Talbot Cavity Array Laser Phase Synchronization

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Solution Overview

Problem

Conventional array type wavelength converting laser devices suffer from poor light focusing power due to independent phase oscillations of laser light rays from individual emitting points, leading to increased beam size and reduced focusing efficiency of second harmonics.

Innovation Solution

The device incorporates a Talbot cavity configuration where the wavelength converting element is positioned between the laser element and output mirror, with the distance between the laser element's waist and output mirror set to achieve phase synchronization between adjacent light emitting points, ensuring optimal phase alignment and focusing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the array type wavelength converting laser device oscillates laser light rays independently from individual light emitting points, then multiple oscillations in spatial mode can be achieved, but the phases of laser light rays lack correlation between light emitting points, leading to increased beam size and deteriorated light focusing power

Engineering Contradiction:
Improvemultiple oscillations in spatial modeVSAvoidlight focusing power
Core Design Contradiction:
Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent introduces a feedback mechanism where the optical path from each light emitting point is reflected back through the same path by mirrors, creating a resonant cavity that enforces phase correlation. The light travels from each emitting point through the nonlinear crystal, reflects off the output mirror, and returns through the same path, providing feedback that synchronizes phases across all emitting points while maintaining spatial mode oscillations

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent adds a temporal dimension to the spatial array by creating a resonant optical path that extends the interaction time of light with each emitting point. By forming a cavity that supports standing waves, the system transforms independent spatial oscillations into correlated spatiotemporal modes, where phase relationships are established through the round-trip optical path

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

2Ease of operation

If a focusing lens is arranged outside the cavity to focus the light, then the laser light rays are focused, but the beam size increases due to lack of phase correlation, and the light focusing power of second harmonics is deteriorated

Engineering Contradiction:
Improvelight focusing capabilityVSAvoidbeam size and focusing efficiency
Core Design Contradiction:
Ease of operationVSIllumination intensity

Solution Approach 1:

The patent performs preliminary phase alignment by designing the cavity geometry and optical path lengths such that phases are synchronized before the light exits the cavity. The mirrors and optical paths are configured to pre-establish phase correlations, so that when light exits and passes through the focusing lens, it maintains correlated phases that enable tight focusing without beam divergence

Inventive Principle:
Principle #10Preliminary action

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 significantly improves the light focusing power of the laser light, reducing beam size and enhancing the efficiency of wavelength conversion, resulting in a more focused and intense output.

Implementation Method 1

a wavelength converting element 1003 for carrying out wavelength conversion of the fundamental waves to output second harmonics

Methodology Applied
Scientific EffectSecond Harmonic Generation: Second Harmonic Generation

Implementation Method 2

The laser medium creates a thermal lens effect with an effect equal to aligning a plurality of lenses in the array direction owing to the refractive index distribution in the laser medium

Methodology Applied
Scientific EffectThermal lens effect: Lens

Implementation Method 3

an output mirror 1004 for reflecting the fundamental waves and transmitting the second harmonics

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3244498B1Array type wavelength converting laser device
Publication Date: 2019.12.25 MITSUBISHI ELECTRIC CORP
  • EP3244498B1 patent drawingFigure 1
  • EP3244498B1 patent drawingFigure 2A~2E
  • EP3244498B1 patent drawingFigure 3

AI summary

A device includes: at least one laser element (1) with light emitting points to output fundamental waves in a one-dimensional array; a wavelength converting element (2) to carry out wavelength conversion of the incident fundamental waves, and to output wavelength converted light rays; and an output mirror (3) to reflect the fundamental waves, and to transmit the wavelength converted light rays resulting from the wavelength conversion by the wavelength converting element (2). The wavelength converting element (2) is disposed between the laser element (1) and the output mirror (3), and the distance between the position of a waist (103) of the fundamental waves output from the laser element (1) and the output mirror (3) is set in accordance with a Talbot condition under which the adjacent light emitting points cause phase synchronization with each other.