VCSEL Polarization-Selective Hybrid Layer for Low Diffraction Loss
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Solution Overview
Problem
Conventional vertical cavity surface emitting lasers (VCSELs) face challenges in achieving stable polarization due to manufacturing complexities and high production costs, particularly with diffraction gratings and subwavelength gratings, which result in performance reductions and increased costs.
Innovation Solution
A vertical cavity surface emitting laser design that integrates a near wavelength grating layer with a second reflector layer, where the grating period is smaller than the wavelength in the propagating medium but larger than in the semiconductor material, forming a polarization selective hybrid layer, simplifying structure and reducing costs by eliminating higher order diffraction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If diffraction gratings with period larger than wavelength are used, then fabrication is straightforward, but higher order diffraction losses cause significant performance reduction
Solution Approach 1:
The patent changes the grating period parameter to be smaller than the wavelength of light, which fundamentally alters the diffraction behavior. This parameter change eliminates higher order diffraction losses while maintaining polarization stabilization functionality, resolving the contradiction between fabrication ease and energy loss.
Solution Approach 2:
The patent creates a composite structure by integrating the grating layer with the semiconductor active layer. This composite approach allows the grating to be formed within the semiconductor material system, simplifying fabrication while achieving the desired optical properties that reduce diffraction losses.
2Reliability
If subwavelength gratings with period smaller than wavelength are used, then polarization stabilization is achieved, but manufacturing complexity and production cost increase hugely
Solution Approach 1:
The patent merges the grating structure with the semiconductor active layer, forming an integrated composite structure. This combining approach achieves subwavelength grating functionality for polarization stabilization while using conventional semiconductor fabrication processes, greatly reducing manufacturing complexity and cost.
Solution Approach 2:
The grating structure is formed by copying patterns directly into the semiconductor material using standard lithography and etching processes. This copying approach enables precise subwavelength feature fabrication using conventional manufacturing tools, avoiding the need for specialized processes.
3Reliability
If subwavelength gratings are formed based on special epitaxy, then polarization stabilization is achieved, but production cost increases
Solution Approach 1:
The patent designs a grating structure that can be fabricated using universal semiconductor manufacturing processes that are already widely deployed. This multi-functional approach allows the same fabrication infrastructure to produce both standard VCSELs and polarization-stabilized VCSELs, eliminating the need for special epitaxy processes and reducing production costs.
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 design enables highly stable and polarized laser light emission, reduces production costs, and maintains performance by minimizing diffraction losses, making the VCSELs simpler to fabricate and integrate with conventional devices.
Implementation Method 1
a near wavelength grating layer 152 integrated above the second reflector layer 151, where a period of a near wavelength grating is smaller than a wavelength of light in a propagating medium
Implementation Method 2
forming a polarization selective hybrid layer of a laser cavity, so that highly stable and highly polarized laser light can be emitted
Data Source
Figure 1~2(c)
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AI summary
The present disclosure provides a vertical cavity surface emitting laser, relating to the technical field of photoelectric devices. The vertical cavity surface emitting laser includes a substrate layer, a buffer layer, a first reflector layer, a light emitting layer, a polarization selective hybrid layer and an electrode layer that are stacked. The polarization selective hybrid layer includes a second reflector layer and a near wavelength grating layer integrated above the second reflector layer, where a period of a near wavelength grating is smaller than a wavelength of light in a propagating medium and larger than a wavelength of light in a semiconductor material of the vertical cavity surface emitting laser. The vertical cavity surface emitting laser can emit highly stable and highly polarized laser light, and is simple in structure and convenient to fabricate. The second reflector layer is thinner, which reduces the production cost.