Laser Diode Nano Patterns for Single-Mode Wavelength Control
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Solution Overview
Problem
Conventional laser diode fabrication processes are complex due to the need for discontinuous semiconductor layer growth and limited control over wavelength, particularly in achieving single-mode operation with specific wavelength ranges like 400 nm.
Innovation Solution
A laser diode with column-shaped nano patterns is fabricated using a method where nano patterns are formed on the surface of the semiconductor layers after complete growth, allowing continuous layer growth and adjustable wavelength by controlling the cleavage plane angle, utilizing a substrate with conductive-type clad layers and active layers, and employing nano lithography techniques for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discontinuous semiconductor layer growth is used to form concavo-convex portions, then single-mode laser operation is achieved, but fabrication process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the concavo-convex portions on the semiconductor layer surface after complete continuous growth, rather than during the growth process itself. This allows the layer to grow continuously without interruption, then the desired pattern is created in a subsequent processing step, thereby achieving single-mode operation while maintaining continuous growth and simplifying the overall fabrication process
Solution Approach 2:
The patent inverts the conventional approach by not forming concavo-convex portions through discontinuous growth, but rather by creating them through post-growth processing on a continuously grown layer. This inversion of the process sequence resolves the contradiction by achieving the same structural outcome without the complexity of discontinuous growth control
2Manufacturing precision
If conventional fabrication methods are used, then manufacturing process is established, but wavelength control precision is limited
Solution Approach 1:
The patent applies parameter changes by precisely controlling the geometric parameters of the concavo-convex portions (depth, width, spacing, shape) formed on the semiconductor layer surface. By adjusting these parameters, the optical path difference and interference conditions are controlled, enabling precise wavelength selection and single-mode operation while maintaining compatibility with existing fabrication techniques
3Reliability
If concavo-convex portions are formed during layer growth, then single-mode laser is achieved, but growth process interruption occurs
Solution Approach 1:
The patent performs the action of forming concavo-convex portions as a preliminary or subsequent processing step rather than interrupting the growth process. The semiconductor layer grows continuously to completion, and then the concavo-convex portions are formed by etching or other processing methods, ensuring uninterrupted growth while achieving the desired optical mode control
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 approach simplifies the fabrication process, enables continuous semiconductor layer growth, and allows for precise control of the laser wavelength by adjusting the angle of the cleavage mirrors relative to the nano patterns, achieving single-mode operation within the desired wavelength range.
Implementation Method 1
a layer having a periodically concavo-convex portion, e.g., a concavo-convex portion with a stripe shape, formed along an active layer and reflects light on the layer, thereby implementing a single mode laser
Implementation Method 2
a laser diode in which a wavelength of a laser can be changed depending on a direction of a cleavage plane
Data Source
AI summary
A laser diode having nano patterns is disposed on a substrate. A first conductive-type clad layer is disposed on the substrate, and a second conductive-type clad layer is disposed on the first conductive-type clad layer. An active layer is interposed between the first conductive-type clad layer and the second conductive-type clad layer. Column-shaped nano patterns are arranged at a surface of the second conductive-type clad layer to form a laser diode such as a distributed feedback laser diode.