Tilted Void Photonic Crystal for Stable Single-Mode Surface Emission Laser
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Solution Overview
Problem
Current surface emission lasers with photonic crystals face challenges in achieving high resonance and stable single lateral mode operation, particularly at high output levels, due to limitations in diffraction effects and optical confinement factors.
Innovation Solution
A surface emission laser design featuring a group III nitride semiconductor structure with periodically arranged voids in a square lattice pattern, where the voids have a polygonal prism or oval columnar shape, and are inclined at specific angles to enhance two-dimensional coupling coefficients, thereby increasing the optical confinement factor and reducing high-order transverse modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photonic crystal structures are used, then manufacturing is simpler, but diffraction effect and optical confinement factor are insufficient
Solution Approach 1:
The patent applies asymmetry by tilting the voids at a specific angle (e.g., 45 degrees) relative to the square lattice arrangement. This asymmetric configuration breaks the symmetry of conventional photonic crystals, enhancing the diffraction effect and optical confinement factor while maintaining manufacturability through standard fabrication processes.
Solution Approach 2:
The patent introduces a new dimensional parameter by tilting the voids in three-dimensional space rather than arranging them purely in two-dimensional planes. This angular dimension (θ) adds a degree of freedom to the photonic crystal structure, enabling enhanced optical confinement and diffraction effects without increasing lateral complexity.
2Reliability
If photonic crystal parameters are optimized for high diffraction effect, then beam quality improves, but achieving stable single lateral mode operation at high output becomes difficult
Solution Approach 1:
The asymmetric void arrangement creates an optical potential landscape that preferentially supports fundamental modes while suppressing higher-order modes. The tilted configuration produces different effective refractive indices for different mode families, creating a larger mode spacing that stabilizes single-mode operation even at high output powers.
Solution Approach 2:
The patent optimizes specific parameters including the tilt angle (θ), void radius (r), and lattice constant (a) to achieve the desired balance between diffraction effect and mode stability. By carefully adjusting these parameters, the photonic crystal provides strong optical confinement for the fundamental mode while creating conditions that suppress high-order transverse modes at high power levels.
3Productivity
If voids are arranged in square lattice with specific inclination, then diffraction effect is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs periodic arrangement of tilted voids in a square lattice pattern. This periodic structure can be fabricated using standard photolithography and etching processes with periodic masks, allowing for controlled lateral growth speeds while maintaining the required arrangement precision through repeatable manufacturing cycles.
Solution Approach 2:
The asymmetric tilt angle provides a clear geometric feature that can be easily defined during fabrication. The tilt creates distinct sidewall angles that are robust to manufacturing variations, making the structure less sensitive to minor deviations in void placement while still achieving the desired optical performance.
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 design achieves a stable single lateral mode operation with high beam quality even at high output levels, by optimizing the diffraction effect and optical confinement, resulting in improved performance and reduced high-order transverse modes.
Implementation Method 1
enhancing a diffraction effect in a photonic crystal layer is required
Implementation Method 2
a surface emission laser using a photonic crystal
Data Source
AI summary
A surface emission laser formed of a group III nitride semiconductor includes a first conductivity type first clad layer; a first conductivity type first guide layer on the first clad layer; a light-emitting layer on the first guide layer; a second guide layer on the light-emitting layer; and a second conductivity type second clad layer on the second guide layer. The first or second guide layer internally includes voids periodically arranged at square lattice positions with two axes perpendicular to one another as arrangement directions in a surface parallel to the guide layer. The voids have a polygonal prism structure or an oval columnar structure with a long axis and a short axis perpendicular to the long axis in the parallel surface, and the long axis is inclined with respect to one axis among the arrangement directions of the voids.