Light Screening Portion for VCSEL Array Noise Reduction
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Solution Overview
Problem
In light emitting element arrays, especially those using VCSELs, leaked light from one element can act as noise for adjacent monitor PDs, degrading the signal-to-noise ratio and making accurate monitoring and automatic power control challenging due to the lack of effective light screening between elements.
Innovation Solution
Incorporating a light screening portion, formed from a semiconductor layer, between the light emitting and light receiving portions of adjacent elements to absorb leaked light and prevent it from reaching the monitor PDs, thereby improving the signal-to-noise ratio and stability of monitoring and power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light emitting elements are arranged in an array without light screening portions, then the device complexity is reduced and manufacturing is easier, but leaked light from one element acts as noise for adjacent monitor PDs, degrading the signal-to-noise ratio and making accurate monitoring difficult
Solution Approach 1:
The invention divides the light emitting element array into isolated units by introducing light screening portions between adjacent elements. This segmentation prevents light from one element from reaching the monitor PD of another element, thereby eliminating cross-element noise interference and improving the signal-to-noise ratio for optical output monitoring.
Solution Approach 2:
The light screening portion acts as an intermediary structure between adjacent light emitting elements. It selectively blocks leaked light from reaching adjacent monitor PDs while allowing the monitor PD to still detect the optical output from its corresponding light emitting portion, thus improving measurement precision without requiring complete isolation of elements.
2Reliability
If light screening portions are added between light emitting elements, then noise interference is reduced and monitoring accuracy is improved, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The light screening portion is merged with the semiconductor layer structure of the light emitting element array. By forming the light screening portion from the same semiconductor material and integrating it into the existing layer structure, the invention reduces manufacturing complexity while still achieving effective light screening to improve monitoring stability.
Solution Approach 2:
The light screening portion serves multiple functions: it blocks leaked light from reaching adjacent monitor PDs, maintains the semiconductor layer continuity, and can be formed using the same manufacturing processes as the active device layers. This multi-functionality reduces the overall manufacturing difficulty despite adding structural complexity.
3Measurement precision
If light screening portions are implemented, then leaked light is blocked and signal-to-noise ratio is enhanced, but the area occupied by each element increases due to the additional screening structures
Solution Approach 1:
The light screening portions are strategically placed only in the regions where leaked light would interfere with adjacent monitor PDs. This localized approach provides effective light screening and improves detection accuracy only where needed, rather than requiring comprehensive screening across the entire element array, thus minimizing the additional area required.
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
The light screening portion effectively reduces noise interference, enhancing the signal-to-noise ratio and stability of optical output monitoring and automatic power control in light emitting element arrays by blocking leaked light, leading to improved detection accuracy and reduced noise impact.
Implementation Method 1
a light screening portion provided between the plural semiconductor stacking structures to screen light directed from the light emitting portion of one of the semiconductor stacking structures to the light receiving portion of another semiconductor stacking structure
Data Source
AI summary
A light emitting element array includes plural semiconductor stacking structures and a light screening portion. The plural semiconductor stacking structures each include a light emitting portion and a light receiving portion that receives light propagated in a lateral direction via a semiconductor layer from the light emitting portion. The light screening portion is provided between the plural semiconductor stacking structures to screen light directed from the light emitting portion of one of the semiconductor stacking structures to the light receiving portion of another semiconductor stacking structure.