Segmented VCSEL Array Speckle Reduction
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Solution Overview
Problem
VCSELs and VCSEL arrays face limitations in achieving high optical power output due to current confinement issues and speckle noise, which affect their efficiency and application in illumination and sensing applications.
Innovation Solution
A segmented VCSEL array design with individually addressable segments and a diffractive optical element that allows for selective activation of segments to scale output power and control beam direction, reducing speckle contrast and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If VCSELs operate at high optical power output, then illumination intensity and sensing range are improved, but current confinement issues and speckle noise increase, reducing efficiency and performance
Solution Approach 1:
The VCSEL array is divided into multiple independently controllable segments or groups of emitters. By selectively activating specific segments rather than operating all emitters at full power, the patent reduces speckle contrast while maintaining high illumination intensity. This segmentation allows dynamic control of the emitting aperture to optimize between power output and speckle reduction.
Solution Approach 2:
The patent implements dynamic control of the VCSEL array by selectively activating different segments based on operational requirements. The emission characteristics, including aperture size and active emitter distribution, are dynamically adjusted to balance illumination intensity and speckle noise, rather than operating in a static high-power mode.
2Power
If VCSELs are operated at high power levels, then output power is improved, but current confinement issues arise, reducing power efficiency
Solution Approach 1:
The VCSEL array is segmented into multiple independently controllable groups. By activating only the necessary number of segments to achieve the required optical power output, the system avoids the current confinement issues that arise when all emitters operate at high power simultaneously, thereby maintaining higher power efficiency.
Solution Approach 2:
Instead of operating all VCSEL emitters at full power, the patent activates only the necessary portion (partial action) of the array to achieve the required optical output. This prevents current confinement issues and maintains better power efficiency by avoiding excessive current density in individual emitters.
3Power
If a single VCSEL emitter is used, then device simplicity is maintained, but maximum optical power output and efficiency are limited
Solution Approach 1:
The patent uses a segmented VCSEL array structure where multiple emitters are divided into controllable segments. This segmentation enables higher total optical power output while maintaining operational simplicity through selective activation of segments, effectively managing the trade-off between power capability and device complexity.
Solution Approach 2:
The VCSEL array is designed to perform multiple functions: it can operate in high-power mode by activating all segments, in efficiency-optimized mode by activating selective segments, and in speckle-reduced mode through dynamic segment control. This multi-functionality allows a single device structure to address various operational requirements.
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 segmented VCSEL array design enhances power scalability, maintains high efficiency across a broad range of output levels, and reduces speckle noise, offering improved performance for illumination and sensing applications.
Implementation Method 1
vertical-cavity surface-emitting lasers (VCSELs)... VCSELs and VCSEL arrays emitting in the range of 50 mW to 10 W of optical power
Implementation Method 2
a diffractive optical element that allows for selective activation of segments to scale output power and control beam direction, reducing speckle contrast
Data Source
AI summary
A segmented VCSEL array having a plurality of individually addressable segments, each segment comprising one or more VCSELs. In some cases, at least two of the plurality of individually addressable segments may be driven in combination. The plurality of individually addressable segments, in some embodiments, may be centered around the same central point. An optical element may be used in conjunction with the segmented VCSEL array, and in some cases may be aligned to the central point. The optical element may be configured such that light passing therethrough may be directed according to which of the plurality of individually addressable segments is activated. In some embodiments, the optical element is a grating or diffractive optical element. The grating or diffractive optical element could be patterned with optical segments that each correspond to at least one the plurality of individually addressable segments.