External Resonant Laser Module Packaging for Stray Light Suppression
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Solution Overview
Problem
The external resonant laser module faces issues with stray light entering the package, which can mix with the laser light and deteriorate the laser quality.
Innovation Solution
The module incorporates a package design with a lens holder positioned such that the distance between the top wall and the lens holder is smaller than the thickness of the lens holder, effectively suppressing stray light from entering the space where the quantum cascade laser element is located.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional package design with sufficient space between the top wall and lens holder is used, then ease of assembly and manufacturing is improved, but stray light can enter the space between the top wall and lens holder and mix with laser light, deteriorating laser quality
Solution Approach 1:
The patent applies dimensional constraint by reducing the gap distance between the top wall and lens holder to a specific range (0.1-2.0 mm), transforming the spatial relationship from a conventional larger gap to a tightly controlled minimal gap. This dimensional change effectively blocks stray light paths while maintaining manufacturability through precise positioning features.
Solution Approach 2:
The patent changes the critical parameter of gap distance between the top wall and lens holder from a conventional larger value to a specifically controlled small value (0.1-2.0 mm). This parameter change directly addresses the stray light issue by eliminating sufficient space for stray light propagation, while the invention provides methods to achieve this tight tolerance through precision machining and positioning features.
2Reliability
If the distance between the top wall and lens holder is reduced to suppress stray light, then laser quality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-establishing the precise positional relationship between the lens holder and top wall through dedicated positioning features (such as positioning holes, ribs, or chamfers) during assembly. This preliminary positioning ensures that the gap distance is controlled within the required 0.1-2.0 mm range, reducing the burden on final assembly operations and ensuring consistent stray light suppression.
Solution Approach 2:
The patent introduces intermediary positioning features (such as positioning holes, ribs, or chamfers) that mediate between the top wall and lens holder to maintain the critical gap distance. These intermediary elements serve as mechanical mediators that automatically establish and maintain the precise 0.1-2.0 mm spacing, transforming a difficult direct spacing control problem into a more manageable feature-based positioning problem.
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 effectively prevents stray light from mixing with the laser light, thereby ensuring improved laser quality and security.
Implementation Method 1
a lens for passing an outgoing light from the quantum cascade laser element and a light returned from the movable diffraction grating to the quantum cascade laser element
Implementation Method 2
light from the quantum cascade laser element is diffracted and reflected by the diffraction grating, and light having a specific wavelength among the light from the quantum cascade laser element is returned to the quantum cascade laser element
Implementation Method 3
An external resonant laser module including a quantum cascade laser element
Data Source
AI summary
The laser module includes a QCL element, a MEMS diffraction grating, a lens holder for holding a lens disposed between the QCL element and the MEMS diffraction grating, and a package. The package includes a bottom wall, a side wall erected on the bottom wall and formed in an annular shape so as to surround a region in which the QCL element is accommodated, and a top wall closing an opening of the side wall on a side opposite to a side where the bottom wall is disposed. The top wall faces the bottom wall in a direction orthogonal to the optical axis direction of the lens, and the distance between the top wall and a surface of the lens holder on a side where the top wall is disposed is smaller than a thickness of the lens holder along the optical axis direction of the lens.