Multi-Aperture VCSEL Emitter for High-Power Single-Mode Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing VCSELs face limitations in reducing aperture diameter for high power output due to increased resistance and reduced output power, while maintaining beam coherence and avoiding mode coupling.
Innovation Solution
The method involves etching blind holes into the layer stack to form multiple apertures within a mesa, allowing parallel operation of VCSEL sub-cells, with oxidation occurring from the inside of the holes to create independent apertures, and using conducting material to manage current flow and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the aperture diameter of VCSEL is reduced to achieve narrow emission spectra and suppress higher order modes, then spectral narrowness and mode suppression are improved, but electrical resistance increases and output power drops
Solution Approach 1:
The VCSEL aperture is divided into multiple smaller sub-apertures (e.g., 2x2=4 sub-apertures or 3x3=9 sub-apertures) within a single mesa structure. Each sub-aperture has a diameter of approximately 3-5 µm, which is sufficient to suppress higher order modes and achieve narrow spectral emission. The multiple sub-apertures operate in parallel, collectively providing high output power while maintaining the electrical resistance benefits of smaller aperture dimensions.
2Manufacturing precision
If the aperture diameter of VCSEL is reduced to achieve narrow emission spectra and suppress higher order modes, then spectral narrowness and mode suppression are improved, but electrical resistance increases
Solution Approach 1:
The aperture is segmented into multiple sub-apertures that collectively provide low electrical resistance. The total conductive area is distributed across multiple sub-apertures, each with its own contact region, effectively reducing the overall electrical resistance compared to a single large aperture while maintaining the spectral benefits of small aperture dimensions.
3Power
If multiple apertures are formed within a single mesa, then output power and impedance matching are improved, but fabrication complexity increases
Solution Approach 1:
The multiple sub-apertures are formed within the mesa structure before the final device operation. The oxidation process that creates the aperture boundaries is performed in advance during fabrication, establishing the multi-sub-aperture configuration that will operate in parallel during device operation. This preliminary formation of the multi-aperture structure simplifies subsequent processing steps.
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 enables larger optical output power with smaller apertures, reduced electrical resistance, and single mode emission, supporting long-distance data transmission and dense wavelength multiplexing with improved impedance matching.
Implementation Method 1
an active region (13) in between, which generates optical radiation (P) when electrical current flows through the VCSEL
Implementation Method 2
said apertures (40) are formed (either before the mesa (M) is etched or thereafter) by etching blind holes (30) and oxidizing oxidizable layer or layers (21-24) from the inside of the holes via the holes' sidewalls (31)
Data Source
Figure 1~4
Figure 5~8
Figure 9~12
AI summary
An exemplary embodiment of the invention relates to a method of fabricating a radiation emitter (100) comprising the steps of fabricating a layer stack (10) that comprises a first reflector (12), an active region (13), an oxidizable layer (21-24), and a second reflector (14); and locally removing the layer stack (10), and thereby forming a mesa (M) of the radiation emitter (100), wherein said mesa (M) comprises the first reflector (12), the active region (13), the oxidizable layer (21-24) and the second reflector (14), wherein before or after locally removing the layer stack (10) and forming said mesa (M) the following steps are carried out: vertically etching blind holes (30) inside the layer stack (10), wherein the blind holes (30) vertically extend at least to the oxidizable layer (21-24) and expose the oxidizable layer (21-24); and oxidizing the oxidizable layer (21-24) via the sidewalls (31) of the blind holes (30) in lateral direction, wherein from each hole an oxidation front (32) radially moves outwards and wherein the etching is terminated before the entire oxidizable layer (21-24) is oxidized, thereby forming at least two unoxidized apertures, (40) each of which is limited by at least three oxidation fronts (32), inside the mesa.