VCSEL Ring Resonator Spectral Narrowing
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Solution Overview
Problem
VCSELs have a broad spectral bandwidth, making them unsuitable for certain applications, and existing solutions to narrow this bandwidth are complex, costly, and face challenges in efficiently launching light into waveguides due to orthogonal emission and material compatibility issues.
Innovation Solution
A VCSEL-based narrow-spectrum light source is achieved by using a ring resonator with a large free spectral range and a high-index contrast waveguide material system, allowing for monolithic integration and simplified components, reducing the need for additional tuning devices like Mach-Zehnder interferometers and enabling efficient coupling to optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a VCSEL is used to provide surface-normal emission and simplified packaging, then ease of manufacture and packaging are improved, but spectral bandwidth becomes too broad for certain applications
Solution Approach 1:
The patent merges the VCSEL with a ring resonator into a single integrated device. The ring resonator is formed in the same semiconductor layer as the VCSEL, creating a compact combined structure that narrows the spectral bandwidth while preserving the VCSEL's surface-normal emission properties and manufacturing simplicity.
Solution Approach 2:
The patent changes the optical parameters of the VCSEL by introducing a ring resonator with specific geometric parameters (radius, width) and refractive index properties. This modifies the spectral characteristics from broad to narrow bandwidth while maintaining the original VCSEL emission mode.
2Manufacturing precision
If an external Bragg grating is coupled to a VCSEL to narrow spectral bandwidth, then spectral precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of coupling a separate external Bragg grating to the VCSEL, the patent integrates the resonator functionality directly into the VCSEL structure. The ring resonator is formed in the same semiconductor layer, eliminating the need for external components and reducing device complexity while achieving spectral narrowing.
Solution Approach 2:
The ring resonator is nested within the VCSEL structure, with the resonator path formed in the semiconductor layer surrounding or adjacent to the VCSEL active region. This nested configuration allows the resonator to be part of the VCSEL device itself rather than an external addition.
3Manufacturing precision
If a ring resonator with small radius is used to achieve large free spectral range, then spectral selectivity is improved, but waveguide curvature losses increase
Solution Approach 1:
The patent optimizes the geometric parameters of the ring resonator, specifically the radius and width, to achieve the desired free spectral range while minimizing curvature losses. The resonator width is adjusted to balance the competing requirements of compact size and low propagation loss.
Solution Approach 2:
The patent uses a composite structure with the ring resonator formed in a semiconductor layer with specific refractive index properties. The resonator may incorporate different material compositions or layer structures to enhance light confinement and reduce curvature-related losses while maintaining a compact radius.
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 results in a cost-effective, simpler, and more reliable narrow-spectrum light source with reduced spectral bandwidth, improved manufacturing ease, and efficient light coupling, addressing the limitations of existing technologies.
Implementation Method 1
a ring resonator, which receives spectral components from the VCSEL and resonates at a resonant frequency equal to the center frequency of the VCSEL emission spectrum
Data Source
AI summary
An apparatus and method are disclosed for decreasing the spectral bandwidth of a semiconductor laser, such as a vertical cavity surface emitting laser.