4474888A1Method for generating non-classical light from classical light
Publication Date: 2024.12.11 QC DESIGN GMBH
  • EP4474888A1 patent drawingFigure 1~2
  • EP4474888A1 patent drawingFigure 3
  • EP4474888A1 patent drawingFigure 4

AI summary

A method for generating non-classical light from classical light, the method comprising the steps of: providing a non-classical light generation stage (3) comprising at least one waveguide (25), inputting classical light into the non-classical light generation stage (3), and converting in the non-classical light generation stage (3) at least part of the classical light into non-classical light. The classical light is in a non-fundamental propagation mode of a waveguide (25) of the non-classical light generation stage (3) and the non-classical light is in a fundamental propagation mode a waveguide (25) of the non-classical light generation stage (3). The converting does not involve quasi-phase-matching. The method further comprises the step of providing an input adaptation stage (2) for obtaining the classical light to be input into the non-classical light generation stage (3), wherein in the input adaptation stage (2) classical light is converted into classical light of a different waveguide propagation mode. And a system comprising a non-classical light generation stage (3) for converting classical light at least partly into non-classical light, and an optical switch and/or an optical phase shifter (38), the non-classical light generation stage (3) and the optical switch and/or optical phase shifter (38) being arranged on a single optical chip.