Laser Device Optical Pumping Efficiency via Microlens Array

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Solution Overview

Problem

Conventional laser devices face challenges in achieving high pumping efficiency due to low beam quality and inefficient light distribution, which affects the excitation of laser crystals in applications like ignition systems.

Innovation Solution

The laser device incorporates a surface emitting laser array with a microlens array and a condenser lens system to collimate and concentrate light, combined with an optical fiber and a second condensing optical system, ensuring high beam quality and efficient light transmission to a Q-switched laser resonator, comprising a composite Nd:YAG and Cr:YAG crystal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional laser devices use simple optical pumping without advanced optical systems, then the device complexity is low, but the pumping efficiency and beam quality are poor

Engineering Contradiction:
Improvepumping efficiencyVSAvoidoptical system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The optical system is segmented into multiple functional components: a microlens array for collimating light from individual laser elements, optical fibers for light transmission, and a condensing lens for focusing light onto the laser crystal. This segmentation allows each component to optimize its function, achieving high pumping efficiency while managing complexity through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a nested optical configuration where microlenses are positioned within or near the laser elements, optical fibers are coupled to the microlens array output, and the condensing lens is positioned to receive light from the optical fibers. This nested arrangement compactly integrates multiple optical functions in a coordinated manner, improving energy utilization without excessive complexity

Inventive Principle:
Principle #7Nested doll (Nesting)

2Illumination intensity

If light from surface emitting lasers is directly used without collimation and condensation, then the optical system is simple, but the beam quality and energy density are insufficient for effective laser excitation

Engineering Contradiction:
Improvebeam quality and energy densityVSAvoidoptical element complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The microlens array performs preliminary collimation of light emitted from surface-emitting laser elements before the light enters the optical fibers. This preliminary action ensures that light is properly conditioned for efficient coupling into the fibers, maintaining high beam quality throughout the optical path and enabling effective excitation of the laser crystal

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Optical fibers serve as intermediaries that transmit collimated light from the microlens array to the condensing lens. This intermediary component protects and guides the light transmission, maintaining beam quality while allowing flexible positioning of optical components and enabling efficient energy delivery to the laser crystal

Inventive Principle:
Principle #24Intermediary (Mediator)

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 achieves high excitation efficiency and stable Q-switched laser characteristics, enabling efficient and reliable ignition systems with improved energy density and reduced heat generation.

Implementation Method 1

an optical system including a microlens array and a condenser lens system, the microlens array collimating light emitted from the surface emitting laser array

Methodology Applied
Scientific EffectCollimation: Lens

Implementation Method 2

the condenser lens system condensing the light collimated by the microlens array onto a core of the optical fiber

Methodology Applied
Scientific EffectCondensation: Lens

Implementation Method 3

transmission member configured to transmit the light condensed by the condenser lens system to the Q-switched laser resonator

Methodology Applied
Scientific EffectLight transmission: Optical Fibre

Implementation Method 4

a Q-switched laser resonator comprising a laser medium including a composite Nd:YAG and Cr:YAG crystal

Methodology Applied
Scientific EffectOptical pumping: Absorption (EM radiation)

Data Source

PatentEP3002834B1Laser device, ignition system, and internal combustion engine
Publication Date: 2019.09.25 RICOH CO LTD
  • EP3002834B1 patent drawingFigure 1
  • EP3002834B1 patent drawingFigure 2
  • EP3002834B1 patent drawingFigure 3

AI summary

A laser device (200) is provided including a surface emitting laser (201) configured to emit light, an optical system (203) disposed in an optical path of light that is emitted from the surface emitting laser (201), a laser resonator (206) which the light passed through the optical system (203) enters, where the optical system (203) includes a first optical element (203a) configured to collimate the light emitted from the surface emitting laser (201), and a second optical element (203b) configured to collect and condense the light collimated by the first optical element (203a).