VCSEL Common Anode Structure to Limit Reverse Bias and Voltage
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Solution Overview
Problem
Conventional VCSEL arrays with a common cathode structure face issues such as reduced VCSEL lifespan due to inverse voltage application to unselected VCSELs and increased operating voltage requirements to compensate for parasitic inductance.
Innovation Solution
The implementation of a VCSEL and VCSEL array with a common anode structure, featuring an n-type semiconductor substrate, n-type and p-type reflection layers, tunneling junction layers, an oxidation layer, and metal layers for improved light output and efficiency at a given voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common cathode structure is used in VCSEL arrays, then the device complexity is reduced, but the lifespan of VCSELs is reduced due to inverse voltage application to unselected VCSELs
Solution Approach 1:
The patent segments the cathode connections by providing individual cathode electrodes for each VCSEL element rather than a common cathode connection. This segmentation allows independent control of each VCSEL, preventing inverse voltage from being applied to unselected elements, thereby resolving the contradiction between device complexity and VCSEL lifespan.
2Ease of manufacture
If a common cathode structure is used in VCSEL arrays, then the ease of manufacture is improved, but the operating voltage needs to be increased to compensate for parasitic inductance
Solution Approach 1:
The patent implements individual cathode electrodes for each VCSEL element, which segments the electrical connections and reduces parasitic inductance. This segmentation allows operation at lower voltages while maintaining manufacturing simplicity through integrated electrode design, thus resolving the contradiction between ease of manufacture and operating voltage requirements.
3Reliability
If individual driver FETs are connected to each VCSEL cathode, then the lifespan of VCSELs is improved by preventing inverse voltage, but the device complexity increases
Solution Approach 1:
The patent merges the cathode electrode function with the driver circuit function by integrating the electrode structure directly into the VCSEL device. This merging eliminates the need for separate external driver FET connections while still providing individual control capability, thus improving VCSEL lifespan without significantly increasing device complexity.
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 common anode structure enables greater light output at a given voltage, reduces unnecessary voltage application to unoperational VCSELs, and minimizes the impact of parasitic inductance, thereby enhancing the lifespan and operational efficiency of the VCSEL array.
Implementation Method 1
The VCSEL has a resonant structure in which the VCSEL has the direction perpendicular to the stack surface
Implementation Method 2
a lower tunneling junction layer disposed between the n type reflection part and the lowest layer, among the active layers, and configured to change a carrier type of a current
Implementation Method 3
an oxidation layer disposed between both the reflection parts and configured to improve oscillation efficiency by providing a photon confinement effect and an electron confinement effect
Data Source
AI summary
A VCSEL-based optical device having a common anode and a plurality of insulated cathode structures, and an optical module are disclosed. According to one aspect of the present embodiment, provided are: a VCSEL having a common anode structure so as to have higher optical output at a predetermined voltage; and a VCSEL array.