VCSEL Diffuser Integration With Monitor Photodetector Feedback
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Solution Overview
Problem
Existing light sources with integrated diffusers face challenges in package-level integration and associated costs, particularly when trying to achieve uniform light profiles for specific illumination functions.
Innovation Solution
A light source configuration that integrates a VCSEL, a monitor photodetector, and a diffuser on the same substrate, allowing for chip-level integration and real-time monitoring of the diffuser's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffuser is integrated at the package level away from the optical source, then uniform light profiles can be achieved, but integration complexity and costs increase
Solution Approach 1:
The patent merges the diffuser and monitor photodetector directly onto the VCSEL chip substrate, eliminating the need for separate package-level integration. The diffuser is positioned on the substrate and the monitor photodetector is integrated in close proximity, creating a compact monolithic structure that reduces integration complexity while maintaining uniform light profile capability
Solution Approach 2:
The patent transitions from planar/package-level integration to three-dimensional vertical stacking on the chip substrate. The VCSEL, diffuser, and monitor photodetector are arranged in vertical layers, allowing compact integration without increasing lateral footprint and reducing package complexity
2Illumination intensity
If a diffuser is integrated at the package level, then light diffusion can be achieved, but manufacturing costs increase
Solution Approach 1:
The patent combines multiple functions (light generation, diffusion, and monitoring) into a single integrated chip structure, eliminating the need for separate package-level assembly of diffusers and reducing manufacturing steps, materials, and associated costs
Solution Approach 2:
The monitor photodetector integrated on the same chip automatically monitors the diffuser's performance and provides feedback for real-time adjustments, enabling self-diagnosis and quality control without additional external testing equipment or manual inspection processes
3Reliability
If a monitor photodetector is integrated to receive reflected optical signal, then real-time monitoring capability is achieved, but device complexity increases
Solution Approach 1:
The monitor photodetector is positioned to receive light that has reflected off the diffuser at a specific angle, utilizing the third dimension (vertical/z-axis) for light path separation. This spatial arrangement allows monitoring functionality to be added without requiring complex lateral routing or additional planar space on the chip
4Illumination intensity
If the diffuser is positioned on the substrate opposite the VCSEL, then uniform light distribution is achieved, but eye safety monitoring becomes more difficult
Solution Approach 1:
The monitor photodetector continuously measures the reflected optical signal from the diffuser and provides real-time feedback about diffuser performance and potential failures. This feedback mechanism enables automatic safety shutdown or warning systems to protect against eye damage from malfunctioning diffusers
Solution Approach 2:
The reflected optical signal serves as an intermediary carrier that conveys information about diffuser health and performance back to the monitor photodetector. By monitoring this reflected signal, the system can detect diffuser failures that might otherwise go unnoticed and pose eye safety risks
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 configuration enables cost-effective, high-reliability light sources with uniform light profiles, while also allowing for real-time monitoring and control of the diffuser's operation, enhancing eye safety and system performance.
Implementation Method 1
at least one light generator in the epitaxial layer positioned such that an optical signal transmitted is directed toward the substrate
Implementation Method 2
A diffuser may control divergence of the profile of the light source
Implementation Method 3
receive a portion of the optical signal which is reflected by the diffuser
Implementation Method 4
at least one monitor photodetector in the epitaxial layer is positioned to receive a portion of the optical signal which is reflected by the diffuser
Data Source
AI summary
A light source includes a substrate with a first surface and an opposite second surface. An epitaxial layer is positioned on the first surface of the substrate. The light source also includes at least one light generator in the epitaxial layer positioned such that an optical signal transmitted thereby is directed toward the substrate. A diffuser is positioned on the second surface of the substrate, and at least one monitor photodetector is positioned in the epitaxial layer in an arrangement configured to receive a portion of the optical signal which is reflected by the diffuser. In one form, the light generator may include a vertical cavity surface emitting laser (VCSEL).