VCSEL Optical Mode Control via Aperture Segmentation
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Solution Overview
Problem
Existing surface emitting semiconductor lasers, particularly VCSELs, face challenges in accurately controlling the laser mode and achieving single-mode operation due to difficulties in precisely controlling the diameter of the current confining layer, leading to reduced yield and efficiency in optical communication applications.
Innovation Solution
The implementation of an optical mode controlling layer between the reflective mirrors, which includes a selectively formed opening to absorb or reflect light, allowing for precise control of the lasing mode by adjusting the diameter of this opening, thereby achieving single-mode operation and improving mode control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the diameter of the current confining layer is reduced to 3-4 micrometers to obtain single-mode operation, then the laser mode control is improved, but the manufacturing precision deteriorates due to difficulty in accurately controlling the oxidized aperture diameter
Solution Approach 1:
The patent divides the mode control function into two separate components: the current confining layer (which confines the current) and the optical mode controlling layer (which controls the light mode). This segmentation allows each layer to be optimized independently - the current confining layer can be made with precise diameter control through oxidation, while the optical mode controlling layer with its opening is specifically designed to control the laser mode and achieve single-mode operation.
Solution Approach 2:
The optical mode controlling layer acts as an intermediary component between the current confining layer and the active layer. It mediates the optical field distribution by selectively absorbing or reflecting light, thereby controlling the laser mode without directly affecting the current confinement mechanism. This intermediary structure enables precise mode control while maintaining the integrity of the current confining layer.
2Reliability
If the diameter of the current confining layer is reduced to achieve single-mode, then the laser performance is improved, but the ease of manufacture deteriorates due to difficulty in reproducing small aperture diameter
Solution Approach 1:
The patent separates the current confinement function from the optical mode control function into distinct layers. The current confining layer maintains its oxidation-based fabrication process for current confinement, while the optical mode controlling layer with its opening is specifically engineered to control the optical mode. This segmentation allows each layer to be manufactured using processes optimized for its specific function, improving overall ease of manufacture.
Solution Approach 2:
The patent changes the approach to mode control by introducing a new parameter - the opening diameter in the optical mode controlling layer - which can be independently optimized for single-mode operation. This parameter can be precisely controlled during fabrication without being constrained by the oxidation process limitations that affect the current confining layer, thereby improving ease of manufacture for achieving single-mode operation.
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 solution enables effective control of lasing modes, including transverse and polarization modes, and allows for the selection of desired oscillation wavelengths, enhancing the performance and yield of surface emitting semiconductor lasers in optical communication systems.
Implementation Method 1
an opening is formed for selectively absorbing or reflecting off light that is emitted in the active layer
Implementation Method 2
an opening is formed for selectively absorbing or reflecting off light that is emitted in the active layer
Data Source
AI summary
A surface emitting semiconductor laser includes a substrate, a lower reflective mirror formed on the substrate, an active layer formed on the lower reflective mirror, an upper reflective mirror formed on the active layer, an optical mode controlling layer formed between the lower reflective mirror and the upper reflective mirror, and a current confining layer formed between the lower reflective mirror and the upper reflective mirror. The active layer emits light. The upper reflective mirror forms a resonator between the lower reflective mirror and the upper reflective mirror. In the optical mode controlling layer, an opening is formed for selectively absorbing or reflecting off light that is emitted in the active layer. The optical mode controlling layer optically controls mode of laser light. The current confining layer confines current that is applied during driving.