Mesh Grating Reflector for Lightweight Broadband VCSEL Reflection
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Solution Overview
Problem
Existing grating reflectors in wavelength tunable or sweepable vertical cavity surface emitting lasers (VCSELs) face challenges in achieving high polarization-dependent reflectivity across a broad bandwidth while being lightweight and mechanically robust.
Innovation Solution
A grating reflector with a mesh structure comprising parallel bars and crossbars forming a two-dimensional grid of elongated holes with rounded corners, optimized to have a unit cell volume ratio between 1.35 and 1.55 times the center wavelength cubed, ensuring high reflectivity and mechanical stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a grating reflector is made lightweight, then mass is reduced, but mechanical robustness deteriorates
Solution Approach 1:
The grating reflector is segmented into a mesh structure comprising multiple parallel bars and crossbars that form a two-dimensional grid. This segmentation allows the structure to achieve high stiffness-to-mass ratio by distributing mechanical loads across multiple elements while maintaining overall lightness. The mesh configuration provides both weight reduction and structural integrity simultaneously.
Solution Approach 2:
The grating reflector employs a composite structure combining bars and crossbars in a mesh configuration, creating a composite material system that optimizes both mechanical properties and mass. This composite approach allows the structure to exhibit enhanced mechanical robustness while maintaining low mass, resolving the contradiction between lightweight design and structural strength.
2Reliability
If the mesh structure is optimized for high reflectivity, then optical performance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention optimizes specific geometric parameters of the mesh structure, including bar width, crossbar width, hole dimensions, and unit cell volume ratio relative to the center wavelength. By carefully controlling these parameters within specific ranges, high reflectivity is achieved while maintaining manufacturability through standardized design rules that simplify the manufacturing process.
Solution Approach 2:
The mesh structure incorporates rounded corners at the intersections of bars and crossbars, creating local geometric variations that enhance optical performance. This local quality modification at critical locations improves reflectivity and mechanical properties without requiring complex manufacturing processes, as the rounded corners can be achieved through standard fabrication techniques.
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 grating reflector achieves reflectivity higher than 0.99 across a bandwidth of at least 10% of the center wavelength, with improved mechanical robustness and reduced mass, suitable for applications like spectroscopy and optical coherence tomography.
Implementation Method 1
grating reflector comprises a mesh structure... the two dimensional grid being defined by a cross-shaped unit cell... reflectivity in a bandwidth around a center wavelength higher than 0.99
Implementation Method 2
mesh structure comprising a plurality of parallel bars and a plurality of parallel crossbars... bars and crossbars defining a two-dimensional grid of elongated holes
Data Source
AI summary
A grating reflector. The grating reflector includes a mesh structure defining a mesh plane and having a thickness normal thereto. The mesh structure includes parallel bars and parallel crossbars, which extend along a direction orthogonal to the bars. The bars and crossbars define a 2D grid of elongated holes, each extending through the mesh structure perpendicular to the mesh plane. The holes are elongated along a direction parallel to the bars and have a substantially rectangular shape with rounded corners. The 2D grid is defined by a cross-shaped unit cell having a bar section and an intersecting crossbar section. The grating reflector has a reflectivity in a bandwidth around a center wavelength higher than 0.99. A ratio between the unit cell volume and the center wavelength in the mesh material cubed is between 1.35 and 1.55.