Photonic Crystal Surface-Emitting Laser Optical Path Tuning
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Solution Overview
Problem
Existing methods struggle to manufacture photonic-crystal surface-emitting lasers with high accuracy in controlling oscillation wavelength and emission light characteristics due to difficulties in precisely controlling the optical path length between the photonic crystal layer and the reflection surface, leading to variations in slope efficiency and yield.
Innovation Solution
A method involving crystal growth, spectrometry, and formation of a translucent electrode with a calculated thickness to control interference between direct and reflected diffracted light, ensuring optimal light intensity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical path length is controlled by growing the semiconductor layer with high accuracy, then the oscillation wavelength and emission light characteristics can be controlled, but it is very difficult to achieve the required precision in layer thickness growth
Solution Approach 1:
The patent applies preliminary action by forming the translucent electrode with a specific thickness range (50-200 nm) before final assembly, which preliminarily establishes the optical path length condition. This preliminary structure allows subsequent adjustment and ensures that the interference condition between direct and reflected diffracted light is satisfied, making the final optical path control more achievable.
Solution Approach 2:
The patent changes the parameter approach from directly controlling semiconductor layer thickness (which is difficult) to controlling the translucent electrode thickness (which is more controllable). By adjusting the electrode thickness within 50-200 nm, the optical path length is controlled indirectly, transforming a difficult control parameter into a more manageable one while achieving the same optical interference effect.
2Productivity
If the layer thickness is not precisely controlled, then manufacturing is easier, but the slope efficiency and emission light characteristics vary significantly
Solution Approach 1:
The patent changes the critical parameter from semiconductor layer thickness to translucent electrode thickness. The electrode thickness can be more precisely controlled within 50-200 nm using standard deposition techniques, ensuring consistent optical interference conditions and reliable emission characteristics without sacrificing manufacturing efficiency.
Solution Approach 2:
The translucent electrode serves as an intermediary element that mediates between the semiconductor layer and the external environment. By controlling this intermediary layer's thickness, the patent achieves precise optical path length control and consistent emission characteristics while maintaining ease of manufacture, as the electrode can be deposited with high precision using conventional techniques.
3Reliability
If a reflection surface is added to improve light extraction, then emission characteristics improve, but the interference between direct and reflected diffracted light becomes difficult to control
Solution Approach 1:
The patent changes the control parameter from the complex optical path through multiple semiconductor layers to the simpler electrode thickness parameter. By controlling the electrode thickness within 50-200 nm, the interference condition is satisfied in a more straightforward manner, reducing the complexity of optical path control while maintaining reliable emission characteristics.
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
Achieves high-performance emission light characteristics with high slope efficiency and improved yield by accurately controlling the optical path length through precise layer thickness determination.
Implementation Method 1
light oscillated due to two-dimensional in-plane resonance in a photonic crystal layer is diffracted in a direction perpendicular to the plane
Implementation Method 2
light diffracted in an opposite direction and reflected by a reflection surface
Implementation Method 3
light diffracted from the photonic crystal layer toward the substrate side (direct diffracted light) and light diffracted in an opposite direction and reflected by a reflection surface (reflected diffracted light) interfere with each other
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A method of manufacturing a surface-emitting laser, includes (a) forming a first semiconductor layer including a photonic-crystal (PC) layer, (b) growing, on the first semiconductor layer, an active layer and a second semiconductor layer, (c) performing spectrometry in which a thickness from a surface of the second semiconductor layer to a position where the spectrometry light is reflected by the PC layer is measured, (d) forming a translucent electrode having a thickness calculated based on an optical path length corresponding to the thickness obtained by the spectrometry on the second semiconductor layer, and (e) forming a reflection layer on the translucent electrode, in which the layer thickness of the translucent electrode is determined such that a light intensity of interference light of (i) direct diffracted light radiated from the PC layer and (ii) reflected diffracted light radiated from the PC layer and reflected by the reflection layer is larger than a light intensity of the direct diffracted light.